Fertilizer use efficiency

Abstract

The combined effects of improved hybrids, better water management, increased nutrient application rates, and higher plant populations have significantly increased maize (Zea mays L.) dry matter, grain yield, and nutrient accumulation when compared to benchmark data collected by Sayre in 1940 and Hanway in 1959. To evaluate the effects of those changes in management practices on seasonal rates of accumulation, aerial dry matter, N, P and K accumulation data from the benchmark studies, 2 recent field studies and a 1985 maximum economic yield (MEY) study were described with compound cubic polynomials. The equations were differentiated to determine rates and plotted as a function of growing degree units. Aerial accumulation patterns were similar for all 5 studies even though grain yields averaged 6.4 and 7.1 Mg ha^‐1 in the benchmark studies, 9.7 and 14.0 Mg ha^‐1 in recent studies, and 19.3 Mg ha^‐1 in the MEY study. Peak daily N, P and K accumulation rates during vegetative growth were 3, 2, and 6 times higher with intensive management than in benchmark studies. During grain‐fill, peak accumulation rates were doubled for N and P, but unchanged for K. Rate curves for all 5 data sets showed distinct peaks during both vegetative and reproduction growth stages. Double peaks suggest that for maximum maize yield a minimum stress environment must be provided during both vegetative and reproductive growth stages. These results can be used to project optimum management strategies for profitable maize production.

Key words:

• Zea mays L.
• maximum economic yield
• N
• P
• K