SITE-SPECIFIC NUTRIENT MANAGEMENT (SSNM)
West Java, Indonesia
Team Leader
Dr. Sarlan Abdulrachman
Agronomist
Indonesian Institute for Rice Research
Sukamandi 41256, Subang
West Java
Email: sarlan@telkom.net
Partner Institution
Indonesian Institute for Rice Research (IIRR)
Site Characteristics
West Java is one of the most important rice-growing areas of Indonesia, which represents a region with early adoption of intensified production due to Green Revolution technologies. The annual irrigated rice harvest area is currently about 2 million ha with an annual production of about 10 million tons. Two to three rice crops are grown every year, mostly transplanted.
The two main rice-growing seasons are:
The average annual rainfall is about 1400 – 1800 mm, which occurs mostly from November through May and peaks from January to March.
Development and Evaluation of SSNM
Research on the development of SSNM was conducted in pilot villages from 1997 to 2000 in three pilot villages in Subang District near IIRR. From 2001 to 2004, activities were conducted in Bojong Jaya and Sukamandi in Subang District, primarily for fine-tuning the N recommendation. Nutrient omission plots were also conducted in Kuningan District in the 2003 dry season.
Research Results
Attainable yields and nutrient deficits (2001-03)
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 villages in 2003. 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 <0.5 t ha−1 for P and K in the dry season in Kuningan.
Table 1. Rice yields obtained with the nutrient omission plot technique in farmers’ fields in Sukamandi and Bojong Jaya, 2001-03.
|
Location and Parameter |
Dry season (n=30) |
|
Wet season (n=20) |
||
|
|
Mean |
SD |
|
Mean |
SD |
|
Sukamandi |
|
|
|
|
|
|
Attainable yield target; yield with NPK (t ha−1) |
7.0 |
0.4 |
|
7.3 |
0.6 |
|
N-limited yield; yield without fertilizer N (t ha−1) |
4.0 |
0.4 |
|
4.4 |
0.4 |
|
Yield response to N (t ha−1) |
3.1 |
0.5 |
|
2.9 |
0.7 |
|
Bojong Jaya |
|
|
|
|
|
|
Attainable yield target; yield with NPK (t ha−1) |
7.5 |
1.5 |
|
5.8 |
1.0 |
|
N-limited yield; yield without fertilizer N (t ha−1) |
4.6 |
1.3 |
|
3.3 |
0.7 |
|
Yield response to N (t ha−1) |
2.8 |
0.8 |
|
2.5 |
0.9 |
SD = standard deviation; n = number of replicated plots.
Table 2. Rice yields obtained with the nutrient omission plot technique in farmers’ fields in Kuningan district, dry season 2003. Values shown are means and standard deviations (SD) of 5 replicates.
|
Parameter |
Mean |
SD |
|
Attainable yield target; yield with NPK (t ha−1) |
8.6 |
0.7 |
|
N-limited yield; yield without fertilizer N (t ha−1) |
4.4 |
1.2 |
|
P-limited yield; yield without fertilizer P (t ha−1) |
8.3 |
1.0 |
|
K-limited yield; yield without fertilizer K (t ha−1) |
8.3 |
0.7 |
|
Yield response to N (t ha−1) |
4.2 |
1.3 |
|
Yield response to P (t ha−1) |
0.3 |
0.4 |
|
Yield response to K (t ha−1) |
0.2 |
0.2 |
SSNM-based nutrient requirements
The SSNM approach was used to estimate fertilizer N, P2O5, and K2O requirements based on the results in Tables 1 and 2. Total fertilizer N required for rice (Table 3) was estimated from the measured response to N (Tables 1 and 2) and an assumed target agronomic efficiency of N (kg yield increase/kg fertilizer N) of 25 for both the dry and wet seasons. 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 2) using the nutrient decision support system (NuDSS). Straw input was estimated as 2 t ha−1.
Table 3. Fertilizer N, P2O5, and K2O requirements estimated from results with the nutrient omission plot technique in West Java, Indonesia, 2001-03.
|
Location and Parameter |
Dry season |
|
Wet season |
||
|
|
Mean |
SD |
|
Mean |
SD |
|
Bojong Jaya |
|
|
|
|
|
|
Total fertilizer N required (kg ha−1) |
114 |
34 |
|
102 |
35 |
|
Sukamandi |
|
|
|
|
|
|
Total fertilizer N required (kg ha−1) |
122 |
22 |
|
116 |
27 |
|
Kuningan |
|
|
|
|
|
|
Total fertilizer N required (kg ha−1) |
167 |
54 |
|
|
|
|
Total fertilizer P2O5 required (kg ha−1) |
39 |
3 |
|
|
|
|
Total fertilizer K2O required (kg ha−1) |
81 |
11 |
|
|
|
SD = standard deviation
Locally Adapted Recommendation
Results from the nutrient omission plot technique and interviews with farmers—through interaction with local scientists—were used to formulate locally adapted recommendations for managing N, P, and K. These recommendations provide two complementary options for managing N with the LCC.
§ ‘Real-time’ N management: Farmers monitor the rice leaf color at regular intervals of about 7 to 10 days and then apply fertilizer N whenever the leaves become more yellowish-green than the critical threshold value indicated on the LCC.
§ ‘Fixed-time/adjustable dose’ N management: The time for N fertilization is preset at critical growth stages, and farmers adjust the dose of N upward or downward based on the leaf color.
The two options differ in frequency of visiting the field and measuring leaf color, but they are equally effective if properly implemented. The selection of the option can be based on farmer preferences and location-specific factors, such as frequency of visits by farmers to their fields and farmers’ knowledge of critical growth stages for N application. The fixed-time/adjustable-dose option is less time consuming. The real-time option requires less understanding of the critical growth stages for optimal timing of fertilizer N.
Locally adapted SSNM recommendations with the two options for N management are available for transplanted rice at the links below.
SSNM recommendation for transplanted rice: Real-time N management
Version 1 [PDF 146kb ]
SSNM recommendation for transplanted rice: Fixed-time N management
Version 1 [PDF 151kb]
West Java, Indonesia, SSNM version 1.0 (www.irri.org/irrc/ssnm)
Site Specific Nutrient Management