Combining Roller Crimpers and Electrical Methods for Termination of Cover Crops in Herbicide-free Reduced-tillage Vegetable Crop Production Systems

Progress report for GS21-253

Project Type: Graduate Student
Funds awarded in 2021: $16,326.00
Projected End Date: 08/31/2024
Grant Recipient: North Carolina State University
Region: Southern
State: North Carolina
Graduate Student:
Major Professor:
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Project Information


Electric cover crop termination holds great potential to increase sustainability of reduced-tillage systems by minimizing the need for herbicides and reducing the disturbance of the soil during traditional cover crop termination practices. There exists a critical need for recommendations for the timing and use of electric cover crop termination in reduced-tillage vegetable systems. The objectives of this project are to fill this need by developing recommendations for and evaluating the economic viability of using electric termination of cover crops in reduced-tillage vegetable systems. Three separate studies will be conducted in sweetpotato, cucumber, and a brassica crop to determine the impacts of electric termination of cover crops on crop yield and quality. Additionally, an economic analysis on the cost/benefit ratio of this technique will be conducted and compared with existing practices to determine the economic viability of electric termination of cover crops. Effective recommendations will be developed and disseminated to growers following the conclusion of these studies, in addition to the development of future research objectives based on the results of this work.

Project Objectives:

1. Develop recommendations needed for electric cover crop termination to optimize vegetable crop yield and quality.

2. Assess the cost to benefit economics for using the electric method of cover crop termination and disseminate research-based knowledge and recommendations through grower meetings, technical extension articles, and refereed journal publications.


Materials and methods:

Objective 1. Three separate studies will be conducted in sweetpotato, cucumber, and a brassica crop with similar experimental methods. Each study will be a 2 x 5 x 2 factorial design with 4 replications. The three factors will be tillage (reduced-tillage or conventional tillage), cover crop type (cereal rye, clover, wheat, daikon radish, Austrian pea) and timing of electric application (once or twice). Nontreated plots will be included for comparison. Cover crop planting date is anticipated to vary depending upon the preceding crop harvest date and local weather conditions.  In general, cover crop planting will occur as soon as possible after harvest and land preparation to maximize biomass production potential.  

Termination of cover crops in traditional tillage plots will follow locally accepted practices with combinations of flail mowing, incorporation with scalloped disc blades, and/or moldboard plow/inversion tillage prior to finish tillage and bed/ridged row formation.  In reduced-tillage plots, cover crops will be terminated in the spring with the Weed Zapper approximately three to four weeks before transplanting and again one or two weeks prior to planting or seeding the crop.  Sweetpotato cuttings will be transplanted with a no-till transplanter designed to reduce cover crop residue disturbance and equipped with a modified press wheel to ensure superior soil to sweetpotato cutting contact. Pickling cucumber and the brassica crop will be seeded onto raised (cucumber) or flat (brassica) beds using a tractor mounted planter.

Cover crop biomass will be quantified by collecting above-ground portions of all plant material in a representative 1 m 2 area at the center of each plot several times between cover crop emergence and cover crop termination.  Cover crop and weeds (if present) will be separated, oven-dried at 70 ℃ and weighed to record shoot dry biomass.  Crop stand count, crop canopy height and length of longest vine (sweetpotato only) will be recorded. Crop vigor and canopy coverage will be assessed visually at 2, 4, 6, 8, 10, and 12 WAT (depending on crop). All crops will be harvested to determine the effect of treatment on yield and quality. For sweetpotato, storage roots will be harvested and graded into jumbo (> 8.9 cm in diam), no. 1 (> 4.4 cm but < 8.9 cm), and canner (> 2.5 cm but < 4.4 cm) and weighed, and the no. 1 class. Storage root shape and volume will be classified using an Exeter optical grader. Cucumber will be harvested 2 to 3 times per week for approximately 3 to 4 weeks and graded into oversized (> 5.1 cm diam), no. 3 (> 3.8 cm but < 5.1), no.2 (> 2.7 cm but < 3.8 cm), and no. 1 (< 2.7 cm) and then weighed. Brassica crop will be harvested as needed and weighed. Data for cover crop biomass, crop establishment and vigor, vine length, and crop yield will be subjected to ANOVA by SAS Proc GLIMMIX.  Cover crop treatments and tillage methods will be treated as fixed effects whereas year, location, and replication within location will be treated as random effects.  Means will be separated using Fisher’s Protected LSD (P < 0.05).

Objective 2. Data from the preceding study will be used in conjunction with the expected input costs for each system to determine the cost to benefit ratio. Inputs costs for cover crop termination methods will be compared to those of typical conventional and organic (when applicable) systems.

Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.