Nitrogen Management in Organic Processing Tomato Production: Nitrogen Sufficiency Prediction Through Early-season Soil and Plant Monitoring

作者：Bustamante S Castro; Hartz T K^*

来源：Hortscience, 2015, 50(7): 1055-1063.

DOI：10.21273/hortsci.50.7.1055

Organic processing tomato (Solanunt lycopersicum L.) production is a significant industry in California, yet little nitrogen (N) fertility research is available to guide N management. 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 and 2) to investigate the utility of early-season soil and plant N monitoring techniques in predicting seasonal crop N sufficiency. Between approximate to 3 and 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 approximate to 11 WAT was determined as a measure of crop N sufficiency. Growers were surveyed regarding N management practices used and fruit yields achieved. Net N mineralization (N-min,) was measured for 20 fields soils by aerobic laboratory incubation. Carbon mineralization (C-min) in 24 hours following rewetting of air-dried soil and water extractable organic nitrogen (VEON) and carbon (VVE0C) were also determined and evaluated as predictors of N-min. Nitrogen management was primarily based on the application of manure or manure compost in the fall. Organic fertilizers were applied mainly in spring (pre- and post-transplanting). SMN in the top 60 cm at 3 WAT ranged from 6 to 32 mg.kg(-1). About 30% of fields were N deficient by 11 WAT. Sensitivity analysis showed that SMN (whether measured from 0 to 30 or 0 to 60 cm) and leaf N at SWAT correctly predicted late-season plant N status in >60% of the fields. Nmin in 28 days ranged from. 8 to 31 mg.kg(-1), representing an average of 2% of total soil N. Correlation between N-min and C-min was weak (r = 0.44, P = 0.051) while stronger correlations were observed between N; and WEOC, WEON and total soil N (r= 0.63, 0.61 and 0.51, respectively, all P< 0.03). A multiple linear regression model that used 3 WAT SMN (0-30 cm) and WEON as independent variables improved Minn prediction (adj. R-2 = 0.67). Significant fruit yield increase with sidedress N application of feather meal at 5-6 WAT was observed in 2 of 4 field trials, demonstrating the ability to remedy a soil N limitation identified by early-season N monitoring.

• 出版日期2015-7