On- farm precision nutrient prescription under pre- dominant cereal- cereal systems using Nutrient Expert®

This study compared a Nutrient Expert® (NE)-based nutrient recommendation with the official state recommendation (SR) and farmers' fertilizer practice (FFP) in the rice-wheat cropping system across five locations of Amritsar, Modipuram, Kanpur, Faizabad, and Nainital. Ten on-farm sites were selected at each of the locations, and the three nutrient management options were evaluated for agronomic, economic and environmental benefits through yield, net returns, and nutrient use efficiency estimations. Soil pH was generally alkaline (>7.5) except in Nainital (pH 6.7), and electrical conductivity (EC) was within the safe limits (<0.4 dS/m), except in Modipuram (0.48). Organic C was low (<0.5%) in Amritsar, Kanpur, and Faizabad, while medium at Modipuram (0.57) and high at Nainital (0.77). All locations had low available nitrogen (N) (<280 kg/ha), medium to high available phosphorus (P) (12.5 to 32.5 kg/ha), and medium (135 to 335 kg/ha) available potassium (K).

The NE-based recommendations produced 5.2 to 7.1 t/ha of rice yield, with an average of 6.1 t/ha, which was 8 and 25% higher than SR and FFP, respectively. Similar observations were also reported in wheat where yield ranged from 3.5 to 5.0 t/ha, with an average of 4.4 t/ha, that was 8 and 16% higher than SR and FFP, respectively. The rice-equivalent yield (REY) of the rice-wheat system was 10.9, 10.0, and 9.0 t/ha for NE, SR, and FFP respectively. The average REY in the NE plots were 8 and 20% higher than SR and FFP, respectively. The higher yields of rice and wheat with NE was due to high nutrient uptake and high nutrient use efficiency. The average N (114 kg/ha), P (26 kg/ha), and K (122 kg/ha) uptake of rice in the NE plot was 11, 16, and 10% higher than SR, and 30, 58, and 38% higher than FFP, respectively. Similarly, partial factor productivity (PFP) of N, PFP-P and PFP-K in the NE treatment were 53, 391, and 128 kg/kg, respectively. The PFP-N in the NE treatment was 13 and 46% higher than SR and FFP, while PFP-P was higher than SR and FFP by 82 and 46%, respectively. The PFP-K for NE was 27 and 24%, less than SR and FFP, indicating that the NE tool helped suggest adequate rates of K, which was under-applied in the SR and FFP treatments. The added net return over FFP was Rs.18,710 for the NE treatment and Rs.15,100 for the SR treatment. The performance of the NE-based nutrient recommendations are currently being analyzed for other cropping systems such as rice-rice, rice-maize, and maize-wheat systems.