In this Issue:
- The Roots: New Legume Cover Crop Research
1. Extension Events this Summer
Legume Cover Crops and No-till Corn
Thursday, July 12, from 4 to 6 p.m. at the Center for Environmental Farming Systems (CEFS) in Goldsboro.
Registration is free, but space is limited. Please contact Lisa Forehand to register: firstname.lastname@example.org or 919-513-0954
Organic Crop Farm Tour
Thursday, July 19, from 4:30 to 8 p.m. at Hickory Meadows Organics in Whitakers, NC.
This tour will visit a diversified organic farm growing 400 acres of tobacco, soybeans, sweet potatoes, and cotton. Registration is $10 and includes a BBQ supper.
For more information and an agenda, go to: www.organicgrains.ncsu.edu/Upcomingevents.htm.
Please contact Lisa Forehand to register: email@example.com or 919-513-0954
Organic Grain Research Plot Tour
Thursday, July 26, from 4 to 5 p.m. at the Caswell Research Station in Kinston. You MUST pre-register for this informal tour of all the 2012 organic grain research plots by contacting Molly Hamilton at firstname.lastname@example.org or 929-273-1041.
2. Organic Grain Program Research Trials
by Molly Hamilton, Scotty Wells, and Chris Reberg-Horton
This summer the Organic Grain Program at NC State University has many research projects in the ground. The spring has been tough on our team (and many farmers) as we try to get small grains harvested and at the same time plant corn and soybeans--but, it is nearly done. Here is a synopsis of some of our research projects:
- We continue developing the no-till/roll-kill production system for corn and soybeans. Rye and legume cover crops have been roll-killed and corn and soybeans have been planted into the killed cover crop at multiple research locations in the state.
- We have also planted OVT (Official Variety Trial) soybean plots at three locations. We hope this will lead to more, and better yielding, soybean varieties for organic production in the southeast.
- Finally, a soybean study designed to compliment no-till/roll-kill production looks at nitrogen availability to weeds in a system with a rye cover crop killed before a soybean crop. We know that the killed rye cover crop provides a physical barrier and some allelopathy, but can the decomposing rye (and associated fungal communities) tie up enough nitrogen to deplete its availability to weeds and help keep them from competing with the soybean crop? Since soybeans can fix their own nitrogen, can the reduction of residual N in the system decrease late season weed pressures while continuing to hold back early season weeds? We hope to answer these questions.
We look forward to seeing how these trials turn out and to getting more research-based information out to folks in the state. Join us on July 26 at Kinston (see above events) to see some of these research plots, ask questions, and help direct future research!
3. The Roots: New legume cover crop research
Leguminous cover crops such as crimson clover and Austrian winter pea provide significant quantities of plant residue material that build up the soil organic matter pool and furnish essential plant nutrients such as nitrogen for subsequent field crops. Maintaining soil organic matter in field crop production is crucial as organic matter improves soil nutrient and water holding capacity and overall soil structure. An improved understanding of the persistence of cover crop derived organic matter in the soil can increase our knowledge of the effectiveness of different cover crops in contributing to long-term soil organic matter. Most research involving cover crop residue contributions to soil organic matter has focused entirely on the aboveground portion of cover crops, while the contribution of root systems has been neglected. Cover crop root systems can be quite extensive and their chemical composition tends to favor slower rates of decomposition and longer-term persistence in the soil than above ground residues. Considering their potential to contribute to long-term soil organic matter, it is important that we research the persistence and decomposition dynamics of leguminous cover crop root systems.
Field experiments involving the decomposition of crimson clover, Austrian winter pea, and hairy vetch roots under different cover crop kill methods have been initiated in the last year at the Center for Environmental Farming Systems (CEFS) in Goldsboro as well as in Kinston. The two kill methods that have been employed are disking, which works the cover crop into the soil and roller-crimping, which leaves the cover crop on the surface as a mulch. Root decomposition measurements under these different kill methods will be taken throughout the summer into early fall. The results of this field study will give us a better idea which cover crop species root systems contribute the most to long-term soil organic matter as well as how different kill methods affect the rate and, hence, the long-term persistence of root systems in the soil organic matter pool.
In addition to this field experiment, we also are conducting a greenhouse study comparing the root system morphology (root length and diameter) of crimson clover, Austrian winter pea, and hairy vetch. Past research has indicated that root systems of different diameter classes decompose at different rates with finer roots (small diameter) decomposing much faster than larger roots. There is also evidence showing differences in chemical composition between roots of different diameters with finer roots having a composition more favorable to rapid decomposition. Our hope is that this greenhouse-based root morphology experiment will improve our understanding of which cover crop species have the largest root systems and how these root systems compare to one another in terms of morphology. This can increase our predictive power concerning the rate of root system decomposition of these different species. Preliminary results indicate that crimson clover has the largest root system as well as the greatest proportion of fine roots. We hope to build upon this root morphology research this fall by testing how decomposition is affected by soil nitrogen status.
Given the importance of roots in contributing to long-term soil organic matter, investigating the decomposition dynamics of cover crop root systems is a worthy cause and should provide pertinent information relevant to producers that utilize leguminous cover crops as a component of their soil fertility management program.