Integrating no-till and forage radish cover crops for sustainable early sweet corn production

Integrating no-till and forage radish cover crops for sustainable early sweet corn production

Summary

Fall-planted forage radish cover crops have shown successful suppression of winter annual weeds and spring pre-plant weed growth as well as recycling of fall-captured nutrients. Data from this research will be used to develop an innovative no-till production system for early sweet corn to take full advantage of the benefits of a fall-planted forage radish cover crop. Cover crop treatments include forage radish, a mix of forage radish and oats, a mix of forage radish oats and peas, and no cover crop.  

Experiment 1 researches the effects of forage radish cover crops on nutrient cycling and soil fertility. In fall, cover crop biomass and soil nitrate scavenging will be measured. In spring, soil temperatures and soil nutrient availability will be measured. Sweet corn yield and quality and will be evaluated, along with soil samples, at harvest in late July. Experiment 2 is focused on the duration of weed suppression provided by forage radish cover crops.

Cover crop plots were planted in August 2014 and measured just prior to winter-kill in mid-November, and sweet corn was no-till planted into the plots in May 2015. Sweet corn harvest and final soil samples were taken in eary August 2015.  This first year of these experiments was successful, with thousands of measurements taken, and early results.

• Research Block 2015
• Cover Crops, October 2014

Objectives/Performance Targets

Our objectives are to:

1. 1. Measure the effectiveness and duration of spring weed suppression by forage radish on subsequent sweet corn crop.  Year one complete. Fall 2015 cover crops are planted in preparation for spring 2016.

1. 1. Determine if the precocity of sweet corn planting and maturity can be improved by a preceding forage radish cover crop.  First year results indicate that spring soil temperatures are affected by forage radish cover crops. The soil temperature of Oat/Forage Radish and No cover crop plots were significantly warmer than those of Pea/Oat/Forage Radish and Forage Radish monoculture.

1. 1. Assess the feasibility and success of earlier planting of sweet corn into a no-till seed bed following winter-killed forage radish cover crop mixes. Year one complete.  Sweet corn was successfully established.

1. 1. Measure the sweet corn yield and date of maturity to determine the effectiveness of a forage radish/sweet corn cropping rotation for producing high quality, early sweet corn. Year one complete.  Initial results indicate that sweet corn following all cover crop treatments yielded competitively.  Oat/FR mixture provides best nutrient syncrony for sweet corn.

1. 1. Provide information relevant to both organic and conventional sweet corn producers, as well as no-till producers. Research overview posted on UMass Extension website. Articles written for UMass VegNotes Newsletter (August 2015) and UMass Crops, Dairy, Livestock, and Equine Newsletter (Summer 2015).

1. 1. Conduct outreach through individual communication, grower meetings and conferences, annual field day events, newsletters and cooperative extension.  Research and results shared at UMass Plant Biology Symposium (October 2015) and Northeastern Plant, Pests and Soil Conference in Philadelphia, PA (January 2016). Met in the field with researchers from Japan to discuss research.

Accomplishments/Milestones

The first year of this project was very successful, while of course there were some challenges. Cover crop treatments, planted in late August 2014, consisted of three different forage radish mixes: all forage radish (FR), oats/forage radish(O/FR), and peas/oats/forage radish (P/O/FR) plus a control of no cover crop (NO CC). Cover crops established successfully and grew well in the fall of 2014. Fall weed population and cover crop biomass were measured just prior to winter-kill in mid-November 2014. There was significant variation between the 4 replicates, which made it difficult to compare cover crop biomass and seems to have mitigated some of the differences we had hoped to observe. Soil samples were also taken in mid-November, and results showed that all cover crop treatments successfully scavenged soil nitrate down to 60 cm, compared with No CC.

Experiment 1: Nutrient cycling

In Experiment 1, early sweet corn is no-till planted following the afore-mentioned cover crop treatments. In spring, soil temperatures are measured for 2 weeks, from late April to early May 2015, and compared among cover crop treatments. Soil was significantly warmer in plots of O/FR and NO CC, compared with FR and P/O/FR treatments.

Three nitrogen fertility treatments are used to examine the synchrony between nutrient release from decomposing cover crop and the uptake by sweet corn will be measured. Fertility treatments include:

• • 0 lbs N/acre

• • 0 lbs N/acre at planting and 25 lbs N/acre side-dressed

• • 25 lbs N/acre at planting and 25 lbs N/acre side-dressed

Sweet corn ‘Trinity’ was seeded in early May after plots were sprayed with a burn-down application of RoundUp. In June, high populations of European Corn Borer were observed in plots above IPM threshold levels. Plots were sprayed with Dipel, a Bt product, and the application was repeated 10 days later. In mid-June the side-dressed nitrogen treatments of urea were applied. Sweet corn plots were protected from raccoons with electric fencing.

Sweet corn was harvested twice, on July 30 and August 4, 2015. Fresh weight, number of ears, and tip fill were measured. Some raccoon damage occurred, but there was sufficient plot area to have a representative harvest. Results showed that nitrogen treatment had no effect, presumably because of the low rate of nitrogen applied. FR achieved highest sweet corn yields, although not statistically different than O/FR and P/O/FR. All cover crop treatments yielded significantly more sweet corn by count and by weight than NO CC, and all yielded within an optimal range in terms of ears per acre.

Soil samples were taken April 27, May 18, June 14 and August 3, 2015. Soil nitrate analysis has been conducted (see Tables 1-4), and I am currently running analysis on soil concentrations of other elements (Ca, Mg, P, and K).

Experiment 2: Weed Suppression

In Experiment 2, there was a major change of experimental design. Originally, we had proposed three weed management methods including herbicide application, flaming, and no-till cultivation. However, the fall cover crop biomass was substantial due to the early planting date and optimal fall growing conditions. In the spring, cover crop residue was much thicker than expected. When we tried flaming, the plot caught on fire. Cultivation was also deemed impractical because the oat and oat/pea residue was too thick for a finger-tine cultivation. So there remained an herbicide treatment, and a control.

The first measurement of spring weed biomass was taken on April 29, 2015. The lowest weed biomass occurred under the forage radish cover crop treatment. Compared with forage radish, the weed biomass was 25% greater in the Oat/FR and 60% greater Pea/Oat/FR treatments. Unfortunately, in early May this experiment was accidentally sprayed with RoundUp, and all weeds were killed. I had originally planned to measure spring weed biomass at least three times, through the end of May. So for the first year of the experiment I only have one data point. This is disappointing, but still significantly useful information because it was just one week prior to sweet corn planting, when growers would be making decisions about herbicide applications. I look forward to seeing more data in the spring of 2016.

Next Steps:
Work that remains to be done on first year research includes statistical analysis of interrelated variables, such as soil nitrate, cover crop treatment, and date of sampling. Soil phosporus analysis will be conducted on stable, dried soil samples. Nitrogen sufficiency tests (CSNT) need to be performed on dried sweet corn stalks and marketable yield will be calculated. 

The second year of this research has already begun. Cover crop plots were planted in late August 2015, after baseline soil samples were taken. Fall 2015 cover crop biomass was harvested twice, in October and again in December 2015. It has been dried and now needs to be weighed and ground for tissue analysis.

In no-till systems soil improvement tends to progress slowly. One year of treatments may not be sufficient to measure improvements by looking via traditional indicators, like soil organic matter. I am looking for additional assays that may indicate early stages of soil improvement, such as beta-glucosidase or humic acid content.

Milestones, 2014-15

2014:

August 18: Fall soil samples collected from all plots

August 23: Planted forage radish cover crops for Exp. 1: nutrient cycling experiment

August 28: Planted cover crop mixes for Exp. 2: weed experiment

November 10: Harvested and weighed cover crop biomass and weed biomass

2015:

April through May: Soil temperatures measured

April 27: Soil sampling, round 1

May 7: Sweet corn planted (variety: ‘Trinity’)

May 13: Nitrogen treatments applied

May 18: Soil sampling, round 2

June 14: Soil sampling, round 3

June 16: Dipel sprayed for European Corn Borer

June 18: Side-dress N treatments applied

July 30 and August 4: Sweet corn harvest

August 3: Final soil sampling

Milestones, 2015-16

2015:

August 14: Fall soil samples collected from all plots

August 24: Planted cover crops, both experiment for Year 2

October 27: Soil samples collected and dried

October 23: Harvested and weighed cover crop biomass and weed biomass

December 4: Harvest final cover crop biomass samples and dry

Planned for 2016:

January and February 2015: Lab analysis of remaining 2015 samples (corn stalks, soil phosphorus)

March: Purchase corn seed & fertilizer, hire summer help

April 2015: Measure soil temperature, measure weed germination, soil sampling

May 2015:  Plant corn based on soil temperature, measure weed growth

June 2015: Monitor weed growth, conduct weed control, soil testing, PSNT

July 2015: Harvest sweet corn, measure yield, CSNT, conduct soil testing, present the results at UMass Annual Field Day

August 2015: Analyze samples in lab, data analysis

September-November 2015: Data analysis and end of project report

• Cover Crop Planting 2015
• A Beautiful Forage Radish
• UMass Agricultural Field Day, July 2015
• Sweet Corn Harvest and Data Collection, August 2015

Impacts and Contributions/Outcomes

This year I presented this research at several events and through several publications (see list concluding this section). Recently, I presented my research in the graduate student poster session at the Northeastern Plant, Pest, and Soils Conference in Philadelphia, PA. I spend the two-hour poster session talking with a dozen researchers about my hypothesis and results, which felt fruitful and informative. The UMass Agricultural Field Day in July allowed me to share my research and initial results with nearly 100 farmers and agricultural service providers. Two articles published through UMass extension newsletters were sent to thousands of growers. I had an amazing experience learning and discussing my research with other attendees at the Cornell Soil Health Workshop in August.

Activities over the last year have contributed to sustainable agricultural practices in several ways. First, the initial results show very clearly the nitrogen scavenging benefits of cover crops. While this isn’t revolutionary news, it is powerful to show the effect in practical cover crop mixtures that growers can easily use in our area. Second, this research has encouraged conversations and debates about cover cropping and no-till practices. In this area farmers and gardeners are interested in forage radish cover crops, but haven’t necessarily seen them in practice. No-till is not widely used in Massachusetts, yet people are interested in learning more about it to improve soil health and conservation.

The data on spring soil nitrate is very important to describe how we can select cover crop mixtures to increase the synchrony between cover crop nutrient release, and the demand of the following cash crop. Beyond the measurable and statistical observations, now we can describe what these cover crop mixtures behave and how to use them in this region. For example, forage radish is promoted as a low-residue cover crop. When it is mixed with oats, the spring residue has significant ground cover that could either be an advantage or disadvantage depending on management practices.

I believe the results of this research will help farmers make good choices about how to select cover crops for sweet corn production systems, and will provide data on achievable yields in no-till systems.

Presentations & Publications:

• Fine, JS Research Poster for NEPPSC Conference

Collaborators: