Organic producers generally rely heavily on tillage for weed control. In contrast conventional producers can utilize no-tillage techniques but must rely on herbicide burn down before no-till drilling crops. This project utilized rotational organic no-tillage where field crops are no-till planted into rolled down cover crop mulch which suppresses weeds until the crop canopy closes providing additional weed suppression.
In 2010 Tim Bock of Wills Daal Farm planted soybeans into five strips each of rolled down rye cover crop and control plots where soil was moldboard plowed/disked. Weed biomass was measured twice and soybeans harvested for yield at the end of the season.
Overall rolled rye effectively suppressed weeds. Weed biomass was significantly higher in cultivated plots compared to rolled plots. On average cultivated plots had 2,217 lb/A of weed biomass versus only 61 lb/A in rolled plots. Due to drought conditions soybeans yields were low overall but significantly higher in rolled rye plots (28.1 bu/ A versus 7.8 bu/ A in cultivated plots).
Planting into rolled down cover crop rye provided good weed suppression. Using fewer passes across the field it saved labor and fuel and allowed for more timely management.
Tilled- annual agriculture, covering over three quarters of global agricultural area , has severely impacted soil fertility, water quality, biodiversity and ecosystem function [2-5]. Currently, twenty per cent of croplands are degraded . Reduced tillage systems are increasingly seen as a solution to soil degradation, increasing soil carbon and decreasing soil erosion . However, no-tillage systems rely on herbicide burn down before crop establishment. These herbicides are generally regarded as benign compared to insecticides, but they remain the largest agricultural pesticide class, accounting for 60 percent of the total amount of pesticide used in 2001 . Rolled down cover crops can provide sufficient weed suppression to allow no-tillage organic production. This technique is relatively simple. Growers plant a fall cover crop mixture of rye and vetch or other appropriate cover crop and roll it down in the spring when covers have reached sufficient maturity to ensure cover crop kill. Then field crops are no-till drilled into the resulting thick mulch.
Many farmers in Northampton and Lehigh Counties have heard about and seen the success of organic rotational no-tillage systems at the neighboring Rodale Institute. However, they state skepticism about the use and practicality of such a technique on a working farm. This project was designed to measure weed suppression and yield in no-till versus tilled systems implemented at the field scale as part of an operating farm.
During the 2009-10 season we will plant pumpkins into rolled rye and a control bare ground treatment and evaluate weed biomass and pumpkin yield. Results will be shared at an extension field day and through local newsletters.
• In spring of 2009 soil will be prepared and a cover crop of rye planted by the farmer counterpart.
• In June of 2009 the cover crop will be rolled down and pumpkins planted by the farmer and his interns.
• In July-Sept 2009 weed biomass samples will be taken and processed by DuPont with the help of one intern.
• In Aug 2009 A Field day will be organized by extension educator DuPont for farmers.
• In Sept 2009 Pumpkin harvest for yield will be done by DuPont and one intern and total harvest will be done by the intern crew.
During the 2009-2010 growing season we plant soybeans into rolled cover crop rye and bare/ cultivated ground and evaluate each treatment for weed biomass and soybean yield. I
• In Sept 2009 the soil will be prepared and cover crops planted.
• In June 2009 the cover crop will be rolled down and soy beans planted.
• June-Aug 2010 weed biomass measurements will be done.
• In Aug 2010 a field day will be organized by DuPont.
• Sept 2010 soybean harvest for yield data will be done by DuPont.
• Oct 2010 statistical analysis and reporting will be done by DuPont.
Unfortunately the cover crop did not establish well in 2009. The stand was patchy and not thick enough to provide weed suppression the following year. Additionally the original collaborating farmer Don DeVault changed farms and was no longer able to collaborate on the project.
Tim Bock from Wills Daal Farm agreed to collaborate on the project in year two. Bock and DuPont were able to complete all field management, data collection and outreach goals in year two with the exception of one cultivation when the ground was too dry.
Field Setup: We broke a 3 acre field up into 10 strips 350’ long and 30’ wide. We paired strips into 5 blocks, each with two strips. Within each block we randomly assigned a strip to either the roll down or cultivated treatment.
Experimental details: On Sept 8, 2009 the entire field was plowed. On Sept 15, 2009 after one pass with a field cultivator, rye was planted at 3 bu/ acre. May 13, 2010 strips were rotary mowed. On May 15, 2010 strips were rotary mowed a 2nd time.
Cultivated plots required more passes than should have been necessary due to late incorporation of the rye cover crop which would have been incorporated in much earlier (late April/ first week of May). It was allowed to reach full biomass to match the timing for rolled plots. On May 15, 2010 the field was disked 5 times with the disk set as aggresivally as possible and then plowed with a bottom plow. On May 16th the field was disked 2 more times because there was still too much residue. On May 17th, one pass with a field cultivator was performed. On May 21, 2010 soybeans (Blue River Hybrids 34A7) were planted in 30” rows every 2” in the row. On May 26th primary cultivation was performed with a Lely rod weeder (tine weeder) set on three (medium aggressive). On June 8th the field was cultivated with a belly mounted cultivator. The second cultivation was omitted due to overly dry and then wet conditions.
Rolled plots required only one pass. Rye was rolled using a cover crop roller and soybeans (Blue River Hybrids 34A7) seeded using a Monosem vacuum every 2” in 15” rows on May 21, 2010.
Data Collection: Weed biomass was collected on July 23, 2010. 3 subsamples of 2.67 square feet were collected in cultivated plots and 5 subsamples in rolled plots. Population counts were taken, counting plants in 3 subsamples 26.5” long. Soybean yield was collected by hand harvest October 21st, 2010, 4 subsamples of .257 m2 per plot. Samples were threshed by hand. Machine harvest data was also taken from entire plots. Tractor scales were used that measure in 50 lb increments. Due to the imprecise quality of the scales only treatment totals are reported.
Rye Cover Crop – The rye established well. Rye cover crop biomass was not different between treatments 1.7 T/A dry matter in cultivated plots and 1.8 T/A dry matter in rolled plots.
Soybean Population – Soybeans populations were much higher in the rolled plots (121,691 plants/A) than in cultivated plots (48,424 plants/A). This was likely due to a higher planting rate. Soybeans were planted every 2”. Cultivated (30” rows) = 104,544 seeds/ A; Rolled (15” rows) = 209,000 seeds/ A. However, we also observed significant deer damage in cultivated plots. In rolled plots soybeans were protected by the mulch until they w ere 5 inches tall and could withstand grazing.
Weed Biomass – Weed biomass was significantly higher in cultivated plots compared to rolled plots. On average cultivated plots had 2,217 lb/A of weed biomass versus only 61 lb/A in rolled plots.
Yield – Due to drought conditions soybeans yields were extremely eradic in the region in 2010. Wills Daal Farm is located on steep shaly ground that was extremely droughty, thus yields were low in both plots. Average yields in rolled cover crop soybean plots were 28.1 bu/ A (+/- and in cultivated plots were 7.8 bu/ A normalized to 14% moisture according to hand harvest. Hand harvest may over estimate yield. Yield measurements based on machine harvest also showed higher yield in rolled plots at 12.5 bu/ A and 7.7 bu/ A in cultivated plots. However due to the fact that the truck scales measured in increments of 50 lbs, yield could have been significantly higher or lower than the measured number and we consider hand harvest data though variable more reliable.
Education & Outreach Activities and Participation Summary
In August 2010 thirteen farmers and 5 service providers attended field day at Wills Daal Farm. Demonstration results were published online through the Rodale Institute’s “New Farm” online journal reaching, and the Penn State Lehigh Valley Sustainable Agriculture newsletter reaching more than 500 farmers.
Of thirteen participating farmers in the Aug 2010 field day (collectively managing over 3,350 acres) 91% learned a moderate to a large amount as a result of this workshop. 50% said they were moderately likely, and 40% extremely likely to adopt a new practice such as roll downed cover crops as a result of the workshop. “I would like to increase my use of roll down,” one participant said.