Managing Soil Acidity for Food Security

Every year, December 5, is being celebrated as world soil day. This is the day for all soil lovers including scientists, policy makers, students and farmers to talk about the importance of soils for agriculture in general and food security in particular. This day highlights the soil's importance on Earth. Soil provides habitat for most living creatures in the earth and support production of foods and feeds. Considering its importance, the United Nations started celebrating World Soil Day since December 5, 2012, corresponding with the birthday of Thai king Bhumibol Adulyadej, who officially sanctioned the event. However, the history goes back to 2002, when the international Union of Soil Sciences (IUSS) made a resolution to propose December 5 as World Soil Day. After IUSS recommendation, FAO also supported the celebration of World Soil Day. In December 2013, UN General Assembly at the 68th session declared December 5 as World Soil Day. The first celebration was done in 2014. Since then, the world soil day is being celebrated annually with different theme.

For this year 2021, it is being celebrated with the theme 'Halt Soil Salinisation, Boost Soil Productivity' with the aim to raise awareness on the importance of managing salinity for soil health and crop productivity. In the context of Nepal, soil acidity is more problematic the salinity. Thus, the theme has been modified to “Halt Soil Acidification; Boost Soil Productivity” to raise awareness on soil acidity and its impacts on crop productivity. Soil acidity is one of the major issues for soil health and increasing crop productivity. National Soil Science Research Center (NSSRC) has organized different events to celebrate the day in collaboration with Department of Agriculture, Central Agricultural Laboratory, National Farmers Commission, FANSEP, PMAMP and Nepalese Society of Soil Science. The celebration begun with soil testing campaign at Banepa, potato zone on 1^st of December. On December 2, there was a special discussion in Krishi TV about World Soil Day and also a press meet was organized at the Department of Agriculture, Hariharbhawan. On the 3^rd of December, a conference on “Management of Soil Acidity for Prosperity” was held at National Soil Science Research Centre, NARC where 4 papers on soil acidity issues were present. Similarly, on the 5 December, a walkathon and discussion on contemporary issues of soil acidity along with closing ceremony will be held at Department of Agriculture, Hariharbhawan.

About 53% of the soil is acidic in Nepal. Managing soil acidity is critical to increase soil fertility and crop productivity as it affects nutrient supply to plant vailability vis-à-vis crop productivity. Government of Nepal has identified it as the major issue since long but the recurrence of acidity has been a major threat. Various natural and anthropogenic activities such as imbalanced fertilization has intensified acidity in Nepalese soil. Some of the other reasons are, low use of organic matter, low or no use of basic cations, continuous use of only acid forming chemical fertilizers, leaching of bases in slopy areas, etc. Increasing acidity reduces supply of plant nutrients and reduces crop productivity.

Management of soil acidity is crucial for boosting crop production and productivity. Without managing soil acidity, farmers may not able to achieve potential yield event with application of right amount of fertilizers. Application of liming materials is an effective method for managing soil acidity. Another option could be applicaiton of sufficient amount of organic inputs in soils including well decomposed farm yard manure, compost, ash, biochar, green manuring.

In addition, farmers can select right type of crop and varieties that can tolerate soil acidity so that they can achieve good yields. However, farmers are not much aware about these options. Hence, GoN, and other development parthers should raise awareness program at farmers level.

Recenly, National Soil Science Research Center has launched digital soil map of nepal. Farmers can easily know their soil acidity using Digital Soil Map (https//:soil.narc.gov.np).Based on the soil information through Digital soil map, extension workers should help farmers to identify different options of manading soil acidity. For this, GoN has to ensure availability of quality liming materials at farmers‘ door step. Despite the GoN recommendtion on use of liming materials, soil acidiy problem in not reduced. This is mainly due to unavailability of liming materials and farmers poor anwreness on its use. Most farmers donot realize its importance in soil health and increasind crop productivity.

Research institutions should identify appropriate dose of lime for each crop based on severity of acidity and identify right applicaiton timing. To increase effectiveness of liming, it shold be used judiciously. Farmers are reluctant to use lime because of higher dose (3-5 ton per hectare) which ultimately increase their cost of production. Timing of application is another factor, farmers are always in hurry to catch the next crop and therefore, waiting period after liming for 3-4 weeks sometime delays planting time.

In Nepal, officially only two agricultural lime industries are in function. There are also other local crushers who supply liming material in nearby locality but the quality of the liming material produced from such unauthentic source remains a question. Government should monitor such producers, guarantee the quality and mainstream them as per standard guidelines. The government has subsidized agricultural lime but the cost is higher due to high transportation cost incurred. Government of Nepal has many policies but policy to support sustainable soil management is lacking. In order to manage soil acidity problem in Nepal, a liming policy has to be drafted and implemented at the earliest so that all municipalities can formulate and execute liming program accordingly.

By Dr. Shree Prasad Vista, Chief, National Soil Science Research Centre, NARC, Dr. Yam Gaihre, Soil Scientist, International Fertilizer Development Center (IFDC), Dr. Nabaraj Pandit, Soil Scientist, International Maize and Wheat Improvement Center (CIMMYT), Ms Shova Khadka, Agriculture and Forestry University, Rampur