Dataset Information

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

ABSTRACT: 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.

SUBMITTER: White KE

PROVIDER: S-EPMC7004306 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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

White Kathryn E KE Brennan Eric B EB Cavigelli Michel A MA Smith Richard F RF

PloS one 20200206 2

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 ...[more]

PMID: 32027701

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Project description:Evaluation of crop N status will assist optimal N management of intensive vegetable production. Simple procedures for monitoring crop N status such as petiole sap [NO 3(-)-N], leaf N content and soil solution [NO 3(-)] were evaluated with indeterminate tomato and muskmelon. Their sensitivity to assess crop N status throughout each crop was evaluated using linear regression analysis against nitrogen nutrition index (NNI) and crop N content. NNI is the ratio between the actual and the critical crop N contents (critical N content is the minimum N content necessary to achieve maximum growth), and is an established indicator of crop N status. Nutrient solutions with four different N concentrations (treatments N1-N4) were applied throughout each crop. Average applied N concentrations were 1, 5, 13 and 22 mmol L(-1) in tomato, and 2, 7, 13 and 21 mmol L(-1) in muskmelon. Respective rates of N were 23, 147, 421 and 672 kg N ha(-1) in tomato, and 28, 124, 245 and 380 kg N ha(-1) in muskmelon. For each N treatment in each crop, petiole sap [NO 3(-)-N] was relatively constant throughout the crop. During both crops, there were very significant (P < 0.001) linear relationships between both petiole sap [NO 3(-)-N] and leaf N content with NNI and with crop N content. In indeterminate tomato, petiole sap [NO 3(-)-N] was very strongly linearly related to NNI (R(2) = 0.88-0.95, P < 0.001) with very similar slope and intercept values on all dates. Very similar relationships were obtained from published data of processing tomato. A single linear regression (R(2) = 0.77, P < 0.001) described the relationship between sap [NO 3(-)-N] and NNI for both indeterminate and processing tomato, each grown under very different conditions. A single sap [NO 3(-)-N] sufficiency value of 1050 mg N L(-1) was subsequently derived for optimal crop N nutrition (at NNI = 1) of tomato grown under different conditions. In muskmelon, petiole sap [NO 3(-)-N] was strongly linearly related to NNI (R(2) = 0.75 - 0.88, P < 0.001) with very similar slope and intercept values for much of the crop (44-72 DAT, days after transplanting). A single linear relationship between sap [NO 3(-)-N] and NNI (R(2) = 0.77, P < 0.001) was derived for this period, but sap sufficiency values could not be derived for muskmelon as NNI values were >1. Relationships between petiole sap [NO 3(-)-N] with crop N content, and leaf N content with both NNI and crop N content had variable slopes and intercept values during the indeterminate tomato and the muskmelon crops. Soil solution [NO 3(-)] in the root zone was not a sensitive indicator of crop N status. Of the three systems examined for monitoring crop/soil N status, petiole sap [NO 3(-)-N] is suggested to be the most useful because of its sensitivity to crop N status and because it can be rapidly analysed on the farm.

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Dataset Information

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

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.

Similar Datasets

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