Effect of organic residues on phosphorus use efficiency in potato (Solanum tuberosum)-pea (Pisum sativum) crop sequence in acid soil

Abstract

An experiment was conducted during 2000-2001 on an acid soil at Shimla, Himachal Pradesh, on 8 organic crop residues and 3 labelled P-carriers for phosphorus-use efficiency in potato (Solanum tuberosum L.) -pea (Pisum sativum L., s.I.) crop sequence. Data from 2 cycles of potato-pea sequence showed a significant effect of superphosphate and diammonium phosphate on potato dry matter (10.94%), P concentration (10.21%) in shoot and its uptake (22.78%).Similarly, organic residues incorporation had a positive effect on dry-matter yield (18.80%) and P uptake (32.3%). Positive effect of organic residue on dry matter production of potato was, however, of higher magnitude (79.5%) in the second year. Radio assay data for % P dff (labelled P derived from fertilizers) and per cent P utilization was 8-10% higher in presence of residues. Tracer data showed 21-30% higher32P assimilation in potato leaves within 35 days of P application. use of rubinia and barley (Hordeum vulgare L., s.I residues increased the32P assimilation in leaves by more than 12% at day 35 after planting of potato. Both dry-matter production and P uptake were closely related to P concentration in leaf at 35 days and per cent 32P assimilation in leaf at 70 days after planting. The post soil analysis after 2 cycles of cropping showed higher soil P availability as evident by increased Bray P (4.1 ppm), water-soluble P (0.08 ppm) and Cr03,-oxidizable P (24.2 ppm). A close relationship of dry-matter production and P uptake with Bray P was obtained. The residual effect of P and organic residues on succeeding pea crop was also in line with that of direct effect as evident by higher pea dry matter production (8.3%) and P uptake (16.1 %) for residues and also 11.6% and 45.5% in case of P applied to potato.