Resource Use Efficiencies of C3 and C4 Cereals under Split Nitrogen Regimes

Resources are limited, thus improving resource use efficiency is a key objective for cereal-based cropping systems. This field study was carried out to quantify resource use efficiencies in selected C-3 and C-4 cereals under split nitrogen (N) application regimes. The study included the following treatments: six cereals (three C-3: wheat, oat, and barley; and three C-4: maize, millet, and sorghum) and four split N application regimes (NS1 = full amount of N at sowing; NS2 = half N at sowing + half N at first irrigation; NS3 = 1/3 N at sowing + 1/3 N at first irrigation + 1/3 N at second irrigation; NS4 = 1/4 N at sowing + 1/4 N at first irrigation + 1/4 N at second irrigation + 1/4 N at third irrigation). Results revealed that C-4 cereals out-yielded C-3 cereals in terms of biomass production, grain yield, and resource use efficiencies (i.e., radiation use efficiency (RUE) and nitrogen use efficiency (NUE)), while splitting N into three applications proved to be a better strategy for all of the selected winter and summer cereals. The results suggest that C-4 cereals should be added into existing cereal-based cropping systems and N application done in three installments to boost productivity and higher resource use efficiency to ensure food security for the burgeoning population.