Forage quality, water use and nitrogen utilization efficiencies of pearl millet (Pennisetum americanum L.) grown under different soil moisture and nitrogen levels

The increasing scarcity of water for irrigation is becoming the most important problem for producing forage in all arid and semi-arid regions. Pearl millet is a key crop in these regions which needs relatively less water than other crops. In this research, a field study was conducted to identify the best combination of irrigation and nitrogen (N) management to achieve acceptable pearl millet forage both in quantity and quality aspects. Pearl millet was subjected to four irrigation treatments with interaction of N fertilizer (0, 75, 150 and 225 kg ha−1). The irrigation treatments were 40%, 60%, 80% and 100% of total available soil water (I40, I60, I80 and I100, respectively). The results showed that increasing moisture stress (from I40 to I100) resulted in progressively less total dry matter (TDM), leaf area index (LAI), and nitrogen utilization efficiency (NUzE), while water use efficiency (WUE) and the percentage of crude protein (CP%) increased. The highest TDM and LAI were found to be 21.45 t ha−1 and 8.65, in I40 treatment, respectively. TDM, WUE, CP% and profit responses to N rates were positive. The maximum WUE of 4.19 kg DM/m3 was achieved at I100 with 150 kg N ha−1. The results of this research indicate that the maximum profit of forage production was obtained in plots which were fully irrigated (I40) and received 225 kg N ha−1. However, in the situation which water is often limited and not available, application of 150 kg N ha−1 can produce high forage quality and guaranty acceptable benefits for farmers.

► Water stress and no nitrogen application caused a reduction in millet dry matter.
► By saving water in stressed conditions, water use efficiency increased.
► As drought stress increased, total digestible nutrient percentage decreased.
► N uptake decreased as more severe water stress was imposed.
► More soil water depletion reduced revenue and profit.