Nitrogen uptake and residual soil N in San Joaquin Valley cotton.
Hutmacher, R. B.; Keeley, M.; Travis, R. L.; Rains, W.; Delgado, R.; Perkins, S.; Weir, B.; Vargas, R.; Wright, S.; Munk, D.; Roberts, B.; Jimenez, M., Jr.; Vail, S. S.; Pflaum, T.;
1998 Proceedings Beltwide Cotton Conferences, San Diego, California, USA, 5-9 January 1998. Volume 1. Year: 1998 Pages: 654-658 Ref: 5 ref.
1998
บทคัดย่อ
The first 2 years of study have been completed in a multi-location study to evaluate the response of a current California Acala cotton variety to applied N under a range of soil types, production conditions, and levels of residual soil N. Total calculated applied N plus changes in soil NO3-N during the period from spring to autumn (planting versus postharvest) ranged from a low of 136 to a high of 252 lbs N/acre across the different N treatments and study locations. At the Westside Research and Extension Center location, USA, the only site (in 1996) with a significant yield reduction with low N applications, average applied N plus depletion of soil NO3-N to a depth of 8 feet averaged 164, 206, 214, and 226 lbs N/acre in the 50, 100, 150 and 200 lbs/N acre treatments in 1996. In 1996, with only one site with a significant yield reduction with decreasing amount of applied N, petiole NO3-N levels during the flowering and boll maturing stages were within levels established as sufficient according to
University of California recommendations for petiole NO3-N during the entire growing season at 6 out of 8 locations. In 1997, there was a broader range of petiole NO3-N levels, with 3 out of the 8 locations showing borderline sufficient or deficient levels during flowering and boll maturation. In 1997, three locations (out of 8 total) showed significant yield reductions at N application levels of 100 lbs N/acre or less.