Table 4.
Estimated P and K balances—based on nutrient inputs from fertilizer, crop residues, and irrigation water—for field-specific nutrient management through Nutrient Manager for Rice (NMR), a uniform fertilizer application using the blanket fertilizer recommendation (BFR), and farmer’s fertilizer practice (FFP) in three rice-growing seasons in Tamil Nadu, India
| Treatment | Estimated P balance (kg P ha−1) | Estimated K balance (kg K ha−1) | ||||
|---|---|---|---|---|---|---|
| Kuruvai | Samba | Thaladi | Kuruvai | Samba | Thaladi | |
| NMR | 0 (1.4) | 1 (2.0) | 5 (2.2) | − 28 (11.1) | − 24 (13.1) | 26 (14.1) |
| BFR | 9 (1.2) | 8 (2.5) | 14 (1.8) | − 5 (6.9) | − 28 (14.4) | 36 (15.9) |
| FFP | 9 (7.0) | 8 (10.8) | 15 (7.3) | 5 (18.7) | − 7 (32.2) | 41 (25.5) |
| NMR target | 0 (0.3) | 0 (0.2) | 0 (0.2) | − 30 (7.0) | − 33 (5.5) | − 4 (6.8) |
Values in parenthesis are standard deviations
Nutrient balances assume K input from irrigation water of 25 kg ha−1 in kuruvai, 8 kg ha−1 in samba, and 4 kg ha−1 in thaladi; no input of P from irrigation water; no input of P and K from organic materials other than rice residue; and no output of P and K by processes other than crop removal