Minimum Tillage Vegetable Crop Production in California

Mitchell, Jeffrey P.; Jackson, Louise E.; Miyao, Gene

doi:10.3733/ucanr.8132

Cited by 10 publications

(3 citation statements)

References 11 publications

(6 reference statements)

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“…The relatively mild Mediterraneantype climate allows growers to produce multiple crops such as lettuce and broccoli each growing season. Typical tillage operations prior to planting include subsoiling, several rounds of disking, landplaning, listing beds, and bed shaping [1]. Tillage increases short-term soil aeration, incorporates fresh organic matter in the form of crop residues and exposes soil organic matter (SOM) that was physically protected prior to tillage to microbial attack, consequently increasing mineralization rates and loss of soil C [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Winter cover crops increase readily decomposable soil carbon, but compost drives total soil carbon during eight years of intensive, organic vegetable production in California

et al. 2020

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Maintaining soil organic carbon (SOC) in frequently tilled, intensive organic vegetable production systems is a challenge that is not well understood. Compost and cover crops are often used to add organic matter to the soil in these systems. Compost contributes relatively stabilized carbon (C) while cover crops provide readily degradable (labile) organic matter. Our objectives were to quantify C inputs, and to assess the effects of urban yard-waste compost, winter cover crop frequency and cover crop type on SOC and labile C stocks during eight years of intensive, organic production that usually included two vegetable crops per year in a long-term systems study in Salinas, California. Total C inputs from pelleted fertilizer, compost, vegetable transplant potting mix, vegetable residue and cover crops, including estimates of below ground inputs, ranged from 40 to 108 Mg ha-1 in the five systems evaluated. Following a rapid decline in SOC stocks in year 1, compost had the largest effect on SOC stocks increasing mean SOC over years 2 to 8 by an average of 9.4 Mg ha-1 , while increased cover crop frequency (annual vs. quadrennial) led to an additional 3.4 Mg ha-1 increase. In contrast, cover cropping frequency had the largest effect on permanganate oxidizable labile C (POX-C), increasing POX-C by 26% after 8 years. Labile POX-C was well correlated with microbial biomass C and nitrogen. Compost had the greatest effect on total SOC stocks, while increasing cover crop frequency altered the composition of SOC by increasing the proportion of labile C. These results suggest that frequent winter cover cropping has a greater potential than compost to increase nutrient availability and vegetable yields in high-input, tillage intensive vegetable systems.

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Section: Introductionmentioning

confidence: 99%

Winter cover crops increase readily decomposable soil carbon, but compost drives total soil carbon during eight years of intensive, organic vegetable production in California

et al. 2020

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“…In contrast, winter N leaching losses were high in a modelling study with several organically managed broccoli systems (111 to 343 kg N ha -1 ; depending on organic fertilizer and compost input) and was not reduced by legume-cereal cover crops [ 34 ]. Though non-legume cover crops have the greatest capacity to reduce leaching losses [ 22 , 29 , 33 , 35 ], N mineralization and availability following incorporation is influenced by the C:N ratio of cover crop species [ 32 , 36 ]. Legume cover crops fix atmospheric N, increasing both labile soil N and crop N uptake after termination [ 17 , 37 – 41 ], but their ability to scavenge residual N is limited [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

“…For example, California is the top lettuce and broccoli production area in the U.S., and most of this occurs in the Salinas Valley [ 54 ]. Frequent intensive tillage operations used by Salinas Valley vegetable producers accelerate SOC mineralization and associated N mineralization, thereby increasing the potential for N loss [ 35 , 47 ]. Mass balances for long-term studies such as the Salinas Organic Cropping System (SOCS) experiment–the focus of this paper–provide insights on the interaction of fertility amendments, SOM and cropping system management over time.…”

Section: Introductionmentioning

confidence: 99%

Winter cover crops increased nitrogen availability and efficient use during eight years of intensive organic vegetable production

et al. 2022

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Efficient use of nitrogen (N) is essential to protect water quality in high-input organic vegetable production systems, but little is known about the long-term effects of organic management on N mass balances. We measured soil N and tabulated N inputs (organic fertilizers, compost, irrigation water, atmospheric deposition, cover crop seed, vegetable transplant plugs and fixation by legume cover crops) and exports in harvested crops (lettuce, broccoli) over eight years to calculate soil surface and soil system N mass balances for the Salinas Organic Cropping Systems study in Salinas, CA. Our objectives were to 1) quantify the long-term effects of compost, cover crop frequency and cover crop type on soil N, cover crop and vegetable crop N uptake, and yield, and 2) tabulate N balances to assess the effects of these factors on N export in harvested crops, soil N storage and potential N loss. Results show that across all systems only 13 to 23% of N inputs were exported in harvest. Annual compost applications increased soil N stocks but had little effect on vegetable N uptake or yield, increasing the cumulative soil system N balance surplus over eight years by 999 kg ha-1, relative to the system receiving organic fertilizers alone. Annually planted winter cover crops increased N availability, crop uptake and export; however, biological N fixation by legumes negated the positive effect of increased harvest exports on the balance surplus in the legume-rye cover cropped system. Over eight years, rye cover crops improved system performance and reduced the cumulative N surplus by 384 kg ha-1 relative to the legume-rye mixture by increasing N retention and availability without increasing N inputs. Reduced reliance on external compost inputs and increased use of annually planted non-legume cover crops can improve efficient N use and cropping system yield, consequently improving environmental performance.

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Degraded Soils

Osman¹

2018

Management of Soil Problems

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Minimum Tillage Vegetable Crop Production in California

Cited by 10 publications

References 11 publications

Winter cover crops increase readily decomposable soil carbon, but compost drives total soil carbon during eight years of intensive, organic vegetable production in California

Winter cover crops increase readily decomposable soil carbon, but compost drives total soil carbon during eight years of intensive, organic vegetable production in California

Winter cover crops increased nitrogen availability and efficient use during eight years of intensive organic vegetable production

Degraded Soils

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