Increase Rice Yield with Site-Specific Nutrient Management Technique
Proper crop nutrition is essential in ensuring a high yield. But since soil condition varies from one farmland to another, approach on nutrient management should be based on location, crop needs, and season.
This is the principle behind the SiteSpecific Nutrient Management (SSNM) technique, which is also known as SiteSpecific Crop Management. It’s effective. In fact, the Irrigated Rice Research Consortium noted in the initial regional evaluation of SSNM in six Asian countries that on the average, yields and gross return increased by 7 percent from 1997 to 2000. Here in the Philippines, yields range from 5 tons to 9 tons per hectare.
Moreover, PhilRice consultant Hermenigildo Gines described SSNM in his paper “The Principles of Site-Specific Nutrient Management for Rice in the Philippines,” as a technique that advocates the “optimal use of existing indigenous nutrient sources like crop residues and manures.” He adds that by “timely application of fertilizers to meet the deficit between rice demand for nutrients and the supply of nutrients from the soil and organic inputs”, farmers can expect higher yields from their farms.
TECHNIQUES IN IDENTIFYING NEEDED NUTRIENTS
SSNM seems complicated but it is actually simple. Farmers just have to identify the needed nutrients, set a target yield, and fertilize the soil with the nutrients it lacks.
The indigenous nutrients from the soil and water, including manures, remains of crop and grasses, and biological nitro gen-fixation are among the most important considerations in making the recommendation and setting a target yield for SSNM. “Thus, these must be determined first,” Gines advised.
In SSNM, nutrient omission plot technique (NOPT) is done to know the natural capacity of the soil, water, and other sources mentioned above to provide the right nutrients for the rice plant. To do the NOPT, three plots should be established in the field. The whole field should be fertilized with complete fertilizer, which is composed of nitrogen, phosphorus, and potassium or NPK, while the plots should receive only two nutrients each. Minus-N plot should receive P and K to determine the indigenous N supply. Minus-P plot, on the other hand, should have N and K to determine the P supply, while Minus-K plot should receive N and P to determine the K supply (see the table of fertilizer recommendation per yield target per season on next page).
The leaf color chart (LCC) can be used also “to determine the N requirements of the plant,” adds Gines. N fertilizer is only applied when the reading falls below a critical value.
However, the NOPT would take a season to complete. Hence, farmers may employ other soil analysis methods. These include minus-one element technique (MOET), soil test kit (STK), and laboratory analysis.
The MOET can be used before the growing period or at land preparation stage. It is done in a puddled soil, and results can be seen in 30-45 days. Thus, fertilizer recommendation can still be made when the crop has just been planted.
In the laboratory analysis, the soil is air dried, then pulverized before subjecting to analysis. However, release of nutrients from a paddy or flooded soil is different from a dry soil. Hence, the MOET is still the better alternative to assess nutrient deficiencies of the soil.
Analysis through STK, on the other hand, does not indicate the actual amount of nutrients in the soil but it can be used as a quick test on the sufficiency or deficiency of N, P, and K.
“From these options,” says PhilRice soil expert Wilfredo Collado, “we still consider the NOPT as the most efficient since it entails all stages of the crops in a season-long basis.” On the other hand, “whichever of these techniques is used, yield [will still be] higher.”
Fertilizer recommendation (bag per hectare) per yield target season (solophos as source of P)
Soil Nutrient Status Wet Season Yield Target (5 t/ha) Dry Season Yield Target (7 t/ha)
P and K are not deficient First application: First application:
4 bags 14-14-14-12S 6 bags 14-14-14-12S
P and K are deficient If soil is clay: If soil is clay
First application: First application:
4 bags 14-14-14-125 + 0.5 bag 16- 5 bags 14-14-14-12S + 2 bags 16-
20-0 + 0.5 bag 0-0-60 20-0 + 1 bag 0-0-60
If grain yield is either If soil is sandy: If soil is sandy:
IPS or IKS plots is 4 t/ha First application: First application:
4 bags 14-1-4-14-12S + 0.5 bag 5 bags 14-14-14-12S + 2 bags 16-
16-20-0 20-0
At EPI: At EPI:
0.5 bag 0-0-60 1 bag 0-0-60
Only P is deficient First application: First application:
4 bags 14-1-4-14-12S + 0.5 bag 5 bags 14-14-14-12S + 2 bags 16-
16-20-0 20-0
Only K is deficient If soil is clay: If soil is clay:
First application: First application:
4 bags 14-14-14-12S + 0.5 6 bags 14-14-14-125 1 bag 0-0-60
bag 0-0-60
If soil is sandy: If soil is sandy:
First application: First application:
4 bags 14-14-14-12S 6 bags 14-14-14-12S
At EPI: At EPI:
0.5 bag 0-0-60 1 bag 0-0-60
ANOTHER OPTION
In case the LCC is not available, farmers may refer to the critical growth stage timeline to know when they should apply fertilizer.
The timeline identifies one stage when fertilizer application is optional and three stages when it is necessary. The first stage is at early growth stage (10-14 days after transplanting or DAT), then during active tillering (23-33 DAT), and panicle initiation (33-44 DAT) for early maturing varieties.
SETTING A TARGET YIELD
Once the needed nutrients and the amount of fertilizer to be applied have been identified, setting a target yield follows.
In doing so, farmers should foremost consider the soil condition, planting season, climatic situation, pest occurrence, and variety to be used. Farming history and should be taken into account as well.
Financial capability is very crucial. Certain amounts of fertilizer should be applied to meet the target yield. So if the farmer opts to achieve the maximum yield, he must have enough money to
buy all the fertilizers needed. Otherwise, he should settle on the yield option that he affords.
The minimum yield that can be derived from SSNM is 5 tons per hectare and this, says Collado, is way higher than the yields farmers usually have. He is also certain that employing the SSNM ensures higher productivity even at a minimum yield target if farmers will follow the management practices specifically recommended for their respective field conditions.
SUCCESS STORIES
By employing SSNM, Venencio Barayuga and Juanito Caraang both from Batac, Ilocos Norte had a yield of 4 tons from one-half hectare and 5 tons from 6,000-square meter farm, respectively.
Barayuga shares that he used to apply fertilizer during early stage and harvest only 50 cavans per hectare until he employed SSNM. “I realized that it is better than what [I used to practice] when [I had] 30 more bags last season,” he adds.
Caraang, on the other hand, has been using the LCC for three seasons now. He is very selective on which recommendations to follow. After attending series of trainings, he applied the technologies taught to him like the MOET and appropriate fertilizer application.
“I never thought I could [still] increase my yield. With proper choice of variety and crop management, I realized I could make more out of my meager farm area,” Caraang shares.
What’s more is that in 2006, a farmer in Llanera, Nueva Ecija obtained an average yield of 8.5 tons per hectare, while other farmers there got a yield of more than 7 tons per hectare.
Farmers in Agusan Del Norte have also increased their yields. One of them is Teodora Agsaway of Cabadbaran City. By applying the SSNM, she has reduced her expenses on fertilizer. “We have less input cost because we only apply fertilizer when it’s necessary, [and we determine when it's needed because of the SSNM].
From the yield target of less than 5 tons per hectare in 1998, Agusan Del Norte now aims to obtain a yield of 7 tons per hectare. Every province can achieve a yield this high or even higher if farmers will judiciously employ the SSNM and maximize their resources, says Collado.
