Forage Corn Response to Several Trickle Irrigation and Fertilization Regimes

The main technical advantages of trickle irrigation are better water and nutrient control (frequent supply as needed by the plant) and less outside disturbance that may cause lower water and nutrient use efficiencies (wind, loss of pressure in irrigation pipes). The purpose of this investigation was to determine the yield level of forage corn (Zea mays L.), cv. Newe Ya'ar 170 at a density of 110,000 plants per hectare, and its nutrient and moisture uptake as affected by the application of different amounts of irrigation water when plant nutrients in the soil were sufficient for maximum growth. Crop water requirement (WR) was based on estimates of ET/Eo (ET = crop evapotranspiration and Eo = Class A pan evaporation) multiplied by Em (measured Class A pan evaporation). In order to derive the different irrigation treatments, WR was multiplied by a variable K, i.e., 1.5, 1.0, or 0.5, giving the total amounts of water applied by trickles of 693, 459, or 230 mm, respectively over an experimental period of approximately 100 days. The averages of daily water tension in several soil profiles, daily dry matter production rates, cumulative dry matter yield, and daily nutrient (N,P,K) uptake by the plant were measured. It was found that the ratio between dry matter yield and ET/Eo was approximately 290 kg ha⁻¹day⁻¹ for all treatments. This value is high in comparison with those reported in the literature. The response curve of dry matter yield vs. evapotranspiration began near the origin and was linear. The maximum dry matter yield, 32,440 kg/ha, was obtained with an average soil water tension of 4 centibars at 0 to 150 cm soil depth and average NO₃−N concentration of about 80 ppm in soil solution to a depth of 30 cm during the period of most active N uptake. Average P and K concentrations in the upper 30 cm of soil at that time were 20 and 80 ppm, respectively. The maximum rate of dry matter production was 660 kg ha⁻¹day⁻¹ at the time of grain filling. As expected, irrigation with trickles allowed efficient control of the fertilizer-water-soil system, maintaining high water and nutrient availability to the crop.