Paper Number 10

The movement from conventional agricultural practices to
integrated nutrient management in Thailand*

* This country report has not been formally edited and the designations and terminology used are those of the author.

Chawalit Hongprayoon
Department of Soil Science, Faculty of Agriculture, Kasetsart University,
Kamphaeng Saen Campus, Kamphaeng Saen Nakorn Pathom, Thailand

1. Introduction

In tropical soils, precipitation, temperature and soil aeration express a strong effect on the quantity of organic materials input and the rate of organic matter decomposition in soil. When virgin soil was transformed into farm land, soil organic matter tended to shift towards loss more than gain. After a long period of agricultural uses, soil organic matter decreased to very low level compared to the virgin soil. Raising the soil organic matter level to high productive level is very difficult since it requires integration of technologies and the strong intention of the farmers to improve their lands. Moving forward to agricultural sustainability, more strategies have to be integrated into the programme including strengthening the basic knowledge of the farmers, including the review of national policies to improve the quality of the agricultural resources.

In Thailand, major constraints to improve soil productivity include inappropriate soil organic matter management, unbalanced plant nutrient input and unsustained nutrient removal from soil, high cost of inputs and drought in rainfed areas. Thai national strategies are now moving towards improvement of agricultural resources such as “National Agenda on Organic Agriculture” strategy and alleviation of the drought problem with “Water Management Modernization” mega-project. The intensive nutrient managements for crop production such as site-specific nutrient management or precision agriculture are also studied in some economic crops. These agriculture management strategies are not yet widely adopted in the country but they will be the next step for the integrated nutrient management in Thailand.

2. General practices in relation to soil productivity

Even though the realization about proper management of agricultural resources was gradually increased, the mainstream agricultural practices in Thailand is still far from maintaining or enhancing the soil productivity. Yield of the main crops like rice, maize, and sugarcane are somewhat increased from the past. From 1995 to 2004, yield of rice increased slowly from 2.42 to 2.64 tonnes/ha, yield of maize increased from 3.29 to 3.87 tonnes/ha, but yield of sugarcane varied widely between 46.1 to 65.2 tonnes/ha which depends mostly on climatic condition. The causes of increasing yields were likely to come from high yield crop varieties or better management in irrigation rather than soil improvement methods. Increasing yield, on the other hand, means more nutrients were removed from soil if the nutrient input rate was not increased. Total yields of rice, maize, and sugarcane of the country were 58.189, 4.216, and 49.572 million tonnes in the year 2004, respectively. With the average nutrient content of the crops in Table 1, enormous nutrient loss from agricultural soil in one year from only three crops can be estimated. Converting the nutrient losses in the form of the chemical fertilizers (21-0-0, 0-46-0, and 0-0-60), the quantity were 4 514 922.5 tonnes of 21-0-0 fertilizer, 849 891.3 tonnes of 0-46-0 fertilizer, and 562 844.4 tonnes of 0-0-60 fertilizer for N, P and K, respectively. Compared to the total of 3 939 376 tonnes of imported chemical fertilizers to Thailand in the year 2004, nutrient losses by crop removal or other losses still far exceed nutrient gained by fertilizer application or other soil improvement measures.

Not only removed with the yield, nutrients remained in crop residues which should be incorporated into the soil were also removed with the straw for other uses or burnt in the field. These old conventinal practices accelerate the nutrient depletion of the soil and put more tension in nutrient imbalance. Even though the methods of crop residue incorporation, composting, and green manure were recommended for soil improvement for decades, only a small portion of the farmers adopted the techniques. There are many underlying reasons for the non-adoption of the techniques, but mainly tedious work and high practical cost involved. Large amount of organic materials must be used in order to increase significant yield, and will entail high cost. The difficulty in applying the bulky compost and the high labour cost for compost application are among the other reasons.

Today, the farmers who are used to produce compost themselves face the new problem of the scarcity of raw materials for composting. Many agricultural wastes such as bagasse, rice husk, eucalyptus bark, and sawdust, which used to be available for composting or soil amendment, are now being used as fuel for electricity and other industries especially the sugar industry, pulp and paper industry, ethanol production industry or the electrical production industry. It is possible in the near future that cheaper organic material for soil improvement may be hardly available for the farmers in Thailand.

Green manuring is the promising technology to counteract high energy cost. The escalating price of inputs, scarcity of organic wastes and the need of soil productivity improvement will drive this technology to the forefront for soil improvement. In the past, this practice was not widely practiced in Thailand. The farmers in irrigated areas used their lands intensively and did not allocate periods for planting green manure. In rainfed areas, the farmers did not have enough water to grow the plants for green manure especially in the Northeastern region of Thailand where the soil is sandy. Availability of legume seeds for green manure was another difficulty faced by farmers, as well as the lack of effective rhizobium strains available for legume inoculation. In surveying for nodulation of green manure legumes this year, it was found that most legumes had very low nodulation and the nodules were mostly ineffective. Both nitrogen fixation and growth of legume were very poor under ineffective nodulation. Selection of effective rhizobium strains for legume inoculation will be the most effective method in supporting the growth of green manure legume and supplying N to the soil. Effective rhizobium strains for green manure legume are now available for some legumes and researchers still select for others. Supplying nitrogen to the soil through green manure will be the most efficient technique as a substitute for chemical nitrogen fertilizer for farm land under the “National Agenda on Organic Agriculture” strategy of Thai government.

3. National strategies to improve resources productivity and the efficiency of agricultural production

The concept to improve the agricultural resources for agricultural production efficiency, maintaining clean environment and enhancing the quality of agricultural products for consumers, have been strengthened in the last few years. Many strategies were implemented by the government to achieve the targets. A four-year plan on “The National Agenda on Organic Agriculture” was one of the strategies established this year. Under this plan, organic practices will be implemented by many government departments and a great number of local organic fertilizer factories with investments from the government will be established around the country. The prominent impact of the organic farming agenda is the vast improvement of the agricultural resources with organic matter or natural products. Even though the area planned to be organic farms is small compared to the total agricultural area of the country, the concept of resource improvement will be strengthened and a large number of organic fertilizer factories constructed around the country will have the impact on usng and lowering the price of compost in the country. Since many organic fertilizer factories will be set up around the country, all available large sources of organic wastes will be collected and utilized for compost production. As a result, off-farm abandoned organic wastes will be used as soil amendment for soil productivity. It seems to be the most promising strategy in supplementing plant nutrients, especially the minor and trace elements, which are not the component of chemical fertilizers to farm lands by using the overlooked off-farm organics. Clean environment and clean agricultural products are also the targets of the programme. The government also launched “Water Management Modernization” mega-project. This project is the national integration of water management which includes management of water reservation and delivery systems, management of all 25 watershed areas around the country, on-farm water management system, warning system, etc. These managements will alleviate most problems about water including the drought problem. With these strategies to improve both soil and water resources, more efficient agricultural production is expected and crop yield should be increased together with better farmer-livelihood.

4. Development of the integrated nutrient management

Along with many strategies of the country to improve the quality and availability of resources for agriculture, as well as upgrade the understanding and transferring the technology to the farmers, intensive experiments are performed in many aspects.

Site-specific nutrient management using information tools, and technology, is one example that performs well and shows high potential in the application for many crops. Attanandana et al. (2000, 2002a, 2002b) developed the method for fertilizer recommendation for maize production in the maize belt area of four provinces in Thailand. The method used decision support system based on fertilizer application experiments, soil and weather information, maize information, site-specific soil information including soil series, soil pH, N, P, K, simplified techniques and simplified soil test kits. The results showed that the fertilizer recommendation programme was very promising in increasing yields and farm profits, and also well adopted by the maize-grown farmers in the project.

Precision agriculture is another example in the integrated technologies for nutrient management in crop production. The cooperation between Kasetsart University, Thailand, and the University of Tennessee, USA, has developed the precision agriculture model for sugarcane production in the western region of Thailand. The programme incorporates global positioning system (GPS), geographical information system (GIS), fertilizer application experiments, and variable fertilizer applicator system for precise fertilizer application of sugarcane. The technology was very precise by dividing a 20 acres area or larger into small grids (20 x 20 m grids in the experiment plots) using the GPS. Sugarcane yield and yield-controlling factors of each grid were collected as geographical information. Variable rate fertilizer applicator was developed to use signal from GPS and information from GIS to control the rate of fertilizer application for each grid. Integrating the fertilizer response curve from experiments, the tractor equipped with GPS system, variable rate fertilizer applicator, and the control unit will apply the proper rate of fertilizer needed in each grid. With this technology, the application of fertilizer will be optimized to maximize the profit. The technology is not only useful for nutrient management but also for many other uses in agricultural practices. The experiment is still under development.

5. Appropriate solutions

Based on the problems of the conventional agricultural practices and the government strategies and technlogy development in Thailand, the noted problems and appropriate solutions can be summarized as follows:

• Understanding about soil and resource management is seriously needed for the farmers in Thailand.
• For effective technology transfer, extension officers must be trained specifically on soil, nutrient and fertilizer management topics before setting-up the programme for farmer’s training programme.
• Government strategies in agricultural resources’ quality improvement and expansion of the country’s irrigation system through “National Agenda on Organic Agriculture” and “Water Management Modernization” mega-project post a strong impact for Thai agricultural productivity in the near future.
• Well-educated farmers and well-trained extension officers are very important to support the government’s strategies in improvement of agricultural resources.
• Site-specific nutrient management, precision agriculture or similar technologies are very effective technologies in supporting the goal of the workshop programme in sustaining high crop yield, maximizing farmer net income, preventing land degradation and minimizing adverse impact of nutrient use on the environment.

Efficient integration between the understanding about soil and nutrient management of farmers, good technology transferring system, appropriate strategies of the government and the efficient nutrient management technologies will have the pronounced impact on food security in Thailand and the regions.

References

Attanandana, T., C. Suwannarat, T. Vearasilp, S. Kongton, R. Meesawat, P. Bunampol, K. Soitong, C. Tipanuka, and R.S. Yost. 2000. NPK fertilizer management for maize: decision aids and test kits. Thai Journal of Soil and Fertilizer 22: 174-186.

Attanandana, T., T. Vearasilp, and K. Soitong. 2002a. Decision support system for fertilizer application in maize production: faze III. Progress report.

Audthasit Wongmaneeroj and Chawalit Hongprayoon. 2004. Correlation and Spatial Variability of Soil Properties Affecting to Sugarcane Yield in Kamphaeng Saen Soil. Kasetsart J. (Nat. Sci.) 38: 109-112.