Utilization efficiency of applied nitrogen as related to yield advantage in maize/mungbean intercropping

Abstract

Utilization of nitrogen is of particular interest in legume/non-legume mixtures. An experiment was conducted on Ultic Haplustalf soil at Los Banos (14° 11′N, 121° 15′E) to determine the effects of rhizobial inoculalation and nitrogen applied at 0, 30, 60 and 90 kg ha-1 on growth and performance of intercropped maize and mungbean, and to relate nitrogen use to the yield advantage. Inoculation decreased both dry matter and grain yield of intercropped maize and mungbean. Applied N at levels above 30 kg ha-1 increased the dry matter and the grain yield of maize but reduced that of the associated mungbean. Intercropping drastically reduced the dry matter yield of mungbean but maize showed negligible reductions; the reductions were evident when the crops flowered. Inoculation increased the land equivalent ratio (LER) by increasing the partial LER of maize. Applied N at high levels also increased the partial LER of maize but this failed to increase LER due to corresponding reductions in partial LER of mungbean. Nitrogen at 30 kg ha-1 produced the highest LER (1.40). Applied N increased N uptake of maize but decreased that of mungbean. Inoculation increased the N uptake of both mungbean and maize at 48 days and onward. Large reduction in N uptake of intercropped mungbean was observed when it flowered at 33 days but maize was affected 2 weeks later at the tasseling stage. Thus, the competition for N was acute when the crops were at the reproductive stage. The LER analysis in terms of N utilization efficiency showed that N absorption efficiency of both maize and mungbean was reduced due to intercropping, and mungbean was more affected than maize. Increase in applied N caused a higher reduction in N absorption by mungbean although it increased the N absorption by maize. The change in total N absorption by maize and mungbean in intercropping over that of the sole crops together, was positive in all instances, meaning higher total N absorption in mixed stand of crops than in pure stands. The N conversion efficiency, measured as the amount of grain produced per unit of N absorbed, decreased in maize due to intercropping but increased slightly in mungbean. The absorption term contributed more to the increase in LER over unity than the conversion term. © 1992.

Source or Periodical Title

Field Crops Research

ISSN

3784290

Page

41-51

Document Type

Article

This document is currently not available here.

Share

COinS