Efficiency Test of IRRI Fertilizing Recommendations on Rainfed Low Land Rice Field in West Kalimantan

Fertilizing recommendation for lowland rice field in West Kalimantan is still in national scale and tends to be excessive. It is less relevant due to various factors such as the test method competence, the carrying capacity  of  the  land,  and  the  diverse  condition  of  rice  field  agro-ecosystem.  Site-specific  nutrient management (SSNM) is an approach for rice fertilizing on paddy plot based on science, history of land fertilization,  and  nutrient  sources  surrounding  the  area  which  can  affect  soil  fertility  level  and  soil conservation.This study was aimed to examine fertilizing efficiency of N, P, and K and the increased productivity of rice by utilizing software (website) of the IRRI. The study was conducted in farmers fields in two villages, i.e. Anjongan and Pak Bulu, Pontianak Regency, West Kalimantan. The results showed that the SSNM fertilization on rice increased yields by the average of 0.62 t ha-1 (13.47%) per growing season. The efficiency of SSNM fertilization was on the average of 22.05% N, 48.25% P2O5, and 31.50% K2O. The additional profits obtained from the SSNM recommendation was on the average of IDR 1,886,317 per ha pergrowing season compared to the profits from the FFP (farmer fertilizer practice).Keywords: Fertilizing efficiency, low land, rice, site specific fertilization [How to Cite: Muhammad H, M Syam and DP Widiastuti. 2014. Efficiency Test of IRRI Fertilizing Recommendations on Rainfed Low Land Rice Field in West Kalimantan. J Trop Soils 19: 25-33. Doi: 10.5400/jts.2014.19.1.25]  [Permalink/DOI: www.dx.doi.org/10.5400/jts.2014.19.1.25] 


INTRODUCTION
Determination of rice fertilizer dosage recommendations at the national level is considered to be no longer relevant as guidelines for fertilizing rice fields in several regions in Indonesia (Adnyana. 2011). The diversity of soil fertility conditions and site specific environment in some areas, causing the need for balanced fertilization based on site specific conditions and the fertilizer recommendation given is not to be the same in every region (Suryana 2004;Haefele et al. 2010).In some areas of intensification, frequent fertilization lead to the imbalance of nutrients in the soil, damaged to soil properties, environmental pollution and lost of farmer profits (Xu et al. 2009;Pampolino et al. 2012). Excessive fertilization which was not appropriate in dosage, time, and way could cause the plants grow unoptimally, either because of nutrient deficiencies or excessive fertilization (Dobermann and Fairhurst 2000;Buckley and Carney 2013).
Recommended dose of fertilizer for rice is influenced by various factors such as the kind of the test method, the carrying capacity of the land, and the crop needs on various nutrients (Setyorini et al. 2006). There have been many test methods to determine the efficiency of rice fertilization, such as the use of leaf color chart in rice that can save N fertilizer (Wahid 2003). The site specific nutrient management (SSNM) fertilization is a soil nutrient balance-based fertilization technology which uses a rational, efficient fertilization based on the plant needs and according to their variation in time and space (Dobermann 2003;Dobermann et al. 2004;Pasuquin et al. 2014). The SSNM is a computer-based guidelines developed by the International Rice Research Institute (IRRI) in collaboration with the Agency for Agricultural Research and Development (IAARD) through the institutions under its aegis such as the Assessment Institute for Agricultural Technology (AIAT) in every province in Indonesia.
nutrients and local way in order to be easily applied by extension workers and farmers, and then to be developed on local land conditions and rice crops (local specific) (Fageria and Virupax 1999;Timsina et al. 2010).
Farmers, agricultural extension workers, and researchers are involved in the efficiency test of fertilization, in which the determination and implementation of the recommendations are conducted through group discussions. Farmers in the selected fields can work altogether on the work plan that has been agreed. With this efficiency test of fertilization, the recommended fertilizer based on the SSNM principles of IRRI can be analyzed with agronomic perspective. The purpose of this study was to test the fertilization efficiency of rice based on the SSNM recommendation of IRRI and then compared to the practices and habits of FFP in West Kalimantan.

MATERIALS AND METHODS
Efficiency test of the SSNM fertilization was conducted on rainfed land owned by farmers in two villages, i.e. AnjonganVillage and Pak Bulu Village, Anjongan Sub-district, Pontianak Regency, West Kalimantan Province. This study was carried out in May to December 2012.
Material used in this study were rice seed, fertilizers, i.e. urea, KCl, and NPK compound fertilizers and pesticides, stationery, and gauges crops. Fertilization recommendations were based on the principles of SSNM compared to the FFP recommendations on the same land conditions. This field test was conducted by involving farmers in which the determination and implementation of the recommendations through discussions with farmer groups, extension workers, and researchers from the AIAT.
The study was conducted in rainfed land owned by farmers in the two villages involving 40 farmers which have the land area of 300 m 2 to 1000 m 2 . The determination of SSNM fertilizer dose was based on the fertilizer dose recommendation of IRRI, which was conducted by interviewing each selected farmer to fill the questionnaire from IRRI website (http://webapps.irri.org/nm/id). Based on the results of SSNM fertilizer recommendations through that internet access, the fertilization period was applied in three times, i.e. in the early period (0-14 days after planting), active tillering, and at the time of primordia (panicle initiation) ( Table 1). While the dose of fertilizer by FFP was applied in two periods of fertilization (Table 2).
Each farmer managed both two study plots (SSNM and FFP plots) uniformly.Tillage, rice The SSNM is a fertilization technology with a method that requires an answer to a question by using the internet applications that can be accessed through http://webapps.irri.org/nm/id. At the same time, approaches must be relatively simple with minimal characterization or interviewing of farmers for each field in order to ensure rapid, cost effective delivery of field-specific guidelines to millions of small-scale farmers ). The answers on some questions that can be easily understood by farmers, such as rice field specifications and history of rice farming management practiced by the farmers which start from land preparation, use of inputs such as seed and fertilizer to harvesting and post-harvest handling, then calculated and can be made rice fertilization recommendation on site specific (Witt and De Datta 1989;Mutert and Fairhurst 2002;Fairhurst et al. 2007). Therefore, the presentation of the SSNM principles needs to be simplified and adjusted with the local way in order to be easily applied by extension workers and farmers and then to be developed on local land condition and rice crop (Janssen et al. 1990).
This SSNM technology needs to be tested in every area in accordance with the nature and diversity of rice fields characteristics and rice farmers characteristics in each region in Indonesia, including in Pontianak Regency, West Kalimantan Province. Pontianak Regency is one of the rice production centers in West Kalimantan, especially in Anjongan Sub-district. Most of the rice fields in Pontianak Regency are in rainfed areas in which the irrigation sources depend on rainfall and in some locations the irrigation sources come from the mountain. The rice yields in those areas were still relatively low in the average of 2-3 tons per hectare.
The farmers habits in those region are transplanting with more than 20 days seedlings, burning rice straw and not returning the residue of the harvested rice straw to the rice fields, applying simple fertilizer based on the ability of farmers to buy fertilizer. Yet for the developed farmers, fertilization rates are in a high dose such as, for urea ranges from 300-400 kg ha -1 . This is wasteful and can cause soil contamination problems if it is done continuously. The SSNM is conducted with a hope to be able to increase the fertilization efficiency, profitability and rice yields in rainfed lowland rice for average climatic conditions (Wang et al. 2007;Sapkota et al. 2014). The SSNM-based fertilizer efficiency test in the field can be used to evaluate the fertilizer recommendation for rice fields in various rice producing areas in Indonesia. The SSNM scientific principles for optimally supplying crops with varieties, planting, fertilization, pest and disease control, harvesting and post-harvest handling were treated in the same way for both plots (SSNM and FFP). Fertilizers used for SSNM and FFP were bought from the same source.
Determination of crop yieldswas made when the rice crop physiologically mature. All clumps in the sample plot size of 2 x 5 m were harvested in three plots from the two plot treatments (SSNM and FFP). Then, the weight of dry grain harvest of the SSNM and FFP treatments were measured in kg. Then each dry grain yields were determined at 14% moisture content, calculated by correcting the dry grain yields of SSNM and FFP plots at 14%    moisture content. The yields were converted in t ha -1 . Data analysis of rice yields from the SSNM fertilization was compared to the FFP, so it could be seen how much the efficiency of fertilization based on SSNM.

RESULTS AND DISCUSSION
Fertilization is an effort to increase the availability of nutrients in order to meet the needs of plants. SSNM in aimed at dynamic field-specific management of N, P, and K fertilizer to optimize the balance between supply and demand of nutrients. The plant needs for N, P, or K fertilizer are determined from the gap between the supplies of a nutrient from indigenous sources (Wang et al. 2007). Derived from SSNM fertilizer recommendations calculation, the fertilization period was applied in three times with the highest dose of N, P and K were 146, 60 and 60 kg ha -1 respectively (Table 1). At the same time, as the dose of fertilizer by FFP gave in two periods of fertilization with the highest dose of N, P and K were 214, 110 and 60 kg ha -1 ( Table 2).
It is quite likely that applying fertilizer N at rates and times to better match the dynamic needs of the rice plant, as practiced with SSNM, can lead to reduced losses of fertilizer N as gases including N 2 O . Fertilizer N applied to submerged rice soils is prone to large losses through mechanisms as ammonia volatilization and nitrification-denitrification (Buresh et al. 2006). Nitrous oxide, a greenhouse gas, is one of the end products of nitrification-denitrification. More effective nutrient management through SSNM can enhance the fertilizer use efficiency leading to more grain yield per unit of fertilizer. This can avoid accumulation of inorganic nutrient in periods when crop demand for added nutrient is low, such as at the end of the rice-growing season.

Grain Yields
Dry grain yields of 14% moisture content from 40 farmers in which each farmer fertilizes on plot based on SSNM and FFP in AnjonganVillage and Pak Bulu Village are shown in Figure 1. Figure 1 showed that the fertilization recommendation from IRRI (SSNM) in Anjongan and Pak Bulu Villages had greater dry grain yields (moisture content of 14%) than that of FFP fertilization. The average of dry grain yields (moisture content of 14%) on the SSNM fertilization treatment were 4.93 t ha -1 and 4.42 t ha -1 , for Anjongan and Pak Bulu respectively, whereas the FFP were only 4.36 t ha -1 and 3.75 t ha -1 (Figure 2). This showed that the fertilization treatment based on site specific nutrient fertilization (SSNM) was proven to have  the higher grain yields than the FFP. This agreed with the study of Li et al. (2012) who conducted a research in Jiangsu Province of China to incorporate SSNM into local rice management system in a wheat -rice rotation. They increased rice grain yield by 30% over local FFP, but saved only about 5% N fertilizer. In a more recent study also conducted in Jiangsu Province of China, Xue et al. (2013) developed an improved rice management system combining both SSNM and FFP. Compared with local FFP, SSNM increased rice yield and agronomic N use efficiency by 14.4% and 64.1%, respectively. Fertilization based on the SSNM recommendation with a lower dose and three periods of fertilization, i.e. in the early planting (0-14 days after planting), in the active tillering of rice plants, and at the time of primordia (panicle initiation), was able to produce more grain yields compared to the FFP fertilization which only applied two periods of fertilization, i.e. in the basis fertilization (basal) and at the time of primordia (panicle initiation).

Fertilization Efficiency
Results of fertilization efficiency on N, P 2 O 5 , and K 2 O on SSNM and FFP fertilization in AnjonganVillage and Pak Bulu Village can be seen in Table 3. Table 3 showed that there was N fertilizer efficiency both in AnjonganVillage and Pak Bulu 6 4 2 0 Added net benefit (Rp.000.000)  Figure 3. The average for efficiency of N, P 2 O 5 and K 2 O fertilization on the SSNM ( ) and the FFP ( ) in AnjonganVillage and Pak Bulu Village. Soils, Vol. 19, No. 1, 2014: 25-33 Village. The SSNM fertilization in those two locations could save N fertilizer at 15 kg ha -1 (11.6%) and 39 kg ha -1 (32.5%), respectively, when compared to FFP fertilization.This agrees with research done by Pasuquin et al. (2014)   China, SSNM increased N fertilizer efficiency more than 50% while fertilizer N was reduced by about 30% (Wang et al. 2007). Similarly, the efficiency of P 2 O 5 fertilizer was also at 44 kg ha -1 (58.7%) in Anjongan Village and 14 kg ha -1 (37.8%) in Pak Bulu Village. However, there was no savings on K 2 O fertilizer of the SSNM fertilization recommendations in AnjonganVillage. This was likely due to farmers habits who did not return the residue of harvested rice straw to the rice fields. The residue of harvested rice straw from grain threshing with a thresher was just stacked on the edge of rice fields and burned, so that the source of K was not utilized. Location of irrigation water sources which was far enough from rice fields and drought were also possible causes that made K 2 O fertilization on SSNM was higher than the FFP. It did not happen in the locations of Pak Bulu Village that the rice fields were close to irrigation sources and the residues of harvested rice straw were returned to the rice fields, so in that location it could save K 2 O fertilizer at 16 kg ha -1 (47.1%) (Figure 3).

Additional Net Profit
The additional net profits of the SSNM fertilization recommendation was to wards the FFP fertilization in Anjongan Village and Pak Bulu Village (Figure 4). Figure 4 showed that the additional net profit in Pak Bulu Village was higher than Anjongan Village. This was due the fact that the N, P 2 O 5 and K 2 O fertilizations in Pak Bulu Village were more efficient than in the AnjonganVillage (Table 3). The additional net profit of the SSNM fertilization recommendation towards the FFP fertilization for Anjongan Village was in the average of IDR. 1,556,277 and Pak Bulu Village was IDR 2,216,357 (Table 4).  reported that the added net annual benefit due to use of SSNM was 34 US$ ha -1 year -1 in Vietnam,106 US$ ha -1 year -1 in the Philippines, and 168 US$ ha -1 year -1 in India. The increased benefit with SSNM was attributed to increased yield rather than reduced costs of inputs.

CONCLUSIONS
Site-specific nutrient management (SSNM) fertilization based on the IRRI recommendation was able to increasing rice productivity by the average of additional increase of 0.62 t ha -1 (13.47%) per growing season. The SSNM fertilizer recommendation on rice plants was more efficient compared to the farmer's fertilization practice (FFP), saving N fertilizer in the average of 2.7 t ha -1 (22.05%), P 2 O 5 of 2.9 t ha -1 (48.22%), and K 2 O of 0.9 t ha -1 (17.89%) per season. The additional net profits from the IRRI fertilization recommendation (SSNM) compared to the FFP in Anjongan Village was about of IDR 1,556,277 andin Pak Bulu Village was IDR 2,216,357. The additional net profit of the SSNM fertilization was about of IDR 1,886,317 per growing season in Pontianak Regency, West Kalimantan Province. It is expected that in each of the Agricultural Extension Center and all farmers in West Kalimantan Province, especially in Pontianak Regency, can refer to the IRRI fertilization recommendation based on the SSNM, because it was proven to be more efficient and profitable. However, it still needs to be furthered research on the SSNM fertilization recommendation in tidal lands.