This experiment evaluates the yield and forage quality of twenty winter wheat (Triticum aestivumL.)based double cropping systems and five single cropping systems in Indiana. It is our hypothesis that winter wheat based cropping systems yield competitively to single cropping systems on a dry matter and grain basis, while providing winter cover for soil and producing high quality forage earlier in the season than traditional silage crops. Winter wheat exploits late fall and early spring opportunities for crop growth during a time-period when, traditionally, little other crop growth occurs in Indiana. Winter-wheat based crop programs also better distribute farm machinery and labor requirement across the year. Of the eleven11 forage and nine grain production systems, five were single-crop systems. Winter wheat exploits late fall and early spring for crop growth in which little else is productive in Indiana and better distributes farm machinery and labor requirement across the year.
Two winter wheat varieties and one triticale (X. Triticosecale Wittmack) were sown in late September at the Agronomy Center for Research and Education near West Lafayette, IN. in the fall of 2008 and 2009. Small grains were harvested at boot stage (middle May) and heading (early June) as whole plant green chop and silage, respectively and then in early July for grain and straw. Moisture content and yield were recorded from each small grain at each harvest. One of the winter wheat varieties was sown on the plots which were used for double crop systems. Immediately or soon after each wheat/triticale harvest date, second crops of corn or soybean or sorghum intended for either grain or silage production were planted in the wheat stubble or in bare ground control plots.
The forage quality of the three wheat harvests and all silage second crops were evaluated by ANKOM fiber analysis, Kjeltec crude protein, aerobic stability by temperature change and In vitro dry matter digestibility. Digestible dry matter (DDM) yield of small grains was maximized at the second wheat harvest (5.2 Mg ha-1 and 6.14 Mg ha-1 in 2009 and 2010, respectively). There were no significant differences between wheat and triticale DDM at the first two planting dates, however, triticale yielded more numerically than winter wheat. Of the second crops planted following the first wheat harvest, single crop silage corn yielded the most DDM (14.9 in 2009 and 14.0 in 2010 Mg ha-1). In 2010, single crop silage corn was similar to single crop silage sorghum. There was a significant yield loss associated with planting into wheat stubble: 22.8 and 25.7 % yield reduction for silage corn in both years and 27.7 and 23.6% for silage sorghum. At the second harvest date, there were no significant differences among corn, sorghum or sweet sorghum treatments in DDM. At the second date, all forage species were planted into wheat stubble. At the third planting, silage sorghum yielded more DDM than sweet sorghum, 6.5 MG ha-1 compared to 5.2 Mg ha-1, however this was not found in year two. In general, year two was more productive for silage crops.
Grain production for corn was negatively affected by both delayed planting (reduction of 11%) and planting into wheat stubble (reduction of 21%). Delay in planting to the third date affected soybean (43.2 % yield reduction), though wheat stubble did not affect grain yield at the first and second planting date. No change was observed in grain sorghum sown into wheat stubble or bare ground at the second planting date.
Agriculture in Indiana is dominated by corn and soybean production, which account for 38.4 and 35.1%, respectively of 5.99 million hectares in production (NASS, 2010). Diversifying production by incorporating winter wheat based cropping systems will address demand for animal feed while reaping the environmental benefits of no-till production. Winter wheat production utilizes radiation later in the fall and earlier in the spring (Beleyea et al., 1978), distributes labor and equipment use across more of the year, and provides environmental services of a winter cover crop. Silage production is a complex undertaking, involving specialized equipment, labor, and input costs which are not incurred in grain production and must be considered on a profitability basis prior to adoption (Rotz et al., 2003).
Forage species are evaluated by yield and fiber content. Year-to-year environmental variation has been identified as the major factor affecting total forage yield in wheat (Walker et al., 1990), forage corn (Zea mays) (Fairey, 1980; Wiersma et al., 1993) and sorghum (Sorghum bicolor) (Venuto and Kindiger, 2008). High levels of fiber have been linked to low digestibility, (Lewis et al., 2004) and lower animal weight gain (Brosh et al., 1989). Stage of maturity is a principle factor in forage quality (Walker et al., 1990; Black et al., 1980) due to the accumulation of lignin as plants mature (Barnes and Marten, 2012), though total yield increases across the season (Darby and Lauer, 2002). Therefore wheat harvested earlier in the season, though accumulating less dry matter, is highly digestible.
There have been yield losses observed when silage and grain corn crops are planted into standing wheat stubble (Opuku et al., 1997; Leep, 2002) and when planting is delayed (Fairey, 1980; Lewis et al., 2004; Lauer et al., 1999). However, straw mulch and wheat stubble preserve soil moisture (Opuku and Vyn, 1997, Wicks et al., 1997; Unger, 1984) which may be advantageous to second crops in a dry year. This effect is reduced or unseen in soybean (Hershman and Bachi, 1995; Caviglia et al., 2011). In dry areas, grain sorghum yield improves when planted into wheat stubble from the previous growing season (Unger, 1984).
Winter wheat based systems have the potential to be highly productive in Indiana. Grain and silage yields are depressed by the presence of wheat stubble, but on farms which support cattle, double-crop systems may be competitive with conventional single crop grain production systems.
We accomplished our objectives/performance targets by successfully completing the experiment and collecting relevant data to explore this topic. Results have been presented at the American Forage and Grasslands Council Annual meeting, Agronomy Society meetings, Purdue University small grains field day and Hay Day, public defense at Purdue University, and published in the dissertation of Samantha Shoaf.
This experiment was completed at the Agronomy Center for Research and Education (ACRE) near West Lafayette, Indiana over two growing seasons from the fall of 2008 to the fall of 2010. Plots 10 m long and 5 m wide were in randomized complete blocks with four replications. The center 1.5 m of each plot was harvested in all treatments. There were twenty systems assessed: fifteen double-crop treatments and five single-crop control treatments. Winter wheat line INW0412 was planted in all double crop treatment plots. The biomass or grain yield of INW0412 was not measured from the treatment plots; instead, it was recorded from the small grains plots described below. Inclusion of the single crops allows measurement of the effect of wheat stubble on production.
Three small grains crops, two winter wheats (INW0412 and Kaskaskia) and one 8X triticale (NTO4432) were planted in randomized complete block with four replications in the center of the experiment. Each plot was seeded 10 m long and 6 m wide. Rows were spaced 15 cm apart, and 30 cm between plots. The small grains were planted at a seeding rate of 3.77 million seeds ha-1. Each plot was split to three harvest areas 1.5 m wide strips the length of the plot. The area which was harvested at each date was randomized. The small grains were harvested at boot (19 May 2009 and 26 May 2010), heading (9 June 2009 and 7 June 2010) and grain maturity (29 June 2009 and 1 July 2010). In 2009, the triticale was not ready for grain harvest until 6 July. The biomass harvested at boot was dried to constant weight at 60? C and analyzed for feed quality, in practice, this high moisture product would be fresh-fed as ‘greenchop’. The biomass harvested at heading was ensiled. At grain maturity the grain was harvested using a Wintersteiger Nursery Master Elite (Wintersteiger, Reid, Austria) plot combine and collected in burlap bags. The grain was dried at 35? C for two days and test weighed. After harvest, the straw was collected by raking into burlap bags and stored in a dry barn until weighed and sampled. Dry matter was determined by drying to a constant weight at 60? C.
Every effort was made to plant the second crops on the same day that the small grains were harvested. There were some situations in which this was impossible due to weather or equipment limitations. Between wheat harvest and germination of the double-crop, all plots were treated with Roundup to limit competition associated with wheat plant regrowth. Any wheat which did initiate regrowth in a treatment plot was hand sickled to reduce competition between wheat and the second crop. All treatments planted at the first planting date were seeded into both bare ground and 8 cm wheat stubble.
Agronomic production practices for each crop were best management practices as recommended by Purdue University. The grain sorghum and soybean crops were harvested mechanically from the center 1.5m of the plot with combines which measured the moisture content of the grain during harvest. Grain corn was harvested by hand from the center two of six rows (1.5 m) and mechanically shelled and dried to a constant weight at 60? C to determine moisture content.
Each silage crop was ensiled in mini-silos of approximately 5-7 kg and stored for at least 60 days prior to analysis. Upon opening the silos, three gallon-sized plastic food storage bags were filled: one for aerobic stability analysis, one for DM analysis (which was ground and used for fiber and digestibility analysis once dried), and one to be kept in the freezer as a contingency plan. Two quart-sized food storage bags were filled for duplicate VFA analysis. The aerobic stability and DM analyses were completed immediately, while the VFA and freezer samples were stored at -20º C until analysis. Silage samples were analyzed for pH, fiber fractions, crude protein, volatile fatty acid content, aerobic stability, and in vitro dry matter digestibility according to established ANKOM and Kjeldahl protocols.
This experiment demonstrates a variety of factors which influence forage yield and quality parameters. The two seasons included in this study were very different, with 2010 having significantly more precipitation in the spring, which delayed the second planting date by two weeks. This is an inherent risk of this type of system. Soil compaction from using production-scale equipment on soils which was still wet made stands in the second crops more erratic in 2010. Also, the residue from wheat on the soil surface retains moisture longer than bare soil. Likewise, in the fall, early frost limits the capacity to achieve field dry-down and a wilting procedure may be more practical on farm scale to ensure timely harvest. In 2009 the sweet sorghum from the third planting date was harvested at 22-23% DM content, which is too wet to reliably ensile. Dry matter content was monitored using single plant samples taken regularly in the fall and plants were harvested at or near 35% dry matter, earlier harvest and subsequent wilting may have improved total dry matter yield.
Winter small grain forage yield was affected by harvest date, with the highest yield at heading stage. Triticale in all instances yielded numerically more biomass than the two winter wheat lines, with the exception of the first planting date. Yearly variation affected the total amount of small grain biomass at each harvest. Triticale was less digestible than either winter wheat variety at the first two harvest dates, due to larger lignin fraction in the plant. At the third planting date, the lignin fraction was reduced relative to the first two dates. Fiber data observed in this study are likely valid for a large area representative of Indiana. Belyea et al. (1978) found in a study of four locations of a single winter wheat variety in Northwest Missouri that there were no significant differences in fiber content, protein or in vitro digestibility, implying that these are genetically controlled traits and in a similar season, nutritional value of a winter wheat variety may not vary spatially.
Second crop biomass yields were decreased by the presence of wheat stubble compared to sowing into bare ground plots. Planting into tall wheat stover at the third planting date had no effect on DM yield compared to the shorter wheat stubble. Crude protein was higher in forage and sweet sorghum tall wheat stubble treatments. Relative fiber content of winter wheat and silage corn in this study are similar to previously published results. Winter wheat ensiled at boot stage contains more ADF (significance not indicated by the authors) than corn similarly ensiled at dent stage in two separate trials reported by Baxter et al. (1980). However, there are a wide variety of reported values for fiber fractions in each species, which vary as a function of species, environment (Nelson and Moser, 1994), and maturity at harvest (Walker et al. 1990; Black et al., 1980; Cherney and Marten, 1982b).
Winter small grains crops harvested at heading produced the most digestible biomass. This, combined with the minimal reduction in digestible DM production of the same species from the first to the second planting dates when planted in wheat stubble, indicates that this is the best harvest option for dual forage production systems.
At the first planting date, the most digestible silage second crop was silage corn. However, adjusting the DM yield to reflect digestibility, both the silage corn and sorghum are equally high producing. It is interesting to note that planting into wheat stubble significantly reduced digestible DM yield in 2010.
At the second planting date, there were no differences between silage corn, silage sorghum and sweet sorghum on a DDM production basis. In this case, the crop which is most suited for production at the given location should be selected.
Silage sorghum, whether planted into tall or short wheat stubble was numerically (and statistically in 2009) the highest digestible DM producing crop at the third planting date. A limitation of this study is that we did not record the change in straw yield with the different stubble heights, and this may give the short straw system a productive advantage. The straw yield reported in this study is from short (7 cm) harvests in each of the three small grain varieties.
Corn grain was detrimentally affected by planting into wheat stover and delaying planting, this has been previously reported by Opoku and Vyn (1997) and Lauer et al. (1999). Soybean was unaffected by wheat straw, but grain yield was decreased by delaying planting to the third date. Hershman and Bachi, (1995) also found that planting double crop soybean into wheat stubble did not affect yield. Grain sorghum was unaffected by wheat stubble, and the effect of delayed planting was not measured in this study; grain sorghum was only planted at the second planting date.
A limitation of this study is that one wheat variety (INW0412) was planted in all the double-crop plots. Tollenaar et al. (1993) reported a variable response of silage corn to four varieties of winter rye, and it is logical that a similar response may be seen with different winter wheat varieties. Also, the soybean yield may have been improved by including a shorter-season (earlier maturity group) soybean variety for the later planting dates.
Uniform plant population was a challenge in this project, due to erratic stand in the wheat stubble plots. This effect could have been reduced by planting the second crops at an angle as opposed to parallel to wheat lines, to reduce the chances of an entire row being planted into the wheat crowns. This was impossible due to adjacent plots in this study, but should be considered for inclusion in future dual cropping system research.
For maximum digestible dry matter production, the second planting date was the most productive. For producers planting at the first planting date, a single crop of silage corn would be most productive. The total system yield change would not justify the added costs associated with wheat production. There are no differences in the second planting date for three double-crop systems: ensiled winter wheat + silage corn, sorghum or sweet sorghum. The agronomic issues associated with sweet sorghum production mean that it is not well suited for production in Indiana. Therefore, forage sorghum or corn would be equally productive. At the third planting date, silage sorghum would be the best choice for total DDM production; there is no yield advantage to producing the riskier sweet sorghum.
Producers in Indiana would reap the environmental benefits of winter wheat as a winter cover crop and no-till production by adopting a forage double-crop system. Harvesting and ensiling wheat at boot stage optimizes both winter wheat and second-crop productivity and digestibility. Yield losses associated with grain production in double crop systems are substantial and the economic analysis indicates that these are only profitable in soybean systems.
Educational & Outreach Activities
Shoaf, S. S., L.J. Unruh Snyder, and C. Dobbins. 2013. Economic and Energetic Analysis of Winter-Based Cropping Systems for Potential Biofuel Industry: Implications of General Trends to Share with Indiana, USA Crop Producers. eSci Journal of Crop Production. 02 (03) 2013. 83-90
Navarro, J.I., S.S. Shoaf, L.J. Unruh Snyder, C. Dobbins, and H. Ohm. 2012. Economic analysis of biomass production utilizing winter wheat double-cropping. Journal of the American Society of Farm Managers & Rural Appraisers. 75(1): 89-97.
Shoaf, S.S., L.J. Unruh Snyder, H. Ohm, T. Vyn, and D. Buckmaster. 2011. Winter wheat and row crop combinations for grain, silage and biomass production. American Forage & Grassland Council Proceedings, June 12-15th French Lick Indiana. pp. 5.
Shoaf, S.S., J. Navarro, L.J. Unruh Snyder, T. Vyn, D. Buckmaster, C. Dobbins and H. Ohm. 2010. Cropping combinations of winter wheat with sorghum, maize or soybean for ethanol feedstock, silage or grain production. ASA, CSSA, and SSSA, Annual Meetings Abstracts [CD-ROM]. Madison, WI. November 1-5, 2010, Long Beach, CA
Shoaf, S.S., L.J. Unruh Snyder, and H. Ohm. 2009. Forage analysis of wheat, sorghum, and corn cropping systems. In Annual Meetings Abstracts [CD-ROM]. ASA, CSSA, and SSSA, Madison, WI. Abstract available: http://acs.confex.com/crops/2009am/webprogram/Paper55473.html
Our hypothesis was that winter wheat based cropping systems will sufficiently compensate for yield loss associated with no-till double cropping in the second crops to generate equivalent economic returns, biofuel and energy yields. The study was conducted in two very different growing seasons in Lafayette, Indiana harvested in the summer of 2009 and 2010. There were three winter wheat harvests (boot, heading and maturity) at which time the second crops were planted.
At the first planting date only the winter wheat and soybean double crop were profitable, while all single crop systems were profitable. Of the systems in which wheat was harvested at boot to be ensiled, (second planting date), soybean was the only wheat double crop which was profitable; it generated a positive return in both years ($59 and $277 ha-1, in 2009 and 2010, respectively). In 2009, in addition to the soybean, the double crop systems of ensiled wheat and silage sorghum or sweet sorghum were also profitable ($69 and $29ha-1, respectively). The only single crop system at this planting date, grain sorghum, was not profitable in either year. At the third planting date (second crops sown following wheat grain harvest) in 2009, none of the systems were profitable, but in 2010, three of five were profitable- the one soybean and two silage sorghum systems.
Therefore, farmers may need to make a balanced decision as to what most benefits
their overall farm operation when deciding to use this operation. Producers in Indiana
would reach the environmental benefits of winter wheat as a winter cover crop and
no-till production before adopting a forage double-crop system. Harvesting and
ensiling wheat at boot stage optimizes both winter wheat and second-crop productivity on a dry matter basis and digestible dry matter basis.
Areas needing additional study
The effect of double cropping silage species with winter wheat has not been studied in Indiana. As demand for protein in the form of meat and milk increases with human population, there will be increasing demand upon acreage to optimize production. There is a need for data to indicate the most efficient use of land for dual-purpose crop production in Indiana.