Sustainable cropping systems for dairy farms in the Northeastern US
At the Pennsylvania State University Agronomy Research Farm near University Park, PA, we continued operating our Sustainable Dairy Cropping Systems farm designed to produce all of the feed, forage, and tractor fuel needs for a typical 65-cow dairy farm on 240 acres. In the two diverse crop rotations, we continued monitoring the performance of innovative manure and weed management strategies designed to reduce nutrient loss and herbicide use, and compared two ways to integrate canola into a dairy crop rotation. The USDA ARS team completed the monolith lysimeter plots and began comparing total N losses among three manure management strategies. We met with the Advisory panel in April, hosted our first field day in June, and participated in a number of additional outreach and scientific reporting activities.
The Sustainable Cropping System farm focused on dairy production is based on ecological principles and processes, and tests the hypothesis that a farm can minimize off-farm inputs and rely primarily on natural processes to be both productive and profitable. The agroecological principles and goals are to: i) minimize nutrient and soil loss, and build soil organic matter and nutrient pools (via no-till, cover crops, manure injection, legumes) and promote biological processes for nutrient acquisition (legumes, soil biological activity, mycorrhizae), ii) enhance biological diversity and ecological interactions to optimize crop yields and minimize pest outbreaks (ex. crop rotation with diverse crop species and lifecycles, intercrops, and cover crops for weed suppression, disruption of insect movement, and promotion of beneficial insect populations), iii) be energetically efficient and productive (produce oilseed crops for farm fuels, use ecological principles to minimize the off-farm inputs of energy, nutrients, &amp;amp;amp;amp; pest control). The sustainable cropping systems were developed in the first 6 months of 2009 and were initiated at the Pennsylvania State University Agronomy Research Farm in March 2010.
Several strategies that meet the above agroecological system principles are evaluated, including: no-tillage, manure injection, crop rotations and intercrops of perennials, annuals, cover crops, and legumes, a roller-crimper, and a locally produced (New Holland) Straight Vegetable Oil (SVO)-powered tractor. To address two major challenges of no-till systems, we are comparing two innovative strategies to: i) conserve manure nutrients and ii) reduce herbicide use within two diverse crop rotations. We are evaluating the manure management strategies in the &amp;quot;forage rotation&amp;quot; and and weed management in the ‘grain rotation (Fig. 1)in a split-plot design. We are also evaluating green manure and mycorrhizae management in nested split-split plots. We are comparing red clover versus hairy vetch nested within the manure comparisons in the forage rotation, and canola vs canola and oats nested in the weed management rotation (see Fig. 1). The scientific comparisons will enable us to document system impacts of a broader range of options available to farmers. These comparisons will also enable the team to more fully understand the fundamental agroecological processes, to share our findings through scientific publications, and to contribute to advancing the science and adoption of sustainable agriculture.
Overall farm management (Tables 1-4) continued mostly as planned for our dairy cropping systems (Fig. 1). This year, however, unusually wet weather in spring (10.35 inches in April &amp;amp;amp;amp; May) and early fall (5.62 inches in August) made it difficult to conduct all field operations in a timely manner because delayed spring operations and planting delayed or prevented planting of fall crops. In particular, corn silage after red clover and hairy vetch was planted later than intended (FORAGE rotation; Fig. 1) and even with a short-season corn hybrid, winter canola could not be planted afterwards this fall 2011. Instead, in the forage rotation, we planted winter rye this fall and will plant spring canola in 2012. Further, the combination of very dry weather in mid-summer (0.93 inches of rain in July) resulted in below average yield of some crops.
We completed the construction of the field lysimeters in 2011, including the installation of surface and subsurface collectors, monitoring houses and sampling equipment (Fig. 2). Three manure application methods were tested for their performance within the forage rotation: conventional unincorporated manure application (broadcast); manure injection with a low disturbance applicator; and aeration of the soil followed by banding of manure over the aeration pits. Wet spring conditions and construction delays delayed manure application and silage corn planting until early June. The delayed planting followed by a mid-summer drought resulted in poor establishment of the corn. As a result, we decided to re-establish red clover on the field lysimeters and re-initiate the cropping systems trial in spring 2012. Despite this setback, we were able to derive a variety of observations related to nitrogen fate after manure application.
At every crop harvest in the NESARE Dairy Cropping Systems Trial, we collect three subsamples for forage or feed quality analysis from each of our main management treatments: i) manure management in the FORAGE rotation, where we are comparing injecting (IM) to broadcasting manure (BM), and ii) weed management in the GRAIN rotation, where we are comparing a suite of practices to reduce herbicide use (RH) with “standard” practices of herbicide use (SH) in a no-till cropping system.
In most cases, additional processing occurs to prepare a sample that is representative of what a farmer might submit for forage or feed quality analysis for a particular crop. We spent time refining our crop post-harvest processing in 2010 and 2011. For instance to simulate the fermenting that occurs in the ensiling process, subsamples of forage crops, including alfalfa, alfalfa, grass and companion crop mixtures, corn silage, and red clover, were vacuum sealed and stored at 30 degrees C for at least three weeks to simulate the fermentation that occurs in the ensiling process. The dairy scientist on our team, Virginia Ishler, noted that the forage quality analyses of our simulated silage samples were very similar to the forage quality ensiled at the Penn State Dairy Complex at University Park. For canola, we used an Oekotec single-dye press to extract oil from the grain, leaving a high protein meal that can be fed to dairy cows. This “cold” press extraction method can result in a canola meal that has a higher than desired fat content for the dairy ration. We found that drying the canola seed down to 5.5 to 7% moisture before pressing the seed was particularly important in order to maximally extract oil and produce a meal with the lowest amount of fat as possible with the mechanical Kern Kraft press (Fig. 3). For soybeans, we simulated roasting soybeans by putting raw soybeans in a muffle furnace at 146 degrees C for 30 minutes followed by cooling them in a funnel dryer for 30 minutes. This is the temperature and time period recommended for a commercial roaster by Hsu and Satters, J Dairy Sci., 1995, which we adapted to the laboratory setting. A comparison between three samples each of roasted and raw beans in 2011 revealed that roasting the beans in the laboratory dropped the % soluble protein from 73 % to 21 % (Fig. 4). According to Dairy One Lab’s Feed Composition Library, this is what is expected for roasted soybeans (http://www.dairyone.com/Forage/FeedComp/disclaimer.asp).
The virtual dairy operation was designed to represent a typical Pennsylvania tie-stall barn for the lactating herd and a bedded pack for young-stock and dry cows. Upright silos and Ag Bags are used to ensile forages. All corn grain, soybeans and canola meal are fed to the herd, as a total mixed ration. Rations for all the animal groups are formulated based on the 2001 NRC model and reflect very closely to what is fed at the Penn State dairy herd. Income over feed costs is monitored monthly for each scenario (BMSH or IMRH) to evaluate the impact of forage quality and quantity on profitability for the lactating cows. A cash flow plan is being developed for each scenario to evaluate the effect on purchased feed costs and how the cost of producing home raised feeds influences the breakeven income over feed costs/cow and breakeven net margin/cwt.
We organized a project Advisory Panel meeting that was attended by most of the faculty and graduate student researchers on April 6, 2011. The focus of the meeting was to update the advisory panel of recent project activities, treatment changes either already made or being considered, and of the field day scheduled for June 22, 2011. The advisory panel members’ comments were extremely appreciated as the team deliberated some of the management options for practical cropping practices in our study. We are currently planning our next meeting with the Advisory Panel in March 2012.
This NE SARE Agroecosystems project is one of three sustainable cropping systems research and outreach projects currently underway at Penn State. A half-day joint meeting of all faculty, graduate students, and post-doctoral researchers of the three projects was held on February 25, 2011. The goal of the event was to share project objectives, methods of investigation, and preliminary results to promote synergy among the teams. Posters were developed and graduate students and post-doctoral researchers gave brief presentations. Nearly thirty individuals attended. For more information, please see: http://extension.psu.edu/susag/news/2011/April-2011/2-triad.
Impacts and Contributions/Outcomes
Crop yields were collected for each crop entry point in the FORAGE rotation in 2010 and 2011; data was analyzed with a split-plot, mixed ANOVA model using PROC MIXED of SAS. Forage crop yields by cutting were analyzed with a repeated measures split-plot, mixed ANOVA model.
In both years, annual yields for the manure management comparison were not statistically different for any of the crop entry points (Table 5). For each forage cutting in 2011, the manure management comparison also was not significantly different for either the 1st or 2nd year alfalfa + orchardgrass stands (Table 6). This was not surprising for either crop entry point since neither receives manure. Also not surprising, the 1st year alfalfa and orchardgrass yielded half as much forage as the established 2nd year alfalfa and orchardgrass stands.
To compare the main management treatment effects on crop quality we compared a common set of forage and feed quality variables, including % crude protein (CP), % neutral detergent fiber (NDF), and net energy of lactation (NEL/Mcal/lb). We used a split plot model in a mixed ANOVA model in SAS to compare the quality of each crop entry in both rotations. For forage crops, we used the same model, but incorporated a repeated measures design for the multiple cuttings each year in the same plots. Thus, for forage crop entry points, we examined main management effects across cuttings and interaction effects between cutting month and main management.
We found no statistically significant differences between main management treatments for % CP, % NDF, or NEL (Mcal/lb) for all crops in the FORAGE rotation (Table 7).
Weed management was compared in wheat, red clover, hairy vetch, and the subsequent corn silage crop (FORAGE rotation) to compare the effectiveness of the two green manure cover crops on weed suppression. To quantify weed severity and treatment effects, weed density and biomass were collected throughout the growing season. Weeds in wheat were sampled both from the resident weed population and from subplots within the crop plots that were supplemented in fall 2010 with three weed species: i.(giant foxtail (Setaria faberi Herrm.), ii. smooth pigweed (Amaranthus hybridus L.), and iii. common ragweed (Ambrosia artemiisifolia L.), each at a rate of1500 seeds per. Weed density was measured by identifying and counting weeds in two randomly placed 0.7 m2 quadrats from the resident weed population and/or from supplemented weed subplots. Weed biomass was sampled by collecting aboveground weed biomass from the same areas, drying the samples at 37 degrees C for at least 48 hours, and weighing them.
Weed management in winter wheat did not differ between main management (broadcast or inject manure) treatments in the FORAGE rotation; however in split-split plots half of the wheat under each manure management treatment two green manures are compared. Red clover was drilled in one half of each manure treatment in April of 2011, and hairy vetch was planted in the other half approximately one month following wheat harvest. The plots underseeded to red clover were not sprayed with herbicide, while the hairy vetch plots were sprayed in early May with 0.6 fl oz/Acre Harmony Xtra (thifensulfuron-methyl + tribenuron-methyl). Weed biomass in wheat was sampled both before wheat harvest, and again after the wheat harvest and before hairy vetch planting. Weed density was also sampled after wheat harvest. While not statistically significant, there was a trend towards higher weed densities and greater weed biomass in the red clover plots, at all sampling points. There were no yield differences in the wheat plots interseeded with red clover or not (followed with hairy vetch), and weed biomass was not high enough to suggest that any reduction in yield could be attributable to competition from weeds. In the 2011 corn silage crop, there were no differences in weed density or biomass in corn following the 2010-planted red clover or hairy vetch.
Ammonia measurements were made on the field lysimeters immediately following application of manure on June 9 and 10, 2011. As most ammonia volatilizes in the first 1-3 days after application of manure, we were able to obtain a complete set of observations despite the early termination of the corn trials. Results point to significant conservation of ammonium-nitrogen with the use of alternatives, to broadcast applications. Injection reduced ammonia volatilization by 98% and aeration decreased loss by 44% as compared to broadcast application (Fig. 5). Specifically, injecting manure reduced peak ammonia emission rates compared to broadcast, while use of an aerator lowered relative losses.
Although surface runoff is a minor pathway for nitrogen loss, small differences in inorganic nitrogen concentrations were observed in runoff from the field lysimeters during the early growing season. Specifically, mean concentrations were lower with injection than with conventional broadcast application (Fig. 6). These findings follow previous research with phosphorus in surface runoff, and point to the beneficial effect of injection in removing nutrients from the zone of interaction between surface runoff and soil. Surprisingly, the highest concentrations of inorganic nitrogen were associated with aeration of the soil and banding of manure. Although our previous research points to high concentrations of nutrients in surface runoff with banding, broadcast application consistently yielded the highest concentrations. Notably, an absence of flow data from these initial events owing to late installation of flow-quantifying samplers precludes comparison of runoff loads (kg/ha). Later events in this growing season and next year’s trials will enable us to assess aeration can significantly lower surface runoff volumes, counteracting the effects of elevated concentrations.
Injection of manures in concentrated, below ground bands can lead to deletion of oxygen, making conditions more favorable for denitrification. Because the potent greenhouse gas nitrous oxide is a product of incomplete denitrification, its emission was monitored twice weekly following manure application. Our observations indicate that manure injection increased nitrous oxide emissions by 216% (1.9 kg nitrous oxide) during a 28 days period, compared to broadcast application, with the greatest rate of denitrification observed 10 days after manure application (Fig. 7). In addition to creating more favorable conditions for denitrification, reduced losses of ammonium-nitrogen with injection and subsequent nitrification appears to have created a larger pool of soil nitrate that was susceptible to denitrification.
Crop yields were collected for each crop entry point in the GRAIN rotation in 2010 and 2011; data was analyzed with a split-plot, mixed ANOVA model with PROC MIXED of SAS. Forage crop yields by cutting were analyzed with a repeated measures split-plot, mixed ANOVA model.
In 2010, the weed management comparisons, reduced herbicide (RH) and standard herbicide (SH), were significantly different across the crop entry points in the GRAIN rotation (p=0.008; Fig. 8 &amp;amp;amp;amp; Table 8). Further, a ‘weed management x crop’ interaction revealed that pure alfalfa in the SH treatment yielded higher than alfalfa with companion crops in the 1st and 3rd year forage crop entry points (1st year: p=0.001; 3rd year: p=0.001; Fig. 1 and Fig. 8). For the 1st year forage crop entry point, this is likely due to the fact that although alfalfa, pea, triticale, and orchardgrass in the RH treatment had a higher yield than the pure alfalfa in the SH treatment in the 1st cutting in May (p=0.013; Fig. 8), we decided not to harvest a third cutting in the RH treatment in fall. The pea and triticale companion crops had suppressed the alfalfa and orchardgrass to the extent that growth by the perennials was reduced that year. For the 3rd year forage crop entry point, we terminated the crop before a third cutting was taken in the fall to plant winter canola. It appears that the SH alfalfa alone treatment yielded better than the RH, alfalfa and orchardgrass, because the alfalfa produced more in mid-summer than the cool-season orchardgrass, and there were no fall harvests where orchardgrass could have contributed higher yields. Supporting this hypothesis is the fact that there were no significant differences between the RH and SH treatments in the 2nd year forage crop entry, which did include fall harvests.
In 2011, the weed management comparisons, reduced herbicide (RH) and standard herbicide (SH), were not significantly different across the crop entry points in the GRAIN rotation (Table 8). However, a ‘weed management x crop’ interaction revealed that the RH alfalfa and orchardgrass with triticale and in the 1st year crop entry point yielded more than the SH treatment (p=0.020; Table 8) while the reverse was true in the 3rd year forage crop entry (p=0.026; Table 8). The companion crops of pea and triticale, with the alfalfa and orchardgrass in the RH treatment yielded 7.5 times more than the pure alfalfa in the 1st cutting in May (p=0.001; Table 9), and although the reverse was true for the June cutting, pure alfalfa in the SH treatment yielded only twice as much as alfalfa + orchardgrass in the RH treatment (p=0.005; Table 9). We also chose to harvest a 3rd cutting in both RH and SH treatments in the fall, and there was no difference in yield between weed management treatments. For the 3rd year forage crop entry point, we terminated the crop before fall cuttings were taken to plant winter canola. Again, it appears that the alfalfa in the SH treatment yielded more due to the better growth of alfalfa as compared to orchardgrass in mid-summer. In August, the alfalfa + orchardgrass yielded ~50% less than pure alfalfa in the SH treatment. Again, there were no significant differences between RH and SH treatments in the 2nd year forage crop entry, which did include fall harvests.
For the majority of crop entry points, we found no significant differences between main management treatments for % CP, % NDF, or NEL (Mcal/lb) for all crops in the GRAIN rotation (Table 10). The exception in the GRAIN rotation is for the forage crop entry points. This is not surprising because in the ‘reduced herbicide’ management strategy in the GRAIN rotation, alfalfa, orchardgrass, pea, and triticale are planted in year 1, with pea and triticale permanently removed after the first cutting and leaving an alfalfa + orchardgrass mix as compared to pure alfalfa in the ‘standard’ herbicide management. In addition, differences in weed pressure (see weed management section), may contribute to differences we found in forage quality in the GRAIN rotation. For instance, in the forage, year 1 crop entry, % CP was significantly higher in the SH than in the RH rotation (p = 0.02), while significant interaction effects between main management and cutting month exist for % NDF (p = 0.0001) and NEL (p = 0.0003) (Table 10). In the forage, year 2 crop entry point, % CP was higher in the SH than in the RH rotation (p = 0.0247), % NDF was lower in the SH than in the RH rotation (p = 0.0196), and a significant interaction effect between main management and cutting month exists for NEL (p = 0.0708) (Table 10). Finally, in the forage, year 3 crop entry point, significant interaction effects exist between main management and cutting month for % CP (p = 0.0511), % NDF (p = 0.393), and NEL (p =0.0224). Aside from forage quality differences found in the GRAIN rotation, the forage and feed quality analyses indicate that the sustainable management practices (IM, RH) we use in our cropping rotations do not result in a reduction in crop quality compared to using more standard management practices (BM, SH).
The 2011 growing season marked the first comprehensive comparison of the weed management programs. The two treatments were compared primarily in the GRAIN rotation. The “Standard Herbicide” (SH) treatment utilized broadcast herbicide applications to manage weeds in corn grain, soybeans, and alfalfa. The “Reduced Herbicide” (RH) treatment combined banding herbicide, rolling a cover crop with a roller crimper to form a weed-suppressive mat, using a high-residue cultivator for weed control in corn and soybeans; and planting companion crops for weed suppression when establishing the alfalfa and orchardgrass In addition, in the reduced herbicide treatment alfalfa was terminated with a moldboard plow before planting canola, while glyphosate and 2,4-D were used to terminate alfalfa the standard herbicide treatment.
To quantify weed severity and treatment effects, weed density and biomass were collected throughout the growing season. Weeds in corn grain, soybeans, and canola were sampled as described for wheat in the ‘Weeds’ section in the FORAGE ROTATION. Weeds in forage crop entry points were quantified by: separating aboveground biomass into forages and weeds, weighing dry biomass, and calculating percent composition of each within the forage crop. Sampling occurred at the time of each cutting or alfalfa harvest. The SH alfalfa contained only alfalfa as a forage; RH alfalfa contained alfalfa, orchardgrass, triticale, and peas as forage species. Each species was dried and weighed separately. Weed species were separated into four categories by life cycle: annual broadleaf, annual grass, perennial broadleaf, and perennial grass. These were dried and weighed separately.
In corn grain and soybean in 2011, weed density and biomass were higher in the RH treatment as compared with the SH treatment. In the RH soybean in particular, soybeans were planted in 30 inch rows, but were drilled in 7.5 inch rows in the SH soybeans. Weeds that emerged in the RH soybean crop row were not controlled with the cultivation. However, both the post-emergence herbicide application in SH corn and soybean and the inter-row cultivation in RH corn and soybean reduced the number of weeds while yield did not differ between weed management treatments when analyzed with both crops as in the crop rotation comparison of main effects (Table 11).
When individual crop yields were analyzed, the SH soybean yield was about 10 bu/A more than the RH soybean in 2011 (Table 11). Although the drilled SH soybean initially established poorly in May 2011 (43,000 plants/A when desired population was 150,000 plants/A), the SH soybeans were replanted in early June with a no-till drill in 7.5 in rows, and when combined with post-emergence glyphosate, they quickly provided a closed canopy that was competitive with the weeds. The RH soybean were planted in 30 inch rows about 10 days after the SH soybean and used banded herbicide at planting and inter-row cultivation for post-emergence weed control. We can only speculate why RH yield was reduced, but delayed planting, the much wider row spacing and longer time to canopy closure, increased rye cover crop biomass, differences in soybean population and weed suppression may have contributed to reduced RH soybean yield relative to SH soybean. The drilled soybean in the CORN-SOY rotation yielded about 50 bu/A, which is similar to RH soybean (see ‘Yields’ section under ‘Across Rotations’ and Table 13). Planting date of these soybeans was more similar to that of the RH soybeans, further suggesting that yield was related to planting date as well as row spacing and population.
The establishment-year alfalfa in the GRAIN rotation was cut three times in 2011: in June, August, and October. Total forage yields for the year were 28% higher in the RH treatment. In particular, the June cutting of RH alfalfa had 7.5-fold more forage harvested than did SH alfalfa, likely due to the rapid growth of the annual triticale and pea in the RH alfalfa (Fig. 8). In August, the SH alfalfa yield was higher than the RH alfalfa; this is likely because the annuals suppressed the growth of the slower-growing alfalfa and orchardgrass in the RH treatment, as compared to the SH alfalfa alone. The proportion of weeds present in the forage was not different between treatments at any cutting, which differed from the 2010 results. The RH forage was significantly lower in average crude protein across all harvests, lower in Net Energy for Lactation in June and August, and significantly higher in % neutral detergent fiber at all cuttings. A detailed summary of the forage analysis can be found in the ‘Forage and Feed Quality’ sections.
The winter canola crop that was planted in fall of 2010 followed either alfalfa (SH), terminated with herbicide, or alfalfa and orchardgrass (RH), terminated by moldboard plow. There were no subsequent weed management tactics applied in canola; however, half of the canola in each of these treatments was planted with oats. Weed biomass was sampled immediately following canola harvest in 2011, and there was no difference in weed biomass between SH and RH canola crops. There also was no difference in weed biomass between canola alone and canola plus oats, under either main management. Because winter canola grows and develops a canopy before many important weeds in the spring, it successfully outcompeted the weeds.
We have a number of opportunities to make comparisons among our two diverse rotations (GRAIN and FORAGE rotations) and the one low-diversity rotation (C-S rotation) (Fig. 1). In 2010, there were no rotation history differences and no differences in canola yield between the rotations or the main management comparisons nested in the FORAGE or GRAIN rotation (Table 12). In 2011, however, canola in the GRAIN rotation yielded 26% more than in FORAGE rotation (Table 12). In the GRAIN rotation, canola was planted after alfalfa as opposed to after corn silage in the FORAGE rotation, and although 10 T/A more dairy manure was applied after the corn silage, it appears that more N was mineralized and taken up by the canola from the alfalfa N in the GRAIN rotation. This is supported by the observation that at flowering, canola plant tissue N levels in the grain rotation averaged 2.41% versus 2.15% in the Forage rotation. Sufficient N level for Canola at flowering have been reported as 2.4% by the Council of Canada. Chapt.9: Soil Fertility &amp;amp;amp;amp; Canola Nutrition. (http://www.canolacouncil.org/chapter9.aspx; accessed: June, 2011). Canola oil production (gallons/acre) in 2011 was also lower for canola in the FORAGE rotation compared with canola in the GRAIN Rotation (Fig. 9). In total, the FORAGE rotation canola produced 3140 gallons of oil while the GRAIN rotation canola produced 3775 gallons of oil. Further,in the FORAGE rotation due to the unusually wet spring and fall weather, corn silage harvest was delayed and we were not able to plant winter canola after the corn silage this fall 2011. Instead, we planted winter rye as a cover crop and will plant canola in spring 2012 in the FORAGE rotation.
Since canola yields were lower than we anticipated in 2010 and 2011 in both rotations, we sampled the seed lost during combine harvesting by collecting all seed lost from within two 1/8 meter2 quadrats in each canola plot. This intensive field sampling revealed that 35-40% of the crop was lost during harvest. Methods have been researched and will be employed to reduce combine harvest loss in 2012.
For corn grain yields in 2011, there were no significant differences between main management comparisons nested in the GRAIN or C-S rotation (Table 13). Interestingly, corn grain yields were significantly higher in the GRAIN rotation compared to the C-S rotation in 2011 (p=0.01; Table 13), as indicated by a ‘Crop*Rotation’ interaction effect when all corn and soy grain crop entries points were included in the nested split plot ANOVA model. This same comparison was not made in 2010 because the experiment had just begun and there was no legacy from main management strategies to compare. When the corn grain yields in the C-S rotation were compared on their own, no significant difference between manure management strategies was found in 2010, while yields in the inject manure (IM) strategy were higher than in the broadcast manure (BM) strategy in 2011 (p=0.031; Table 13).
For soy grain yields in 2011, there were no significant differences between main management comparisons nested in the GRAIN or C-S rotation (Table 13). This same comparison was not made in 2010 because the experiment had just begun and there was no legacy from main management strategies to compare. When the soy grain yields in the C-S rotation were compared on their own, there was no significant difference between manure management strategies in 2010 or 2011.
In 2011, we continued to assess the influence of crop management strategies on insects and slugs in the Sustainable Dairy Cropping Systems Trial. Because all of the treatments (e.g. cover crops, prior crops, etc.) were fully in place this year, we were able to measure the impact of the complete cropping systems on populations of pest and beneficial invertebrates. As in 2010, we implemented scouting protocols to guide IPM decision-making for key pests including soybean aphids in soybean, potato leafhopper in alfalfa, and early-season pests and European corn borer in corn. To continue building knowledge about slug biology and management, we again monitored over 160 shelter traps in corn, alfalfa, and canola over the growing season. Finally, we measured the influence of management practices on beneficial invertebrates in two ways: 1) using 160 pitfall traps in corn and alfalfa plots, and 2) using sentinel caterpillars to measure the ecosystem service of predation.
Our efforts to implement IPM in the experiment provided an opportunity to assess the impact of our cropping strategies on pest incidence and severity. In soybeans, we expected 2011 to be an outbreak year for soybean aphid based on previous patterns of pest occurrence. However, for still obscure reasons, this threat did not materialize in the region; soybean aphids never exceeded 30 aphids/plant in any treatment, a level substantially below the economic threshold (250 aphids/plant). At these low levels, it is perhaps not surprising that we saw no differences in soybean aphid pressure between rotations or weed management strategies. In alfalfa, potato leafhoppers continued to be a challenging pest. In the grain rotation, newly established alfalfa-grass stands with a nurse crop hosted lower potato leafhopper densities than alfalfa-only stands (Fig. 10a). A similar, but weaker effect was also seen in the second-year stands (Fig. 10c). Alfalfa-grass plots in the forage rotation generally experienced similar or reduced leafhopper pressure compared to the alfalfa-grass treatment in the grain rotation (Fig. 10bd). Despite these differences, all plots exceeded the economic threshold for potato leafhopper with similar frequency. In corn, the most significant early-season insect pest damage was inflicted by black cutworm caterpillars, which cut corn seedlings at soil level. Cutworm damage at growth stage V5 was higher in the grain rotation (where corn follows rye) than in the forage or corn-soy rotations (where corn follows a legume cover crop or no cover) (Fig. 11). However, even the highest cutworm damage we found was still well below the economic threshold of 7% cut plants. European corn borer damage was low in 2011 compared with 2010. As expected, corn borer damage was greater in the non-Bt corn in the forage and grain rotations than in the transgenic Bt corn in the corn-soy rotation (Fig. 12). However, in all cases corn borer damage was low (average of less than 1 tunnel per plant) and would not be expected to reduce yield. In canola, scouting in 2011 failed to discover significant insect pressure. This was in contrast to 2010 when the spring-planted canola was challenged by flea beetles and lygus bugs. Choosing fall rather than spring canola may be a strategy to avoid insect damage on canola in the Northeast.
We continued to build knowledge about slug biology and management this year. Despite the wet weather, slug populations were surprisingly low in the spring of 2011. As a result, slugs caused relatively little damage to spring-seeded alfalfa stands and corn seedlings. Nonetheless, over the season slug activity increased and showed some interesting responses to crop management practices. The gray garden slug (Deroceras reticulatum) was again the dominant slug species at our site, especially during times of crop establishment in spring and fall (Fig. 13). In alfalfa, slug activity-density was similar in alfalfa-only stands and alfalfa-grass stands with a nurse crop. In corn, slug activity-density appeared slightly higher in spring in the forage rotation (preceded by a legume cover crop) than in the grain or corn-soy rotations (Fig. 14). This was likely related to the significant amount of surface residue in the forage rotation, and was associated with slightly increased slug damage to corn seedlings (Fig. 15). However, as the season progressed, the pattern of slug activity-density changed. In the late summer and fall, slug activity-density was higher in the corn-soy rotation than in the forage or grain rotations (Fig. 14). This was especially surprising given that the corn-soy rotation did not have a prior cover crop, and so was generally lacking in residue. We are not certain what caused slug activity to become so high in the corn-soy rotation, but one possibility is that decreased natural enemy activity (see below) played a role. Within the grain rotation, fall slug activity was higher in the standard herbicide treatment than the reduced herbicide treatment (Fig. 16). This is probably a result of the inter-row cultivation used in the reduced herbicide treatment. Thus, diversifying weed control strategies may have the side benefit of suppressing slug populations. Since slugs mate and lay eggs in fall, the decrease in slug activity-density in the reduced herbicide treatment may translate into fewer slugs in spring. As the experiment continues, we will see how changes in slug populations accrue across seasons. Fall crop establishment was challenging in the wet, cool weather of 2011, and slugs most certainly contributed to this challenge. Four weeks after planting, in spite of high variation in plant densities across blocks, winter canola planted after alfalfa that plowed had 75% more plants than winter canola planted after alfalfa terminated with herbicide and no tillage, suggesting that using tillage to avoid another herbicide application may also provide some slug control (Fig. 17a). Damage ratings of canola plants that were present at that time did not different between the treatments (Fig. 17b), although two months after planting in November of 2011, some blocks, had essentially no canola. Fall planted alfalfa and orchardgrass (FORAGE rotation) will very likely need to be replanted in spring 2012.
In addition to our efforts to measure pest populations, we tested the influence of our treatments on natural enemies and the predation services they provide. In 2011, we collected pitfall trap samples in corn and alfalfa plots on seven occasions spread over the season. We are in the process of sorting and identifying these samples, and expect them to provide valuable information on treatment effects on natural enemies. In addition, we measured predation on sentinel waxworm caterpillars in corn plots in all three rotations, once in mid-June and again in mid-July. Each plot received 32 pinned caterpillars, half under exclusion cages (allowing access by arthropods only) and half open to vertebrates (e.g., mice, birds) as well as arthropods. In June, predation in the caged treatment was extremely low both day and night (Fig. 18). Arthropod activity may have been low due to unseasonably cool temperatures around the sample date. In the uncaged treatment, predation was higher, and observations suggest that birds (e.g. robins) were mainly responsible. In July, predation in the caged and uncaged treatments were similar both day and night, suggesting that arthropods were responsible for a larger share of caterpillar predation. During the night sample, arthropod predation was greater in the forage and grain rotations than in the corn-soy rotation (Fig. 19). Dominant arthropod predators included ground beetles (esp. Pterostichus melanarius), ants, wolf spiders and harvestmen. The reduced predation in the corn-soy rotation may have been a lingering influence of a typical at-planting insecticide treatment that was not used in the other rotations, and/or it may have been related to the lack of residue in the corn-soy rotation, providing poor habitat for natural enemies.
Our results thus far support the hypothesis that diverse crop rotations using conservation practices and IPM can reduce insecticide use while preventing economic damage to crops. In the forage and grain rotations, the only crop to receive an insecticide spray in 2011 was alfalfa, for potato leafhoppers. To reduce the number of sprays for this pest, we used regular scouting and early cutting whenever possible to manage leafhopper populations. As a result we were able to spray only once over the season and maintain forage quality (see ‘Forage and Feed Quality sections), contrary to the practice of some farmers who spray shortly after each cutting. In corn, we compared our diverse rotations with a simple corn-soy rotation reliant on pre-emptive pest management practices. In the corn-soy rotation, the use of transgenic Bt corn and an at-planting pyrethroid insecticide did not result in tangible pest control benefits relative to the forage and grain rotations. In fact, at-planting insecticides may have been counter-productive, if they contributed to low predation services by arthropods in July, and high slug populations in the fall. Continued data collection in this system will allow us to test this concept further. Slugs continue to be the least manageable pest in our system, particularly in fall crops. We hope to use what we have learned so far to further modify these systems to avoid slug problems. For instance, planting canola earlier in late summer, may allow plants to become established before slug pressure is heavy.
We assessed the impact of cropping rotation and management on arbuscular mycorrhizal fungi in corn, canola, and legume crop entry points within the NE SARE Sustainable Dairy Cropping Systems Trial.
First, in 2010, to determine if the genetically modified corn used in the experiment had an impact on mycorrhizal colonization we compared sister varieties of conventional and genetically modified corn. The genetically modified corn was pioneer variety 35F48AM with HXX, LL, and RR2 traits. The conventional and genetically modified corn varieties were planted in paired locations and were harvested approximately 10 days after germination to assess colonization. Colonization rates were compared using a paired t-test. There was no difference in the colonization of the two varieties by arbuscular mycorrhizal fungi (p = 0.25).
Next, in the summer of 2010, we attempted to assess the impact of increasing the number of mycorrhizal crops planted on arbuscular mycorrhizal colonization. Specifically, we attempted to compare the inoculum potential of arbuscular mycorrhizal fungi in plots with alfalfa (1 mycorrhizal crop) to plots with alfalfa, orchardgrass, triticale, and pea (4 mycorrhizal crops) and plots with alfalfa (1 mycorrhizal crop) to plots with alfalfa and orchardgrass (2 mycorrhizal crops). To assess inoculum potential, corn bioassay plants were planted from seed in all plots. The trap plants were harvested approximately two weeks after germination and assessed for colonization. Colonization data was analyzed using a split plot ANOVA with rotation and block as factors. There were no differences between plots with 1 mycorrhizal crop and plots with 4 mycorrhizal crops (Fig. 20, p=0.82) and plots with 1 mycorrhizal crop and 2 mycorrhizal crops (Fig. 21, p=0.72). However, colonization of all bioassay plants was high indicating that samples were taken too late to assess early colonization. Differences in early colonization of plants by arbuscular mycorrhizal fungi may be important for overall yield so we attempted to repeat this experiment in 2011. Unfortunately, due to the drought in June, the corn bioassay plants used to assess colonization in these plots did not survive and subsequent attempts to replant were unsuccessful. We will attempt to repeat this experiment in 2012.
In the summer of 2011, all corn entry points in the grain, forage, and corn-soy rotations were sampled to determine if there was an overall impact of rotation and management on mycorrhizal colonization. In all plots, corn seedlings were harvested at the third leaf stage and assessed for arbuscular mycorrhizal colonization. Colonization data was analyzed using a split plot ANOVA with rotation and block as factors. Colonization of corn plants in the corn-soy rotation and the grain rotation were reduced compared to the two corn silage plots (following alfalfa in one case and red clover or hairy vetch in the other) in the forage rotation (Fig. 22, p=0.01). The reduction in colonization observed in the corn-soy rotation and the grain rotation plots is likely the result of field management the prior winter. The plots in the corn-soy rotation were left fallow and the plots in the grain rotation had a rye cover crop over the winter. Rye does not form strong mycorrhizal associations, so in both of these scenarios the mycorrhizal fungal populations may not have been supported over the fall and winter. Conversely, in the forage rotation, corn silage plots had legumes present in fall and winter and some since the prior spring. One crop entry had alfalfa and orchardgrass growing the prior year, fall and winter; the other had either red clover present since the prior spring or hairy vetch present since fall. Each of these legumes form mycorrhizal associations and likely supported the fungal populations over the winter resulting in the higher levels of trap plant colonization that we observed.
Finally, we assessed the impact of intercropping canola with oats on mycorrhizal fungal colonization of subsequent crops. Canola is a non-mycorrhizal crop and has been shown to reduce arbuscular mycorrhizal fungal populations and their ability to form associations with subsequently planted crops. Oats, a mycorrhizal species, were intercropped with canola in an attempt to support mycorrhizal fungal populations. We compared the extent of arbuscular mycorrhizal colonization of 10-day old corn bioassay plants grown after canola to those grown after canola and oats. We saw no difference in the colonization of the corn bioassay plants in the canola and the canola plus oats plots (Fig. 23, p = 0.07). However, there was a reduction in the colonization of the corn bioassay plants in the reduced herbicide treatment compared to the standard herbicide treatment in the canola plots (Fig. 23, p = 0.04). The reduced herbicide treatment was tilled with a moldboard plow and this soil disturbance probably accounts for the observed reduction in colonization. The standard herbicide treatment was not tilled.
The outreach highlight of the year was the June 22, 2011 field day when we shared the project with farmers, farmer advisors, government agency personnel, non-governmental organizations, and researchers from other institutions. The event drew an attendance of 105 and included field plot tours/discussions, indoor presentations of selected components of the project, a buffet lunch, and a farmer panel discussion that centered on many components being tested in this research. For more information, see: http://extension.psu.edu/susag/news/2011/April-2011/2-triad.
For the field day, of the 105 in attendance, 86 were individuals who were not directly associated with the project. Of this number, forty-five attendees or 52% responded to all parts of an evaluation (see evaluation summary; Fig. 24). In brief, of those responders, 15.5% were agriculture producers who collectively managed 1667 acres. Ninety eight percent of N=45, felt the information received was of good to excellent value. Ninety-three percent of those responding to the farmer panel discussion indicated that this activity was of good-to-excellent value to them. Throughout the day, both in the workshops and during the tour, presenters emphasized sustainable agriculture concepts, to increase attendees’ knowledge. Our evaluation suggested that for many of the concepts, we succeeded (Fig. 24).
An outcome of our 1st annual Triad symposium (see ‘Part3: Accomplishments and Milestones’) is that the three sustainable cropping systems group at Penn State University plan to regularly hold events and meetings together. For example, some members of the above three project teams came together again, along with the Penn State Sustainable Agriculture Working Group, Pennsylvania Certified Organic (PCO), and other sustainable research and education groups from Penn State, for a field plot tour and discussion on June 10, 2011. Approximately twenty-five were in attendance as the group traveled between research project sites for discussions of research objectives, plot layout, plot maintenance, and research methods. All in attendance agreed that the cross-dissemination afforded by the above two events helped all understand more about sustainable system research being conducted by colleagues, and that this will help to improve the quality of work being conducted. Additionally, On Oct. 1, Heather Karsten shared our experiment with Penn State’s Undergraduate Sustainable Agriculture Club and team members from the other two sustainable cropping systems projects did the same. In 2012, members of the NESARE Dairy Cropping Systems and ROSE (Reduced tillage Organic Systems Experiment) projects plan to co-host a field day together.
Conservation practices in our project are being demonstrated on farms through our Natural Resource Conservation Service (NRCS) Conservation Innovation Grant that was funded in summer of 2009. Practices that farmers were most interested to try include: shallow-disk manure injection in a no-till cropping system and the use of the cover-crop roller to manage tall cover crops and create high residue mulch. This CIG NRCS project is described on a webpage linked to our NESARE Sustainable Dairy Cropping Systems project website. The website also provides information about the eight cooperating demonstration farms, four cooperating commercial manure haulers and county extension educators on a series of webpages (See: http://extension.psu.edu/cropping-systems/about). With the NRCS CIG funds we created internet links to an alphabetically ordered list of extension publications on the sustainable agriculture practices employed in our cropping systems and relevant information. We also created a webpage with links to short videos of the cooperating farms employing shallow-disk manure injection and the cover crop roller-crimper. The videos were created by the cooperative extension educators with funds from a 2010 CIG NRCS grant that demonstrates cover crop mixtures on 10 farms in PA as well as manure injection, and involves working with farmer networks to promote adoption of conservation practices. Our 2009 CIG NRCS project is referenced in a magazine article on “Manure Incorporation in No-Till Systems”. The summary can be found in the May/June 2011 edition of Crops and Soils, an American Society of Agronomy publication.
Approximately ten faculty, staff, and students traveled to the farm of one of our project’s farmer advisors, Byron Hawthorne on July 18, 2011. While there, they viewed and discussed the cover cropping and crop rotation practices that Byron and his son employ on their dairy farm, as well what information they use and how they decide to try new practices.
One hour tours and brief discussions of our Sustainable Dairy Cropping Systems project were hosted each day during Penn State’s annual Ag Progress Days event on August 16 – 18, 2011. The insect and slug management team used data from this project in 12 extension presentations on slugs and slug management. These presentations were attended by 1,083 growers and associated agricultural professionals. Approximately 75 individuals attended the tours. In addition, on September 29, 2011, Heather Karsten presented an interactive tour and sustainable agriculture quiz as part of a PSU Agroecology high school student recruitment weekend. High school students and their agricultural science teachers from four high schools across Pennsylvania participated, for a total of 25 participants. On October 10, Maggie Douglas, Heather Karsten, and Glenna Malcolm took high school students, in the Plant Sciences Academy, to see how canola seed is pressed for oil and out to our field site to explore the challenges we have growing canola in a no-till system with slug pressure.
Our project team continues to make use of our website. It can be found at: http://cropsoil.psu.edu/research/cropping-systems. As of November 28, 2011, there had been 2600 hits on our website. The website describes the project, the treatments being investigated at our research site, brief biographies of personnel involved, and outreach activities that are being planned (see below), links to the NRCS CIG project, and a list of useful documents and videos including a new handout, called ‘Canola Fueled Tractors’, that was created collaboratively by Doug Shauffler, the researcher and manager of the oil seed pressing at Penn State University, Andrew Kirk, an undergraduate student who worked on our project this summer, and Heather Karsten who mentored Andrew Kirk. Andrew Kirk also created a video in summer 2011 detailing the process of pressing canola seed for oil to run a straight vegetable oil powered tractor, which will be to the website soon when it has been completed with closed captioning.
- Research posters were presented at the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of American Annual Meeting in October 2011 in San Antonio, TX. Poster titles were as follows: i. Heather Karsten, Glenna Malcolm, Douglas Beegle, William Curran, Curtis Dell, Peter Kleinman, Thomas Richard, Virginia Ishler, John Tooker, Ronald Hoover, and Roger Koide: Integrating winter canola into dairy crop rotations ii. Emily Duncan, Peter Kleinman, Curtis Dell, Doug Beegle, and Heather Karsten: Improving manure management efficiency and environmental trade-offs iii. Glenna Malcolm, Heather Karsten, Douglas Beegle, William Curran, Curtis Dell, Peter Kleinman, Roger Koide, Ronald Hoover, Thomas Richard, John Tooker, and Virginia Ishler: Sustainable dairy cropping systems to produce forage, feed, and fuel Insects and Slugs Team: Review of slug biology and management to be available open-source for researchers, farmers, and agricultural professionals: Douglas, M. and J. Tooker. Slug (Mollusca: Agriolimacidae, Arionidae) ecology and management in no-till field crops, with an emphasis on the mid-Atlantic region. (Journal of Integrated Pest Management, accepted w/ minor revisions). Presentations: Karsten. H. D. 2011. Investigating Strategies for Sustainable Cropping Systems. Horticulture Dept. Penn State University Spring Seminar Series. March 30, 2011 Malcolm, G.M. and Karsten, H.D. 2011. Sustainable dairy cropping systems to produce forage, feed, and fuel. Post-doctoral Research Exposition, April 12, 2011. Penn State University. Tooker, J. and M. Douglas. 2011. Research update on slugs in Pennsylvania. Presented to the Northeastern IPM Center’s High Residue Cropping Systems IPM Working Group, August 2011, Newark, DE.
- Tables 8- 10: Grain Rotation Yields and Forage Harvest Yields
- Across Rotation Yields
- Figure 8: Grain Rotation
- Figures 18 & 19: Predation figures
- Across Rotations:
- Lysimeter N:
- Forage Rotation Yields, Quality, & Weeds
- Figures 10-12: Insects
- Figures 13-17: Slug figures
Soil Scientist and Adjunct Professor
USDA-ARS-Pasture Systems and Watershed Management
Building 3702, Curtin Road
University Park, PA 16802
Office Phone: 8148653184
Penn State Cooperative Extension
310 Allen Rd. University Park
Carlisle, PA 17013
Office Phone: 7172406500
The Rodale Institute
611 Siegfriedale Road
Kutztown, PA 19530
Office Phone: 6106831491
Soil Scientist and Adjunct Associate Professor
USDA-ARS-Pasture Systems Watershed Management Rese
Building 3702, Curtin Road
University Park, PA 16802
Office Phone: 8148630984
Penn State Cooperative Extension
310 Allen Rd. University Park
Carlisle, PA 17013
Office Phone: 7172406500
Nutrient Management Specialist
Dept. of Dairy and Animal Science
343 Agricultural Sciences and Industries Building
University Park, PA 16802
Office Phone: 8148633912
Sustainable Agricultural Systems Lab USDA ARS
Bldg 001, Rm 117, BARC-West
10300 Baltimore Avenue
Beltsville, MD 20705
Office Phone: 3015045324