Site Specific Nutrient Management

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Heilongjiang, China


		Research Results

Attainable yields and nutrient deficits

The nutrient omission plot technique was used to determine attainable yield with full fertilization and nutrient-limited yields. Table 1 shows the results in 2004-05. Rice grain yield in plots fully fertilized with N, P, and K provided an estimate of the attainable yield target. The yield of rice not fertilized with N, but fertilized with other nutrients was used to determine N-limited yield. Similarly, the yield of rice not fertilized with P, but receiving other nutrients indicated P-limited yield; and the yield of rice not fertilized with K, but receiving other nutrients indicated K-limited yield. The difference between the yield target and a nutrient-limited yield indicated the crop response to the nutrient. This response averaged 0.6 t ha⁻¹ for P and 1 t ha⁻¹ for K.

Table 1. Rice yields obtained with the nutrient omission plot technique in farmers’ field near Harbin in 2004-05.

Parameter	Single rice (n=6 of N and 2 for P and K)
	Mean	SD
Attainable yield target; yield with NPK (t ha⁻¹)	8.6	0.4
N-limited yield; yield without fertilizer N (t ha⁻¹)	6.2	0.8
Yield response to N (t ha⁻¹)	2.4	0.8
P-limited yield; yield without fertilizer P (t ha⁻¹)	8.3	0.2
K-limited yield; yield without fertilizer K (t ha⁻¹)	7.9	0.2
Yield response to N (t ha⁻¹)	2.4	0.8
Yield response to P (t ha⁻¹)	0.6	0.4
Yield response to K (t ha⁻¹)	1.0	0.4

SD = standard deviation; n = number of replicated plots.