Search Results

You are looking at 1 - 10 of 11 items for :

  • "nitrogen sufficiency" x
Clear All
Free access

May Elfar Altamimi, Rhonda R. Janke, Kimberly A. Williams, Nathan O. Nelson and Leigh W. Murray

greenhouse tomatoes and cucumbers Gartenbauwissenschaft 57 145 150 Elfar Altamimi, M. 2010 Nitrate-nitrogen sufficiency ranges in leaf petiole sap of pac choi grown with organic and conventional fertilizers. Master of Science, Kansas State University, KS

Free access

Anthony F. Silvernail and Gary R. Cline

The effects of cover crop, tillage, and N fertilization on yields of `Paladin' watermelon (Citrullus lanatus) were analyzed by determining available soil N levels, foliar N content, and relative greenness with a SPAD-502 chlorophyll meter. Analyses from all three analytical procedures identified N deficiencies in watermelon with their respected measurements. Available soil N analyses indicated that soil N levels below 40 mg·kg–1 at vining caused dramatic decreases in yields, while the level needed to ensure maximal yields during the same period was 100 mg·kg–1. Results from foliar and SPAD tests indicated that plants with foliar N levels below 42 g·kg–1 and SPAD readings below 40 SPAD units at anthesis will have suppressed yields. Optimal foliar N levels and SPAD readings required for maximum yields were 50 g·kg –1 and 48 SPAD units, respectively. The main difference among all three N testing procedures was that available soil N analysis was able to detect possible deficiencies two to three weeks before either the foliar or SPAD analysis. Differences in yield between plants from conventionally tilled plots and no-till plots were not significant. However, inorganic N fertilization significantly increased yields in watermelon following both rye (Secale cereale) and mix cover crop treatments. Watermelon yields of plants following the hairy vetch (Vicia villosa) cover crop treatment showed no response to inorganic N fertilization. Of the three cover crop treatments, the addition of N fertilizer had the most effect in the rye treatment.

Free access

S. Castro Bustamante and T.K. Hartz

Organic processing tomato (Solanum 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 ≈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 ≈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 (Nmin) was measured for 20 fields soils by aerobic laboratory incubation. Carbon mineralization (Cmin) in 24 hours following rewetting of air-dried soil and water extractable organic nitrogen (WEON) and carbon (WEOC) were also determined and evaluated as predictors of Nmin. 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 5 WAT 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 Nmin and Cmin was weak (r = 0.44, P = 0.051) while stronger correlations were observed between Nmin 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 Nmin 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.

Free access

H.H. Krusekopf, J.P. Mitchell, T.K. Hartz, D.M. May, E.M. Miyao and M.D. Cahn

Overuse of chemical N fertilizers has been linked to nitrate contamination of both surface and ground water. Excessive use of fertilizer also is an economic loss to the farmer. Typical N application rates for processing tomato (Lycopersicon esculentum Mill.) production in California are 150 to 250 kg·ha-1. The contributions of residual soil NO3-N and in-season N mineralization to plant nutrient status are generally not included in fertilizer input calculations, often resulting in overuse of fertilizer. The primary goal of this research was to determine if the pre-sidedress soil nitrate test (PSNT) could identify fields not requiring sidedress N application to achieve maximum tomato yield; a secondary goal was to evaluate tissue N testing currently used for identifying post-sidedress plant N deficiencies. Field experiments were conducted during 1998 and 1999. Pre-sidedress soil nitrate concentrations were determined to a depth of 60 cm at 10 field sites. N mineralization rate was estimated by aerobic incubation test. Sidedress fertilizer was applied at six incremental rates from 0 to 280 kg·ha-1 N, with six replications per field. At harvest, only four fields showed a fruit yield response to fertilizer application. Within the responsive fields, fruit yields were not increased with sidedress N application above 112 kg·ha-1. Yield response to sidedress N did not occur in fields with pre-sidedress soil NO3-N levels >16 mg·kg-1. Soil sample NO3-N levels from 30 cm and 60 cm sampling depth were strongly correlated. Mineralization was estimated to contribute an average of 60 kg·ha-1 N between sidedressing and harvest. Plant tissue NO3-N concentration was found to be most strongly correlated to plant N deficiency at fruit set growth stage. Dry petiole NO3-N was determined to be a more accurate indicator of plant N status than petiole sap NO3-N measured by a nitrate-selective electrode. The results from this study suggested that N fertilizer inputs could be reduced substantially below current industry norms without reducing yields in fields identified by the PSNT as having residual pre-sidedress soil NO3-N levels >16 mg·kg-1 in the top 60 cm.

Free access

Stephanie E. Burnett, Donglin Zhang, Lois B. Stack and Zhongqi He

P were sufficient for plants grown at all P concentrations (nitrogen sufficiency range = 10 to 60 mg·g −1 ; phosphorus sufficiency range = 2 to 5 mg·g −1 ; potassium sufficiency range = 15 to 40 mg·g −1 ; magnesium sufficiency range = 1.5 to 4.0 mg

Free access

Fernando Ramírez, Thomas L. Davenport, Gerhard Fischer and Julio Cesar Augusto Pinzón

3 is floral-inductive in mango ( Yeshitela et al., 2005 ). Alternately, nitrogen sufficiency achieved by potassium nitrate is considered a possible explanation ( Kulkarni, 2004 ). Another key factor when managing mango flowering is synchronization

Free access

Yun-wen Wang, Bruce L. Dunn, Daryl B. Arnall and Pei-sheng Mao

. Rozbicki, J. 2002 Use of nitrogen sufficiency index for calibration of a chlorophyll meter SPAD-502 readings in winter triticale 709 710 Proc. VII Congress of the European Soc. for Agron. 15–18 July 2002 Cordoba, Spain Seemann, J.R. Sharkey, T.D. Wang, J

Full access

Nicolas Tremblay, Edith Fallon and Noura Ziadi

new tool to determine nitrogen sufficiency in broccoli Acta Hort. 824 121 131 Tremblay, N. Wang, Z. Ma, B.-L. Bélec, C. Vigneault, P. 2009c A comparaison of crop data measured by two commercial sensors for variable-rate nitrogen application Precis. Agr

Full access

Giorgio Gianquinto, Francesco Orsini, Paolo Sambo and Matilde Paino D'Urzo

, R. Bélec, C. Jenni, S. 2009 The Dualex: A new tool to determine nitrogen sufficiency in broccoli Acta Hort. 824 121 131 Tremblay, N. Wang, Z. Ma, B.-L. Bélec, C. Vigneault, P. 2008 A comparison of crop data measured by two commercial sensors for

Full access

Eric B. Brennan

farm to table: The organic vegetable commodity of northern California Sociol. Ruralis 37 3 20 Bustamante, S.C. Hartz, T.K. 2015 Nitrogen management in organic processing tomato production: Nitrogen sufficiency prediction through early-season soil and