Location: Crop Improvement and Protection Research
2019 Annual Report
Objectives
The long-term objective of this project is to help farmers economically integrate cover crops into tillage-intensive vegetable and strawberry production systems, maximize the benefits from cover cropping, and reduce production costs. This experiment will produce knowledge of short-term (1-2 years) and longer-term (>5 years) effects of cover crops and compost on yield and profitability, soil quality, and pest management, and will be used to make recommendations of optimal rotations. Organic and conventional farmers in California and elsewhere who use cover crops in high-value vegetable and strawberry cropping systems will benefit directly from the results of this research. The research will occur on the USDA-ARS Salinas certified organic research farm in collaboration with local organic farmer cooperators. This research applies to organic and conventional farms that are working to develop more efficient and climate-smart soil management strategies for high-value horticultural crops.
Objective 1: Develop ecologically-based soil management strategies for organic vegetable and strawberry production systems that enhance soil quality, nutrient cycling, pest and disease management, profitability, and reduce off-farm inputs.
Subobjective 1A: Evaluate the effects of cover cropping frequency and compost on soil quality, vegetable and strawberry yields, and system profitability.
Subobjective 1B: Evaluate the effects of a legume-rye mixture versus non-legume cover crops on vegetable and strawberry yields.
Subobjective 1C: Evaluate the effects of cover crop seeding rates on weed densities and weed management costs in subsequent vegetable and strawberry crops grown in rotational sequences.
Subobjective 1D. Evaluate the effects of cover crop type and seeding rate on soil water storage during winter cover cropping.
Subobjective 1E. Evaluate the effects of legume-rye cover crop seeding rate on legume component biomass production.
Approach
Subobj. 1.A. Hypotheses. 1.A.1 -Soil quality will be higher in systems where cover crops are used annually than in systems where they are used only quadrennially. 1.A.2 -Soil quality will be higher in systems that receive compost annually than systems that only receive cover crops. 1.A.3 - Vegetable and strawberry yields will be higher in systems where cover crops are used annually than in systems where they are used only quadrennially. 1.A.4 -Vegetable and strawberry yields will be higher in systems that receive compost annually than systems that only receive cover crops. 1.A.5 -Profits will be higher in systems where cover crops are used annually than in systems where they are used only quadrennially. 1.A.6 -Profits will be higher in systems that receive compost annually than systems that only receive cover crops.
Subobj. 1. B. Hypothesis 1. B -Vegetable and strawberry yields will be higher following legume versus non-legume cover crops.
Subobj. 1.C. Hypotheses. 1.C.1 -Weed density will be lower in vegetable and strawberry systems where cover crops were planted at relatively high seeding rates over several years, than when using lower seeding rates. 1.C.2 -Weed management cost during vegetable and strawberry production will be lower in rotations where cover crops were planted at relatively high seeding rates over several years, than when using lower seeding rates.
Subobj. 1.D. Hypothesis. 1.D1 -Planting cover crops at higher seeding rates will reduce soil moisture early in the winter relative to cover crops planted at lower seeding rates, but over time these differences will decline as cover crop shoot biomass differences dissipate.
Subobj. 1.E. Hypothesis. 1.E.1 -Planting cover crops at higher seeding rates will increase competition relative to those planted at lower seeding rates, and will alter biomass production of the various legume components.
Experimental approach:
These subobjectives will be addressed in the Salinas Organic Cropping Systems experiment that began in 2003 and is the longest running trial in the U.S. focused on high-value, tillage intensive organic production systems. It includes 8 systems that for the first 8 years differed in cover cropping frequency, cover crop type, cover crop seeding rate, and compost rate. The experiment has 2 phases: the “intensive phase” for the 1st 8 years when management differed between systems, and the subsequent, and current “legacy phase” that monitors residual effects from the intensive phase. Commercial scale vegetable production was the focus during the intensive phase whereas vegetables and strawberries are grown during the legacy phase. Data is collected on weeds, soil health, cash crop yields, cover crop services, and economics. The results of analysis from the first 15 years of the trial may indicate that there would be value in collecting additional field data during the remainder of the legacy phase or conducting additional analyses of archived soil samples. If this occurs we will modify our plan to collect this additional data with our existing collaborators or seek additional collaborations as needed.
Progress Report
This report documents progress for project 2038-21620-014-00D, which started in October 2018 and continues research from project 2038-21620-013-00D, "Strategies to Improve Soil and Pest Management in Organic Vegetable and Strawberry Production Systems."
In support of Objective 1, research continued to develop ecologically-based soil management strategies for organic vegetable and strawberry production systems that enhance soil quality, nutrient cycling, pest and disease management, profitability and reduce off-farm inputs. This occurred on certified organic land at the ARS and on collaborating farms, and is applicable to small, medium and large-scale organic farms and to conventional farms that are shifting to more sustainable soil management practices. The majority of this effort occurred within the ongoing Salinas Organic Cropping Systems (SOCS) experiment that investigates crop rotations, soil fertility management, weed management, and the effects of organic matter inputs from cover crops and compost in high-value organic vegetable and strawberry systems. The SOCS experiment is currently in its 16th year and is the longest running systems experiment in the U.S. focused on high-value, high-input organic crop production. This year, ARS researchers at Salinas, California, worked collaboratively with ARS researchers in Beltsville, Maryland, and scientists from other agencies, to evaluate changes in soil organic matter in this long-term study and to understand how these changes were affected by cover cropping and compost inputs.
Accomplishments
1. Novel planter developed for small-seeded plants. Precision seeding of herbs, vegetables and other species with extremely small seeds that are the size of salt grains can be difficult with standard planters. Small seeds are often pelleted in order to plant them with precision, but this process is expensive. An ARS researcher at Salinas, California, developed a simple planter, called the Slide Hammer Seeder, for precision, hand seeding of unpelleted (raw), small-seeded species. The planter works well for seeding a variety of small-seeded herbs and vegetables and has been used to inter-seed sweet alyssum plants in vegetable crops. Sweet alyssum helps to control pest aphids on many vegetable crops and this novel seeder can help farmers do this efficiently.
Review Publications
Brennan, E.B. 2018. The slide hammer stick seeder – a novel tool for planting small seeds. HortTechnology. 28:764-775. https://doi.org/10.21273/HORTTECH04122-18.
