Response of Acala cotton to nitrogen rates in the San Joaquin Valley of California.
The responses of Acala cotton (Gossypium hirsutum L.) in California to a range of applied nitrogen (N) treatments were investigated in a 5-year, multisite experiment. The experiment's goals were to identify crop growth and yield responses to applied N and provide information to better assess the utility of soil residual N estimates in improving fertilizer management. Baseline fertilizer application rates for the lowest applied N treatments were based on residual soil nitrate-N (NO3-N) levels determined on soil samples from the upper 0.6 m of the soil collected prior to spring N fertilization and within 1 week postplanting each year. Results have shown positive cotton lint yield responses to increases in applied N across the 56 to 224 kg N/ha range in only 41% (16 out of 39) of test sites. Soil NO3-N monitoring to a depth of 2.4 m in the spring (after planting) and fall (postharvest) indicate most changes in soil NO3- occur within the upper 1.2 m of soil. However, some sites (those most prone to leaching losses of soluble nutrients) also exhibited net increases in soil NO3-N in the 1.2- to 2.4-m depth zone when comparing planting time vs. postharvest data. The lack of yield responses and soil NO3-N accumulations at some sites indicate that more efforts should be put into identifying the amount of plant N requirements that can be met from residual soil N, rather than solely from fertilizer N applications.
Hutmacher
R B
RB
Shafter Research and Extension Center, University of California, Shafter 93263, USA. rbhutmacher@ucdavis.edu
Travis
R L
RL
Nichols
R L
RL
Rains
D E
DE
Roberts
B A
BA
Weir
B L
BL
Vargas
R M
RM
Marsh
B H
BH
Wright
S D
SD
Munk
D S
DS
Munier
D J
DJ
Keeley
M P
MP
Fritschi
F
F
Delgado
R L
RL
Perkins
S
S
D002140:California; D005308:Fertilizers; D003368:Gossypium / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D006358:Hot Temperature; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism* / Q000494:pharmacology*; D011891:Rain; D012987:Soil / Q000032:analysis; D013997:Time Factors
D005308:Fertilizers; D009566:Nitrates; D012987:Soil; D009584:Nitrogen