SITE-SPECIFIC NUTRIENT MANAGEMENT (SSNM)
Team Leader
Jianchang Yang
Professor
College of Agriculture, Yangzhou University
Yangzhou, 225009
Jiangsu Province
Email: jcyang@yzu.edu.cn
Partner Institution
Yangzhou University
Site Characteristics
Jiangsu Province is located at the central part of the eastern coast of China. It covers a total area of 102,600 km2. Rice is grown once a year, from May to October, in rotation with wheat or oilseed rape. Most rice production in Jiangsu involves manual transplanting of Japonica cultivars. Labor-saving crop establishment techniques of mechanical transplanting, seedling throwing, and direct wet-seeding are increasing in importance. In 2006, about 15% of the rice production used seedling throwing, and about 10% used mechanical transplanting for establishment of Japonica cultivars. About 10% of the rice production used direct wet-seeding for establishment of Japonica cultivars.
The climate is subtropical with warm temperatures and an annual precipitation of 800–1200 mm. Rice soils in Jiangsu include clay loam soils near Wuxi in the south, sandy loam soils near Yangzhou in the middle, and saline-clay soils in the north near Lianyungang.
Development and Evaluation of SSNM
On-farm trials were conducted in 2003-05 to evaluate N management options and determine nutrient-limited yields through the nutrient omission plot technique. The evaluation of N management options was initially conducted using the chlorophyll (SPAD) meter. Beginning in 2004, the four-panel IRRI leaf color chart (LCC) was included in the development of improved N management practices.
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 averaged for three locations across 3 years from 2003-05. 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 0.8–1.2 t ha−1 for P and 2 t ha−1 for K.
Table 1. Rice yields obtained with the nutrient omission plot technique in farmers’ fields with single-rice crop in Jiangsu, averaged for 3 years from 2003-05.
|
Parameter |
Wuxi (n = 12) |
Yangzhou (n = 12) |
Lianyungang (n = 12) |
|||
|
|
Mean |
SD |
Mean |
SD |
Mean |
SD |
|
Attainable yield target; yield with NPK (t ha−1) |
8.7 |
0.2 |
8.5 |
0.4 |
9.1 |
0.3 |
|
N-limited yield; yield without fertilizer N (t ha−1) |
5.9 |
0.2 |
5.7 |
0.3 |
5.8 |
0.3 |
|
P-limited yield; yield without fertilizer P (t ha−1) |
7.8 |
0.2 |
7.5 |
0.4 |
7.8 |
0.4 |
|
K-limited yield; yield without fertilizer K (t ha−1) |
6.8 |
0.3 |
6.5 |
0.4 |
7.0 |
0.4 |
|
Yield response to N (t ha−1) |
2.7 |
0.3 |
2.8 |
0.5 |
3.3 |
0.4 |
|
Yield response to P (t ha−1) |
0.8 |
0.2 |
1.0 |
0.1 |
1.2 |
0.2 |
|
Yield response to K (t ha−1) |
1.9 |
0.2 |
2.0 |
0.2 |
2.0 |
0.2 |
SD = standard deviation; n = number of replicated plots.
SSNM-based nutrient requirements
The SSNM approach was used to estimate fertilizer N, P2O5, and K2O requirements based on the results in Table 1. Total fertilizer N required for rice (Table 2) was estimated from the measured response to N (Table 1) and an assumed target agronomic efficiency of N (kg yield increase kg fertilizer N−1) of 18. See N management for more details.
Total fertilizer P2O5 and K2O were estimated from attainable yield target, P-limited yield, and K-limited yield (Table 1) using the nutrient decision support system (NuDSS) software. (NuDSS). Straw input was estimated as 3 t ha−1.
Table 2. Fertilizer N, P2O5, and K2O requirements for single rice estimated from results with the nutrient omission plot technique in Jiangsu, China, 2003 to 2005.
|
Location and parameter |
Single rice (Japonica) |
|
|
|
Mean |
SD |
|
Wuxi |
|
|
|
Total fertilizer N required (kg ha−1) |
182 |
17 |
|
Total fertilizer P2O5 required (kg ha−1) |
41 |
2 |
|
Total fertilizer K2O required (kg ha−1) |
95 |
6 |
|
Yangzhou |
|
|
|
Total fertilizer N required (kg ha−1) |
185 |
31 |
|
Total fertilizer P2O5 required (kg ha−1) |
40 |
2 |
|
Total fertilizer K2O required (kg ha−1) |
94 |
7 |
|
Lianyungang |
|
|
|
Total fertilizer N required (kg ha−1) |
220 |
25 |
|
Total fertilizer P2O5 required (kg ha−1) |
44 |
2 |
|
Total fertilizer K2O required (kg ha−1) |
102 |
5 |
SD = standard deviation
Locally Adapted Recommendation
Results from the nutrient omission plot trials and evaluation of N management options were used to formulate locally adapted recommendations for managing N, P, and K. A recommendation for transplanted single rice is available at the links below.
SSNM recommendation for transplanted single rice (Japonica)
Version 2.0 [PDF 161kb]
SSNM recommendation for seedling throwing and mechanical transplanted single rice (Japonica)
Version 1.0 [PDF 163kb]
SSNM recommendation for wet-seeded single rice (Japonica)
Version 1.0 [PDF 162kb]
Jiangsu, China SSNM version 2.0 (www.irri.org/irrc/ssnm)
Site Specific Nutrient Management