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Effect of Soil Type on Cotton Residue Mineralization Under Controlled Incubation

B. A. Roberts, F. B. Fritschi,R. L. Travis and W. D. Rains


 
ABSTRACT

A Panoche clay loam (West Side Field Station, Site 1) and a Wasco sandy loam (Kings Co., Site 2) were incubated under controlled temperatures of 10 and 25°C for 203 days to evaluate the differences in microbial biomass activity, quantity and mineralized N. Soils from each site were collected from N rate plots established in 1998. Soil N levels of 50 and 150 lbs./a N included residual N in the top 2 feet plus supplemental urea. The soil used for this study was collected after the 1998 cropping season. This was the first cotton crop following a winter cereal rotation at Site 1, whereas Site 2 had been in continuous cotton. Labled cotton residue produced from 15N microplots at each site was added as substrate prior to incubation. During the 203 day incubation period seven samplings occurred. At each sample date, net N mineralized was determined and additional chloroform fumigation incubation (CFI) analysis was performed to assess microbial biomass carbon and N. CO2 measurements were performed using infrared gas analysis (IRGA). KCl extracts were analyzed for mineralized N (NO3 and NH4) by the DANR Analytical Laboratory, U.C. Davis. Phospholipid fatty acids analysis (PLFA) was performed to compare the microbial community structure.



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pg. 1388
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000