Dr. Sanjay Kumar Ray
ACTO (Soil Science),
KVK, ICAR Research Complex for NEH Region
1. Introduction: Nagaland is a mountainous state located in the North Eastern Hill region of India. Out of the total geographical area (TGA) of the state only 8.48% of the area are plain and the rest is constituted by undulating hilly terrain. The major problems with soils are strong soil acidity, low cation exchange capacity (CEC), very limiting soil depth in hill slopes, soil erosion and landslides, as a result of weak geological formations.
2. Essential Plant Nutrients: Plants require seventeen (17) essential nutrient elements to complete its life cycle. Further, these nutrients are classified into 2 groups: macronutrients (primary and secondary) and micronutrients. The primary nutrient elements are nitrogen (N), phosphorus (P) and potassium (K), because they are required in larger quantities than other nutrient elements. The management of these nutrients is very important for optimum crop production. The secondary nutrient elements are calcium, magnesium, and sulphur that are applied through fertilizers and soil amendments. The remaining essential elements are the micronutrients (Fe, Mn, Cu, Zn, B, Mo, Cl and Ni) that required in very small quantities.
3. Deficiency & Toxicity Symptoms in Plants: In the absence of any particular nutrient in the right concentration, plant shows some visual deficiency symptoms. Similarly, excess quantity of a certain nutrient is also harmful and upon such situation plant shows toxicity symptoms.
4. Limitations of Crop Production in Nagaland: Limited or no application of manures and fertilizers, soils have failed to sustain the yield level on a long-term basis and consequently emerged multiple nutrient deficiencies, irrespective of soil type. Further, soil acidity, toxicity of Al & Fe and deficiency of nitrogen, phosphorus, potassium and micronutrient like zinc, boron and molybdenum are very much common.
4.1. Soil Acidity: Formation of acidity is due to the rapid rates of weathering of acid parent materials (Tipam group and sandstones) undulating topography and higher intensity of rainfall which causes the leaching losses of exchanges bases from the surface soil. Toxicity of aluminium (Al) in acid soils has been recognized one of the important factors limiting the productivity particularly in the soils having a pH of below 5.5. About 83.6 % of soil pH of Nagaland is falls below pH value of 5.5. Niuland, Dhansiripar, Jakhama, Chiephebozou, Kohima, Ongpangkong South and North, Changtongya, Kobulong, Wakching, Tizit, Mon, Pomching, Kikruma, Pfutzero, Sekruzu, Chessore, Shamator, Longkhim, Chukitong, Wokha, Sanis, Bhandari, Suruhuto, Akuluto, Tening, Longleng, Pungro, Kiphire blocks of Nagaland are severely affected by soil acidity (NBSS & LUP, 2014).
4.2. Soil Nutrient Deficiency: Soils of Nagaland are generally deficient in N, P, K, Zn & B. The maximum extent of deficiency of nitrogen (N) in soils are 34.4% of TGA at Sekruzu block of Phek district, whereas soils in 60.1% of TGA and 56.5% of TGA at Dhansiripar block of Dimapur District is suffering with low phosphorus (P) and potassium (K) respectively. Availablity of zinc (Zn) in soils were also found deficient upto 37.0% of TGA at Niuland block of Dimapur district.
5. Management Strategy: Some of the management strategies are highlighted below.
5.1. Soil Acidity Management: Soil pH of 6.0-7.5 are ideal for crop growth. Accordingly, the management of soil acidity is very important and is a great challenge, particularly in the high rainfall and mountainous areas like Nagaland. Application of 100% required doses of liming material to ameliorate acid soil are very much expensive affairs, which is not affordable to the poor farming community. Therefore, the aim should raise the soil pH around
5.5 to eliminate only Al toxicity at the root zone to obtained optimum harvest. Lime sludge of paper mill is also better to agriculture lime because it is having high (30 to 35%) calcium content, besides this, application of wood ash, biochar, charcoal is an alternative option can also be improved pH of the soil.
5.2. Nutrient Deficiency Management: Crops requires judicious application of mineral nutrients for proper growth, development and sustained quality production. The combined application of NPK chemical fertilizers and organic manures as an integrated manner can enhanced nutrient use efficiency, maintained soil health and increased crop productivity. A variety of biofertilizers that could be applied such as nitrogen fixers (Rhizobium, Azotobacter, Azospirillum), phosphate solubilizing bacteria (PSB), blue-green algae, mycorrhizae, plant growth promoting rhizobacteria (PGPR), etc.
5.3. Micronutrient Management: Plants absorb fertilizers directly when applied to their foliage as an aqueous solution. This method can be used for any plant nutrient, but commonly employed in case micronutrients which are required in relatively small amount and therefore, micronutrients are applied through foliar spraying.
6. Conclusion: Soil Nutrient management is a challengeable task particularly in the dynamic landscape with its steep slopes and heavy rainfall. More than 80% soils of the state are strongly acidic in nature besides deficient in macro and micronutrients. Therefore, a holistic, cost effective and area specific (block-wise/cluster-wise) approach needed to be adopted for managing of soil acidity and deficiency of nutrients for optimization crop production. Locally available nutrient resources should always be preferred along with the external nutrient inputs to make the farming system more sustainable.