Nitrogen And Water Management In Organic Vegetable Production In California

Author : Sebastian Jesus Castro Bustamante
Publisher :
ISBN 13 : 9781321608144
Total Pages : pages
Book Rating : 4.6/5 (81 download)

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Download or read book Nitrogen Fertilization Management in Organic Processing Tomato Production written by Sebastian Jesus Castro Bustamante and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic processing tomato production is a significant industry in California, yet little nitrogen fertility research is available to guide N management practices. Nitrogen is often the most limiting nutrient in organic vegetable production systems, especially in high-N demand crops like tomato. A total of 37 certified organic processing tomato fields in the Sacramento Valley of California were monitored during the 2012 and 2013 production seasons, with two objectives: 1) to document current N management practices in organic tomato production; and 2) to investigate the utility of early-season soil and plant N monitoring techniques in predicting seasonal crop N sufficiency, and the need for in-season N fertilization. Between approximately 3-11 weeks after transplanting (WAT) soil mineral N (SMN), leaf N and petiole NO3-N were determined every other week. In 22 fields whole plant N concentration at approximately 11 WAT was determined as a measure of crop N sufficiency. Growers were surveyed regarding N management practices used and fruit yields achieved. Soil N mineralization potential was estimated by aerobic laboratory incubation (28 days at 25 °C) for 20 of these fields. Carbon mineralization in the 24 hour period following rewetting of dried soil (C[subscript min]) and water extractable organic nitrogen (WEON) and carbon (WEOC) were also determined and evaluated as predictors of N mineralization potential. N management was primarily based on the application of manure or manure compost, which was applied in 29 fields in the fall and 2 fields in the spring. Organic fertilizers (feather meal, fish byproducts, guano, etc.) were applied to 2 fields in the fall, 14 fields in the spring before tomato transplanting and 11 fields post-transplanting. An overwinter cover crop was grown in only one field prior to tomato planting. SMN in the top 60 cm at 3 WAT ranged from 6-32 mg kg−1, averaging 16 mg kg−1. Apparent late-season N limitation was common at 11 WAT, with 30% of fields having leaf N below established sufficiency standards, and 36% of fields having whole plant N concentration below the established whole plant critical N concentration. Sensitivity analysis showed that SMN between 10-15 mg kg−1 (whether measured at 0-30 or 0-60 cm) correctly predicted late-season plant N status (sufficiency/ deficiency) in 60-80% of fields; fields below this SMN range were likely to become N-deficient, while those above this range were likely to remain N-sufficient. Leaf N at 5 WAT between 42-50 g kg−1 correctly predicted late season plant N status in approximately 70% of fields. Petiole NO3-N was a less useful diagnostic. Net soil N mineralization after 28 days (N[subscript min28]) ranged from 8-31 mg kg−1, representing an average of 2% of total soil N. Correlation of N[subscript min28] to C[subscript min] was weak (r = 0.44, p = 0.051) while stronger correlations were observed between N[subscript min28] and WEOC, WEON and total soil N (r = 0.63, 0.61 and 0.51, respectively, all p