Comparative analyses of variable and fixed rate irrigation and nitrogen management for maize in different soil types: Part II. Growth, grain yield, evapotranspiration, production functions and water productivity

Comparisons of variable rate irrigation (VRI) and fertigation (VRF) with fixed (FRI), no (NI) conventional fertilizer management for maize (Zea mays L.) under three soil types (S1, S2 S3) were made years (2015, 2016 2017). The research quantified compared growth development [leaf area index (LAI) plant height], grain yield, crop evapotranspiration (ETc), irrigation-yield production functions (IYPF), evapotranspiration-yield (ETYPF) water productivity (CWP) VRI, FRI NI at (FRF), VRF pre-plant nitrogen (PP) in the same environment agroomic practices. treatment used 20% less as compred PP FRF without significantly (P > 0.05) reducing yield. In higher elevation S1, yield was not different between VRI treatments. However, S3 which have lower elevation, 43% 55% greater than respectively. On average, total amount 24% only 4% reduction FRI. Soil type impacted response to ETc responses also varied VRI. For all years, observed treatment, except 2015 S1 where highest had per unit Observing linear relationship pooled data each type, a 25.4 mm (beyond intercept) resulted 0.48 0.35 ton ha−1 respectively, S1; 0.75 0.45 S2; 0.71 0.43 S3. strategy increased variability CWP management. lowest coefficient variation (CV) ranged from 8% S1-FRI high 35.3% impact on CWP. three-year average basis, 2% whereas 11% Stronger (IYPF ETYPF) levels. results this indicated that, most cases, superior performance terms maintaining optimum variations based status has potential improving certain conditions or such S1. further is needed validate/justify its adoption fields significant spatial heterogeneity (both horizontal vertical domains) understand economics VRI-VRF systems. These would be beneficial growers their advisors understanding strategies VRF, application.