Organic Carbon and Nitrogen Changes in Soil Under Selected Cropping Systems
1986
Zielke, R. C. | Christenson, D. R.
The use of different cropping systems is one means of conserving soil organic matter. This study was conducted to evaluate the effect of 9 yr of selected cropping systems on organic C (WBC), N levels (TKN), and N mineralization characteristics (BMN) of a Charity clay (Aeric Haplaquepts). The six cropping systems consisted of combinations of corn (Zea mays L.), oats (Avena sativa L.), alfalfa (Medicago sativa L.), sugarbeets (Beta vulgaris L.), and navy beans (Phaseolus vulgaris L.). Each crop in each system was fertilized at recommended rates. Cropping systems that contained corn had up to 10% more WBC and 7% more TKN at the time of sampling than systems that did not contain corn. Nitrogen mineralization characteristics correlated linearly with WBC and TKN using S81 soil samples but not with WBC, TKN, or N uptake in a greenhouse study using F81 soil samples. The uptake and response to applied N in the greenhouse indicated that 9 yr of cropping with a particular system had an effect on the N supplying capacity of the soil. Reduced uptake and larger responses to applied N were observed for systems that did not contain corn and that lost larger amounts of C and N over the 9-yr cropping period.
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