Field Validation of Soil Solute Profiles in Irrigated Cotton

Abstract

Management of water and fertilizer N are important aspects of cotton production in the desert Southwest. GOSSYM, a cotton growth simulation model, has been used extensively to manage these inputs. Our objectives were to further validate GOSSYM by comparing model‐simulated and measured soil NO‐3‐N profiles, to evaluate GOSSYM's potential as a management tool under irrigated growing conditions in the desert part of the U.S. Cotton Belt, and to address questions about the way GOSSYM simulates NO‐3‐N movement through the soil profile in relation to irrigation water management (which in turn affects prediction of plant growth and development). We compared measured profiles of NO‐3‐N with GOSSYM‐simulated profiles. Soil profile samples were obtained from an existing N‐management field study, a split‐plot within a randomized complete block design. Mainplots were upland and pima cotton (G. hirsutum L. cv. DPL 5415 and G. barbadense L. cv. Pima S‐7, respectively). Subplots were a check (0 fertilizer N) and three other N‐management strategies. The cotton was grown on a Casa Grande sandy loam [fine‐loamy, mixed, hyperthermic Typic Natrargid (reclaimed)] near Maricopa, AZ, in 1994 and 1995. Fertilizer N rates ranged from 0 to 350 kg ha−1 in 1994 and 0 to 392 kg ha−1 in 1995. Soil samples taken to a depth of 120 cm in 30‐cm increments were analyzed for NO‐3‐N. Comparisons of simulated and actual NO‐3‐N profiles revealed tendencies in GOSSYM to overestimate NO‐3‐N leaching out of the effective rooting zone, resulting in simulated N stresses midseason. When GOSSYM simulated an N stress, between 50 and 75% of the simulated soil NO‐3‐N values were greater than the measured values, yet the simulated N stress still occurred. This indicates possible limitations in GOSSYM's ability to adequately predict N uptake by plants. The dynamic soil N portion of the model needs further refinement, particularly for cotton production under irrigated desert conditions.

Intraspecies variation in cotton border cell production: Rhizosphere microbiome implications

“…As such, they comprise a convenient system for analysis of dynamic cellular responses to pathogens and other environmental stimuli under controlled laboratory conditions (Goldberg et al, 1989; Guinel and McCully, 1986, 1987; Gochnauer et al, 1990). Cotton cultivars with altered border cell number can be used in future studies to determine whether such phenomena function in variable root–soil interface properties and in crop performance in the field (Unruh and Silvertooth, 1996a, b; Norton and Silvertooth, 1998). Of particular interest are observations of differential resistance to fungal pathogens including Verticillium and Fusarium (Bolek et al, 2005).…”

Nitrogen Nutrition, Yield, and Quality of Cotton under Varying Nitrogen Application Timings and Planting Dates

“…According to this pattern, N fertilization might not be needed for cotton during the first month. Cotton N use efficiency was enhanced without preplant N application (Norton and Silvertooth, 1998). Ebelhar et al (1996) observed a significant increase in cotton yield when N was applied as two equal splits, one at planting and the other at pinhead square stage in Mississippi.…”