Final Report for LS10-230
This three-year research project was to investigate and assess the use of summer cover crops (SCC) in fall/winter vegetable production systems in Louisiana, Mississippi and Alabama on research stations and at collaborating farms. The use of summer cover crops represents a strategy to improve or stabilize soil quality and health and also enhance vegetable crop nutrient management. The specific goals of this project were to: 1) investigate relative productivity and soil building properties of summer cover crops; 2) determine the influence of summer cover crops on subsequent vegetable crop productivity; 3) increase the knowledge base of organic and sustainable producers, extension and educational professionals; and 4) increase the profitability of regional vegetable farmers. At LSU AgCenter’s research station in Baton Rouge and Mississippi State’s research station in Crystal Springs, cover crops were established in the summer and then harvested followed by soil incorporation. A late fall/winter vegetable crop was then established (2010 – cabbage; 2011 – broccoli, 2012 – lettuce) with varying rates of composted chicken litter organic fertilizer. The research in 2010 demonstrated the differences in biomass due to cover crops harvest timing (60 vs. 90 days) with the biomass from the 90 day harvest excessive and creating an in issue with managing harvesting and incorporating of both sesame and Crotalaria. Sesame and the 90 day harvest timing reduced the yield of cabbage while increasing fertilizer positively impacted yields. In 2011 and 2012, cover crops (Sorghum-Sudangrass, sesame, Crotalaria, sesame + Crotolaria) were evaluated. Sorghum-Sudan grass cover crops significantly lowered the yield of broccoli unless combined with increased rates of composted broiler litter fertilizer. All other cover crops had no significant influence on yield, even across broiler litter applications. As the broiler litter fertilizer rate increased, broccoli yield increased within and across cover crops. In 2010, a summer cover crops cultivar screening evaluation was conducted at both locations with 31 entries in unreplicated field trials. The findings included the suitability of Japanese millets and Sorghum-Sudangrass for short-term cover, and the promise of several small seeded legumes. A demonstration plot was conducted in Lorman, AL in 2011 and 2012 with Sorghum-Sudan grass for fall vegetable crops and an on-farm cover crops study in Meadeville, MS in 2010 and 2011 in a fall vegetable rotation. The project showed that several SCC crops have promise for use in vegetable production. Management of SCC in terms of stand establishment, length of growing season, harvest and soil incorporation, and management flexibility are issues that the project addressed in order to provide environmental and economic benefits of using SCC without causing planting delays for the winter vegetable crop.
Determine the relative productivity and soil building properties and soil health of summer cover crops in Gulf Coast organic farming systems.
Determine the influence of summer cover crops on subsequent vegetable crop productivity.
Enhance the knowledge base of area outreach and educational professionals serving the needs of organic and similarly minded farmer-marketers in the Gulf States.
Develop production budgets for the various summer cover crop treatments and the fall organic vegetable crops.
Louisiana, Mississippi and surrounding Gulf States are seeing a large increase in demand for local produce. This is especially evident in the various direct marketing opportunities such as local farmers markets and sales to restaurants. For many small and medium-scale growers in the area, the principal production seasons are the fall through the winter and spring. There is often a fallow period on many vegetable farm fields through the summer months due to extreme high temperatures and drought. This is seen by the lack of local produce during the summer months at local markets. Increasing crop productivity outside of the summer season would improve availability of produce, increase grower income, and enhance the value of farmers markets to their communities. Along with the exponential expansion of farmers markets and other direct market opportunities there has been an increasing trend of new and beginning farmers many of whom are interested in employing sustainable and/or organic production practices on their farms. Investigating sustainable production practices that target the summer months will support many of the small and medium-scale sustainable vegetable farmers with beneficial information and this will also be useful to large-scale wholesale vegetable farm operations.
This project was proposed to study the influence of summer cover crop systems on fall organic vegetable crops for local sales. This is based on preliminary research data on various cover crops grown in the summers of 2007 and 2008 (Evans and Motsenbocker, 2008). Southern soils have high organic matter oxidation rates and are generally low in organic matter; often less than 1 percent. The National Organic Program's (NOP) National Organic Standards (NOS) mandates that farmers implement practices that improve or stabilize soil health (USDA, 2007). Cover crops are often used in vegetable crops rotations as they have direct benefits on soil health properties including organic matter. Numerous reports of the benefits of cover crops have been published over the years. Seigies and Pritts (2006) found that different cover crop species resulted in a myriad of crop ecosystem changes, most of which were positive. Winter cover crops in annual rotations generally are planted in the fall, grow throughout the winter and early spring, and are usually killed before the spring and summer cash crops are planted. In the Gulf States, fall vegetable crops are sown starting in September/October through the fall months and spring vegetable crops are planted in late winter and harvested through the spring with many finishing production in early summer. During this time, summer cover crops could be used to build soil organic matter and improve soil health for fall cash crops.
There have been studies on summer cover crops in other areas of the US but very little research here in the Gulf South. Cramer and Baldwin (2001) published results of a large study of summer cover crops in North Carolina in 2001. They showed large differences in biomass, carbon, and nitrogen dynamics in their test of thirteen cover crop species plus several crop mixtures. Their research was quite thorough and has been informative in planning this study, but their work was done nearly 1000 miles from Mississippi and Louisiana. In addition, the range of USDA hardiness zones in Mississippi and Louisiana is slightly warmer than those of North Carolina, with over 50 inches of rainfall annually (North Carolina Zone 6a to 8a, Mississippi through Louisiana Zones 7a to 9a).
Based on previously conducted research (Louisiana, Mississippi), the team proposed a three-year research project to assess the efficacy of various summer cover crops with differing levels of organic fertilizer on the production of several fall/winter vegetable crops. This research was designed to be conducted at the LSU AgCenter Burden Center and Mississippi State’s Trucks Crop as well as at the Alcorn State University’s research farm and collaborating farms.
2010 Replicated Summer Cover Crop Study: Field experiments were conducted in Baton Rouge, Louisiana to evaluate the growth and yield of cabbage (Brassica oleracea, var. Capitata) transplanted into plots that previously had one of two summer cover crops, Sunn hemp (Crotalaria juncea) or sesame (Sesamum indicum) incorporated in the fall. The cover crops were broadcast at recommended rates at two timings (June 10, 2010, early planting; July 17, 2010 (late planting) into 3.7 by 18.4 m three row plots using untreated seeds and incorporated using a fence harrow. Plots received no irrigation, fertilizer, or pesticides prior to or during growth. On September 15, 2010 a 1 m2 area of cover crop and weed shoot mass was sampled, and the soil sampled. Cover crop plots were harvested 60 and 90 days after planting (DAP) using a forestry cutter and flail mower, and then incorporated by multiple passes of a disk harrow. Cover crop plots were divided into 3 sub-plots 6.0 meters long receiving two rates of composted chicken litter organic fertilizer (166 and 332 kg N per ha) and an unfertilized control. Cabbage was machine transplanted into plots at a 30-cm in-row spacing. The cabbage plots received an initial side-dress application of fish emulsion (1-4-0) after transplanting as well as overhead supplemental irrigation when needed. Pest management was accomplished by an application of B. thurigiensis and weed control through cultivation and hand weeding of plots. The middle ten plants of each sub-plot record row were harvested, graded, and individually weighed in March 2011. In addition, soil and foliar samples were taken at harvest for nutrient analysis.
2011 Replicated Summer Cover Crop Studies: In 2011, field experiments in Crystal Springs, Mississippi and Baton Rouge, Louisiana, the influence of four cover crops: sunn hemp (Crotalaria juncea L. var. sun hemp), sesame (Sesamum indicum L. var. sesame), sorghum-sudan grass (Sorghum X drummondii var. Southland Honey Pasture Hybrid) and a sunn hemp + sesame blend, in combination with four rates of composted broiler litter (CBL) : 0, 1.25, 2.5 and 5 T/acre on fall broccoli (Brassica oleracea, var. Italica cv. Marathon) production was assessed. The Baton Rouge site also had a no cover crop treatment; Crystal Springs did not. The cover crops were established in four replicates, sampled at ~45 days, mowed and incorporated. Four weeks after incorporation, the CBL was applied according to treatment within each subplot, and tilled into the soil before bedding and transplanting of broccoli (cv. Marathon). Soil tests were done pre- and post- cover crop, and after the broccoli were harvested. Leaf tissue samples were taken at the peak of broccoli harvest and analyzed for nutrient concentrations. Broccoli was harvested, counted and weighed in marketable and unmarketable groups.
2012 Replicated Summer Cover Crop Study: In 2012, the study was repeated at both locations with broccoli used again as the fall vegetable crop. The cover crop plots received a single irrigation after planting, but received no fertilizer or pesticides prior to or during growth. A 0.5 m2 area of crop and weed shoot mass was harvested at 60 days. Data collected from the second year of the study included cover crop fresh weight and biomass, total nutrient content, and soil organic matter and nutrient content, along with yield and quality of broccoli.
2013 Replicated Summer Cover Crop Study: In 2013, the study was repeated once more, but this time with lettuce (Latuca sativa L. cv. Nevada) as the fall crop. Leaf lettuce was grown in Baton Rouge, LA and Crystal Springs, MS following summer cover crops. In this third year of a study, four cover crops were raised for during summer 2013: sorghum-sudan (Sorghum X drummondii var. Southland Honey Pasture hybrid), sesame ((Sesamum indicum L. var. sesame), sunn hemp (Crotalaria juncea L. var. sun hemp), and a sesame/sunn hemp blend. After cover crop incorporation in September, lettuce was transplanted at 12 inch spacing onto raised beds 30 to 35 days after the cover crops were flail mowed and incorporated. Prior to transplanting, four rates of broadcast, incorporated composted chicken broiler litter compost were superimposed on each cover crop plot as part of a split plot arrangement. The litter was incorporated and the soil cultivated to form narrow, raised rows 42 inches apart. Four week-old lettuce transplants were set into these rows 12 inches apart and watered in. Lettuce was harvested, counted and weighed in marketable and unmarketable groups.
2010 and 2011 Summer Cover Crop Screening Trial: We have conducted two consecutive years of cover crop screening at the Truck Crops Branch in Crystal Springs, MS. The cover crops tested were for summer production in fallow vegetable land, with the intention of improving the soil prior to growing fall planted vegetables. The focus of the screening was production of above ground biomass under hot conditions with natural summer rainfall after using irrigation for germination and stand establishment. None of the screening trials received fertilizer or other additions. Each year included three replications of small plots of 30 or more entries. Entries were seeded in early summer and biomass sampled from a 0.25 m2 quadrat at early flowering or near 90 days after seeding if they did not flower.
In 2010, a cover crop screening trial was sown in July 2010 into a tilled field. Thirty-one entries, including legumes, grasses, and other crops, were tested in triplicate in a randomized complete block design. Cover crops were hand seeded into moist soil at the high end of recommended and published rates for each entry then lightly incorporated. No fertilizer or additional irrigation was applied. Plots, 10 ft. X 10 ft., were not watered from sowing until termination, and deer predation was heavy on several of the legumes. Each plot was harvested at early to mid-flowering, except those that did not flower during the trial period. These were harvested at the final harvest date or not harvested at all. Harvest dates were Aug. 27, Sept. 22, and Oct. 19. Weeds were separated from cover crop material and the fresh weight of each determined. Dry weights were recorded after drying samples in a forced air oven at 65C until constant weight was achieved.
In 2011, the screening trial was planted into raised bed plots with four replications. Cover crops (31) were hand broadcast at recommended rates on July 22 into 2.4 X 6.0 m plots using untreated seeds. After planting seeds were incorporated using a soil cultivator (Lilliston). Plots received no irrigation, fertilizer, or pesticides prior to or during growth. When the individual cover crops reached full flowering, a 1 m2 area of cover crop and weed shoot mass was sampled and the cover crop and weed biomass calculated.
2011 and 2012 Sorghum-Sudan Demonstration at Lorman: In 2011 and 2012, cooperators at Alcorn State University (ASU) demonstrated the role summer planted sorghum-sudan grass in vegetable crop systems. The ASU team changed shortly after the project began because of the unexpected passing of Reddi Chintha in early 2011. Dr. Girish Panicker agreed to take on the project and has been the ASU lead since. A short-season summer cover crop, sorghum-sudan grass, was grown for two months and clipped down for raising organic broccoli on a Memphis silt loam (Typic, silty, mixed, thermic Hapludalph) in the southwestern part of Mississippi. The research plot was established using a randomized complete block design with four rates of manure; control (no manure), low rate (3,646 kg ha-1), medium (7,291 kg ha-1), and high rate (14,581 kg ha-1) of composted poultry manure. Cultural practices, including manual weeding and irrigation, were applied uniformly to all treatments. Based on the minimum requirements recommended by the USDA/NRCS for conservation planning, biomass development was recorded covering the parameters plant height, canopy height, canopy width, leaf area index (LAI), and percent canopy cover for each treatment thrice during the growth period. The dry upper and lower biomass was recorded after the final harvest of edible portion. Crop residue was analyzed for total dry matter, C:N ratios, and macro and micro nutrients. After the final harvest and decomposition of residues, surface soil was analyzed for macro and micronutrients, carbon buildup, NO3-N, P, OM, pH, and CEC.
2010 and 2011 On-Farm Cover Crop Study – Meadeville, MS: Two years of studies were conducted at the Sullivan Farm (Preston Sullivan) in Meadville, Mississippi to test and demonstrate summer cover crops under commercial farm conditions. The field site had a sandy loam soil, less than 2 % slope, and had been in sustainably-managed vegetable crop production for more than a decade. The field was fallow prior to the 2010 test and in sweet corn prior to the 2011 cover crop seeding. General practices included winter cover crops, integrated pest management, and limited use of pesticides and herbicides. The farmer selected the subset of treatments and the planting arrangement to fit his practices and implements. Among his needs and wants were Catjang cow pea, buckwheat, alyce clover, red ripper cowpea, velvet bean, Partridge pea, and lablab bean. Crops rejected initially included sorghum, millet, and any larger planting of sunnhemp. The final experimental selections included: Sesame, buckwheat, cowpea, sunnhemp, partridge peas, lablab, and alyce clover. Plots were 10 ft. X 20 ft. Cover crop seeds were broadcast by hand into prepared soil and lightly incorporated (+/- 1 inch) in late June. No fertilizers or pesticides were used on the cover crops. At termination, the cover crops were flail mowed and rototilled into the soil. In 2010, the plots were allowed to rest until Sept. 19, when broccoli, cv. Marathon was transplanted into the plots at 18 inches in the row and 42 inches between rows, resulting in three rows per plot. Prior to transplanting, soil samples were taken by collecting five cores/plot from the top six inches of soil. After soil sampling, fertilizer was broadcast 13-13-13 to provide 100 lbs./acre nitrogen, P2O5 and K2O. Plots were also treated with trifluralin at 1.5 pts./acre as Treflan. In order to meet 2011 fall vegetable planting schedules, all plots were harvested at 47 days after seeding, regardless of maturity. They were otherwise handled similarly to the 2010 procedures described above.
2010 Replicated Summer Cover Crop Study: The trial at Baton Rouge produced excellent cover crop growth and subsequent cabbage production. Cover crop stand establishment was good for all of the plots and weeds were less than 5 % of total biomass in all cover crop plots. Cover crops height was highest for the early planted Sunn hemp (3.3 m), compared to late Sunn hemp (2.4 m) and early planted sesame (2.4 m) plot while the late sesame plot was the shortest (1.9 m). Total fresh weights were highest from the early planted sesame and Sunn hemp (1.96 kg.m-2 and 1.92 kg.m-2, respectively) while the dry weight of the early planting of Sunn hemp (0.56 kg.m-2) was greater than the other cover crops treatments. There were no differences in soil organic matter or soil nutrient status at cover crop harvest. Cabbage yield increased with increasing fertilizer rate. The 90 day sesame cover crop treatment produced lower cabbage yield than the sunn hemp treatments across CBL rate.
2011 Replicated Summer Cover Crop Studies: In 2011 at Crystal Springs, sorghum-sudan grass cover crop significantly lowered the yield of broccoli unless combined with increased rates of CBL. All other cover crops had no significant influence on yield, even across CBL applications. As the CBL rate increased, broccoli yield increased within and across cover crops. With respect to broccoli production, there were no significant interactions between the cover crops and the CBL. The data shows that the 2.5 tons/acre composted broiler litter (CBL) to have the best effect on the fall vegetable crop of broccoli in number of heads harvested and head weights, while 5 tons/acre was not significantly better. There was no significant difference in broccoli number and yield among the cover crops, except that sorghum-sudan grass resulted in fewer heads harvested and lower yields.
Soil tests taken after incorporating the cover crops but before applying the CBL did not show any significant differences among cover crop treatments in soil pH, organic matter content or available nutrients (P, K, Ca, Mg, Zn, or S). After application of CLB and production of a late fall broccoli crop, soil tests indicated that cover crop had minimal influences on soil parameters. However, increasing CBL rates led to increased residual P and K availability, with modest elevations in soil pH and organic matter. These changes were not necessarily correlated with broccoli leaf tissue nutrient levels, crop yield or quality.
2012 Replicated Summer Cover Crop Study: There were significant influences of broiler litter compost on broccoli yield, as well as soil and broccoli leaf tissue nutrient concentrations. Cover crops had less influence than the compost fertilizer on broccoli yield, although there was a strong negative influence of sorghum-sudan grass on subsequent broccoli yield. Sunn hemp produced the greatest biomass, greater than that of sesame or sorghum-sudan grass at cover crop harvest. Cover crop treatment did not affect broccoli yield nor was there a significant in interaction with CBL rate. The control unfertilized treatment resulted in no marketable broccoli heads while the 2.5T/acre and 5.0 T/acre plots had the highest marketable yield and marketable broccoli head weights.
2013 Replicated Summer Cover Crop Study: All cover crops at produced well at Crystal Springs in summer 2013. Again, there were few differences in soil attributes due to cover crop. After three years of CBL application, there was an increase in soil test P levels with increasing CBL rates. At both locations, lettuce growth appeared to be impaired when grown after sorghum-sudan within the first two weeks after transplanting. This retarded growth continued through harvest. Increasing rates of CBL helped lettuce to partially overcome the negative effects of the sorghum-sudan but not completely. Almost no marketable lettuce was harvested from sorghum-sudan plots. Sorghum-sudan has well known allelopathic properties and this study provided very sound, regionally-specific evidence of this allelopathy. It also provided significant local educational opportunities for growers and others that might be considering using sorghum-sudan as a summer cover crop for lettuce and perhaps other fall vegetable crops.
2010 Cover Crop Screening Trial: There were significant differences among the harvested entries, and even within selections of sorghum-sudan that will need further study. As in other work we discuss in this report, the screening trial also showed that it is difficult to achieve good stands of large-seeded species under the conditions we had and imposed on the trial. Another significant finding is the potential utility of millets in a summer cover crop system. The millets we tested were ready to till into the soil in less than 40 days from seeding, making them similar to buckwheat, but millet’s produce more biomass and had less weeds than we have seen in summer buckwheat plots in central Mississippi.
2011 Cover Crop Screening Trial: For the second year in a row, many legumes, including sunn hemp, were subject to significant deer predation, reducing yields. Stand establishment of many large seeded entries was hurt by dry conditions at both sites. At Crystal Springs, sorghum-sudan Sugar Grazer II produced more than 23 ton/acre fresh shoot mass. Sesame performed well at both locations. Millets produced less fresh biomass but may have a niche because they mature so fast under our conditions. There were also promising yields and stands from several small seeded legumes, such as sainfoin.
After two years, seedling emergence and deer predation have proven to limit the production of most Vigna selections tested. Pigeon pea has been an exception. Although it did not produce as much biomass as many of the grasses tested, its solid stands resulted in minimal weed growth, another valuable contribution we screened for. Most large seeded legumes have not fared well under these conditions, due to both poor emergence and deer predation. Several millets produced excellent stands, with modest biomass production. Sorghums and sorghum-sudans have done very well in the trials. Sunn hemp has performed well for us, although some deer feeding has been noted.
2011 and 2012 Sorghum-Sudan Demonstration at Lorman: While the percent canopy cover, yield, CEC, and carbon buildup were high for the highest CBL application rate, the total dry biomass and LAI were high for the medium application rate. The product harvested from the control blocks was non-marketable.
2010 and 2011 On-Farm Cover Crop Study – Meadeville, MS: The site was quite dry during the cover crop growing period. Stand establishment of many large seeded entries, all legumes, was hurt by dry conditions. Sesame performed well at the site. Millet produced less fresh biomass than sorghum-sudan entries but may have a niche because they mature so fast under our conditions.
Educational & Outreach Activities
We are currently preparing 2 manuscripts for publication in peer reviewed journals. The working titles are: “The use of summer cover crops and composted broiler litter in fall broccoli production” and “Summer cover crops and composted broiler litter affect fall planted cabbage in Louisiana”.
Theses by students:
Reynolds, S.M. 2012. The use of summer cover crops and composted broiler litter in fall organic vegetable production. Thesis. M.S. Awarded Spring 2013. (Mississippi State University)
Scientific Presentations and Abstracts:
Evans, W.B., S. Reynolds, R. Williams, A. Horton, and C. Motsenbocker. 2014. Summer sorghum cover crop reduces fall lettuce growth and yield. Presented to the Amer. Soc. Hortic. Sci. Ann. Mtng., July 31, 2014. Orlando, FL.http://ashs.confex.com/ashs/2014/webprogram/Paper20293.html (abstr.)
Panicker, G.K., G. Salazar-Mejia, C.E. Motsenbocker, W.B. Evans, and R.S. Mentreddy. 2014. Effect of a Preceding Short-Season Summer Cover Crop in the Biomass Development and Physico-Chemical Changes in a Succeeding Broccoli. Amer. Soc. of Agronomy. Oral Presentation.
Panicker, G.K., G. Salazar-Mejia, C.E. Motsenbocker, W. Evans and R. S. Mentreddy. 2014. Effect of Organic Manure and a Preceding Summer Cover Crop in the Biomass Development and Soil Physico-Chemical Changes in a Succeeding Broccoli. Amer. Soc. Agron. So. Reg. Mtng. Feb. 4, 2014.
Bi, G., W. Evans, M. Gu and V. Cerven. 2012. Effects of cover crops on soil fertility and sunflower production in high tunnels. Proc. So. Nursery Assoc. Res. Conf. 57: 149-151. Poster presented. (volunteered)
Evans, W.B. C. Motsenbocker, R. Mentreddy, G. Panicker, and V. Cerven. 2012 Winners from Two Years of Summer Cover Crop Screening in Mississippi and Louisiana. 2012 So. Reg. Amer. Soc. Hortic. Sci. Ann. Mtng. Oral Presentation. Volunteered.
Evans, W. 2012. SCC 083: A new multi-state research coordinating committee for linking food quality to soil characteristics and management in organic systems. Presented to the Soil Sci. Soc. Amer. 2012. Annual Conf. Cincinatti, OH. Poster. Volunteered. Abstr. 401-56. Http:// scisoc.confex.com/scisoc/2012am/webprogram/Paper75191.html
Evans, W., C. Motsenbocker, G. Panicker, R. Mentreddy, and V. Cerven. 2012. Summer cover crop screenings for fall vegetable production in the Gulf States. Presented to the Soil Sci. Soc. Amer. 2012. Annual Conf. Cincinnati, OH. Poster. Volunteered. Abstr. 238-5.http://scisoc.confex.com/scisoc/2012am/webprogram/Paper72140.html
Reynolds, S.M., W. Evans, C. Motsenbocker, G. Panicker, and R. Mentreddy. 2012. Improving soils with summer cover crops and broiler litter compost in fall organic vegetable systems. Presented to the Soil Sci. Soc. Amer. 2012 Annual Conf., Cincinnati, OH. Poster. Volunteered. Abstra. 151-6. http://scisoc.confex.com/scisoc/2012am/webprogram/Paper72197.html
Evans, W.B., V. Cerven, and C. Motsenbocker. 2011. Summer cover crop growth in a dry year. So. Reg. Amer. Soc. Agron. Ann. Mtng. Feb. 8, 2011. Corpus Christi, TX. Volunteered.
Evans, W.B., V.C. Cerven, C. Motsenbocker, R. Chintha, R. Mentreddy, and G. Panicker. 2011. Screening of summer cover crops for fall vegetable crop production in the Gulf States. So. Reg. Amer. Soc. Agron. Ann. Mtng. Feb. 8, 2011. Corpus Christi, TX. Volunteered.
Motsenbocker, C. W.B. Evans, R. Williams, and A. Morales. 2011. Using summer cover crops for fall vegetable production. So. Reg. Amer. Soc. Hortic. Sci. Ann. Mtng. Volunteered.
Motsenbocker, C.E. and W.B. Evans*. 2010. Summer Cover Crop Performance in the
Gulf States. HortSci. 45(8)(Supplement): S139. Amer. Soc. Hortic. Sci. Ann. Mtng., Palm Desert, CA. (volunteered)
Evans, W., C. Motsenbocker, G. Panicker, R. Mentreddy, and V. Cerven. Summer cover crop screenings for fall vegetable production in the Gulf States. Presented to Southern Sustainable Agriculture Working Group Annual Conference, Little Rock, AR. February 2013. Poster.
Evans, W.B. Some soils are born great, others have greatness thrust upon them. Mississippi Southern Region Master Gardener Conference. May 2, 2012. Attendance 50.
Evans, W.B. Organic Farming. North Mississippi Sustainable Agriculture Group, Holly Springs. April 26, 2012. Audience 12.
Motsenbocker, C.E. Organic Production: Utilizing Cover Crops. USDA NRCS Organic Training and Listening Sessions. Alexandria, LA, November 29, 2011. Attendance 32.
Motsenbocker, C.E. Organic Production: Utilizing Cover Crops. USDA NRCS Organic Training and Listening Sessions. Ruston, LA, November 30, 2011. Attendance 26.
Motsenbocker, C.E. Organic Production: Utilizing Cover Crops. USDA NRCS Organic Training and Listening Sessions. Baton Rouge, LA, December 1, 2011. Attendance 44.
Evans, W.B. Cover crop results in high tunnels. Mississippi Sustainable Agriculture Working Group. Mound Bayou. Feb. 18. Invited oral presentation. Attendance ~ 10.
Evans, W.B., V. Cerven, G. Bi., M. Gu, K. Hood, and R. Little. 2011. An overview of high tunnel research and outreach in central Mississippi. Southern Sustainable Agriculture Working Group Annual Meeting, Chattanooga, TN. Poster. Attendance: +/-250.
High Tunnel Vegetable Production. Mississippi State University Division of Agriculture, Forestry, and Veterinary Medicine Briefing to USDA Deputy Secretary of Agriculture Merrigan. March 24. Invited. Attendance: 30.
Summer Cover Crops, with R. Chintha. Alcorn State University Field Day, Aug. 26, 2010. 40 contacts, 300 attendees.
Evans, W.B. Research on Organic Growing in Mississippi. Mississippi’s Homegrown Sustainability Conference. Gaining Ground Sustainability Institute of Mississippi. July 31, 2010. 30 contacts.
Two field days were held that included the plots at Baton Rouge. The total vegetable grower attendance was estimated to be over 150. Numerous phone calls and internet questions about cover crops and vegetables were received during the life of the project. Data from the Baton Rouge work was presented at the American Society for Horticultural Science (ASHS) annual meeting in summer 2012 as well as the Southern Sustainable Agriculture Working Group. Two field days were held that included the plots at Crystal Springs, and one at Lorman, MS. Total attendance and views are estimated to be over 500 people across these field days. At Crystal Springs, more than 200 direct contacts saw the trial in place, and more than 1,000 additional indirect contacts saw the trial site during the 2010 Fall Flower & Garden Fest. The trial resulted in changes to the 2011 screening trial. Skills developed from these trials have also lead to establishment of winter cover crop trials in our high tunnels.
Dr. Evans and Dr. Panicker received numerous phone and internet questions about cover crops and vegetables during 2012. Data from the Crystal Springs work was presented in the graduate student competition at the American Society for Horticultural Science (ASHS) in summer 2012. Other data was presented to the Soil Science Society of America, the National Small Farmers Conference, the Southern Sustainable Agriculture Working Group, and the Southern Region ASHS annual meeting in 2012, and the Missouri Organic Growers Association. The M.S. student on the project proposed a follow on study to the SSARE Graduate Student Research program. A graduate student completed their field work and received their M.S. degree. In Louisiana, 2 graduate students received training through the project. In general, the cover crops field research trails in Mississippi and Louisiana provide information in order for vegetable growers to make informed decisions on the use of cover crops in winter vegetable production.
Relationships were developed among Alcorn State University, Alabama A&M University, Mississippi State University, and the LSU AgCenter scientists. These have led to co-authorship of additional research proposals among the group and engagement on other research and extension activities.
The project led to the discovery of a cover crop bi-product. Investigations of this are on-going and are supported by other MSU funds, and its Office of Entrepreneurship and Technology Transfer.
The project led to new and strengthened relationships between the partners and the University of Arkansas and the University of Arkansas-Pine Bluff. Initial efforts at joint cover crop studies and proposals have begun.
Some relationships with two NRCS staff have also been developed. We are pursuing some cover crop demonstration projects and have been called on by several growers to help develop cover crop systems. The NRCS has also called upon the group to present to farmers during trainings.
Strong relationships with the local National Center for Appropriate Technology (NCAT) office have developed from this work as well. Two research/demonstration proposals have resulted from that working relationship so far.
The project led to cooperation on a sweetpotato cover crop project in 2012, resulting in a presentation to the American Society for Horticultural Sciences in 2013.
The economic analysis continues as of the publishing of this report. Several soil and tissue samples are still in process and the final economic analyses will incorporate some of that information.
Cover crop use budgets are being developed that will include potential nitrogen contributions to the system, while considering the more traditional measures of tractor time, seed costs, and other management factors.
Our project was very challenging and it was also very interesting at the same time. Working with collaborative farmers gave us an opportunity to tackle some of the issues that farmers had during the implementation of the trials and the use of cover crops in general in a vegetable crops management system. The project was also able to demonstrate the importance of cover crops. In general, cover crops stand establishment was an issue on farm as well as the research stations. In addition, management of the cover crops at harvest and soil incorporation are challenges for farmers especially with the larger biomass summer cover crops (Sesame, Sunn-hemp) and the days to harvest relate directly to biomass.
The farmers attended our field days, and our contact farmer in Mississippi showcased their fields and shared their experiences. They also indicated a need to incorporate cover crops into a crop rotation with vegetables and the variables such as weather that directly impact crop timing and success with cover crops. Farmers expressed a need to use cover crops but the management of summer cover crops is still a challenge and they expressed the need for further study.
From our cooperator at Meadville, Mississippi: “For changes on my place, I've learned more about growing broccoli than before. You have to get it in early, so that the heads are mature before freezing weather. Cabbage is more tolerant of freezing weather by far than broccoli. Cabbage is similar to collards in cold tolerance. The trouble I still have is growing set plants. I cannot find any suitable germination mix locally and I get poor germination of seeds in what I am able to find.
I still grow cover crops. I am mixing more species than before in my cover crop mix. Rather than just one legume and wheat, I now add kale and mustard to the legume and wheat to make a 4-way cover crop mix. I like the idea of summer cover crops but this year spent too much time mowing and trying to keep weeds down to plant any.”
Overall, the interest in cover crops is increasing in Mississippi and Louisiana. Although we cannot specifically point to acreage increased directly attributable to this project, we have increased acreage of crotalaria, sorghum-sudan, and some sesame. Interestingly, sesame has become a cash crop in Mississippi in particular. The project has resulted in several new relationships between members of the research team and marketers of cover crop seeds who indicate increase adoption. The efforts by USDA NRCS to increase cover crop use in row crop operations is increasing demand for information delivery to farmers.
Areas needing additional study
There is a need to improve emergence and stand establishment of large seeded cover crops and to minimize cost and inputs. Most of our larger seeded cover crops, usually legumes, failed to germinate and establish well using the minimal water and labor model that was used for stand establishment. Even pre-irrigating and planting before a rain sometimes failed to provide seeds of crops like pigeon pea sufficiently uniform moisture to germinate and emerge well under the very hot and dry conditions that may occur in the Gulf States in June, July and August. It is possible that a deeper irrigation and one more day of soil rest after an irrigation might improve soil moisture levels over time to allow larger seeds to germinate and emerge consistently in summer. A related aspect is the method of covering seeds and the seed depth after planting. A uniform and accurate seed depth is critical to proper stand establishment.
Our screening trials showing the potential value of millets in very short-duration cover crop situations and needs more study. It is possible that millets could have a place between two warm season vegetables in the southeast, say, tomatoes and fall melons when a grower might only have a window of thirty days to grow a summer cover crop.
After three years of work at both stations in Mississippi and Louisiana, soil organic matter levels did not increase from the use of summer cover crops. An aspect of this is that the ground was not covered during the spring after the fall/winter vegetable season. Covering the soil with spring crops or cover crops may have helped retain or build more organic matter. It is also possible that the relatively short duration of our study did not include enough years to really show increases in soil organic matter.
Our first year work on sesame and crotalaria in cabbage showed the value of a summer legume cover crop. More work will be needed to describe the relative contributions of summer cover crop nitrogen to a system and how other N inputs can be altered to produce the best crops and the best soil quality.
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