A comparison of the effect of straw incorporation and carbon di oxide enrichment on the growth nitrogen fixation and yield of soybeans
Shivashankar, K.; Vlassak, K.; Livens, J.
Journal of Agricultural Science 87(1): 181-185
ISSN/ISBN: 0021-8596 Accession: 004563990
In a glasshouse pot culture experiment, the effect of adding straw at 3 and 6 t [tons]/ha with and without CO2 enrichment treatments at 1000 mg/l from flowering to the pod-filling stage in open top chambers was evaluated on the growth and yield of soyabeans in relation to N fixation. Nitrogenase activity of the soybean root nodules as determined by the acetylene reduction technique indicated that straw on the average gave significantly 34 and 43% higher nitrogenase activity at 3 and 6 t/ha, respectively, than the controls; CO2 treatments on the average increased the activity by 34% compared with the no CO2 treatments; and the mean nitrogenase activity nearly doubled from 9.7 .mu.g/h/plant in the control to 18.7 and 19.7 .mu.g/h/plant with straw incorporation in conjunction with CO2 enrichment. High correlations were observed between weight of nodules and dry weight of leaves, between dry weight of nodules and grain yield and between dry weight of leaves and grain yield. Incorporation of straw was beneficial in increasing CO2 content of soil air and in improving the growth and development of the plants. Straw can be considered to provide a partial substitute for the expensive CO2 enrichment treatment for improving N2(C2H2) fixation capacity and the general growth and yield of crops.