Dry Weight and Nitrogen Content of Chickpea and Winter Wheat Grown in Pots for Three Rotations

Abstract

Chickpea [Cicer arietinum (L.)] cultivars 'ICCV-2' and 'Sarah' were studied along with a control, multistrain, TAL 1148, and TAL 480 Bradyrhizobium strains to determine the effect(s) of cultivar and inoculum on dry weight (DW) and nitrogen (N) content of the legume, as well as soil mineral N, DW, and N content of wheat [Triticum aestivum (L.) emend. Thell.] in a continuous wheat-legume rotation. Chickpeas were planted during the summer and harvested in the fall of 1992, 1993, and 1994. Vegetative growth from chickpeas was incorporated into the soil prior to wheat planting, and soil cores were taken at 35 to 48 d after chickpea harvests. Additional summer fallow treatments for the winter wheat part of the experiment received 0, 45, and 90 kg N ha −1 each year. Wheat plants were removed the following spring and stubble was incorporated into the soil before planting chickpeas in the summer. 'Sarah' chickpeas accumulated about the same or more shoot DW and shoot N compared to 'ICCV-2'; whereas 'ICCV-2' generally produced more pod DW and pod N compared to 'Sarah.' Inoculum had no significant effect on chickpea DW or N content. Wheat DW and N following legumes increased marginally after growing 'Sarah' chickpeas, as evidenced by higher values of some treatments. Only the multistrain or absence of inoculum in 'Sarah' chickpeas resulted in significantly greater wheat DW or N content compared to the fallow wheat receiving no added N fertilizer. The contributions from 'ICCV-2' chickpeas to wheat DW and N content were not significant. Soil mineral N, as well as wheat DW and N content, fluctuated or increased during this three-year study, which demonstrated some benefit from incorporation of chickpeas into a wheat-legume cropping system.

Influence of Tillage Systems, and Forms and Rates of Nitrogen Fertilizers on CO2 and N2O Fluxes from Winter Wheat Cultivation in Oklahoma

“…Additionally, the flux rates from cowpea treatments were significantly lower than from the 45-N and 90-N treatments. These results corroborate the previous findings in the region, as poor growth and yield responses of winter wheat to legume-based green N are reported frequently [3,4,25,27,28]. Lack of interaction effects between the tillage systems and N treatments indicated that cowpea-based green manure could not replace inorganic N fertilizers in either tillage system.…”

“…Canopy fluxes of CO 2 increased with increasing rates of N fertilizer, which indicated strong growth responses of winter wheat to amounts of applied N fertilizer. Increased GPP fluxes with increasing level of N fertilizer corroborate results from previous studies in the SGP, where most studies reported strong positive responses of grain or forage yield of winter wheat to amount of applied N fertilizer [4,24,25]. The results of canopy CO 2 fluxes also corroborate results on crop growth and yield of winter wheat, which was reported in a parallel study [26].…”