Integrated nutrient management and sustainable agriculture
Current issues and future challenges in North East Himalayan region

MA Ansari, LK Baishya, PK Sharma , N Prakash *

A participatory nursery of NAP Kamu Lairok village at Thoubal Division :: Pix - Manipur Forest Department

One of the most important challenges facing humanity today is to conserve/sustain natural resources, including soil and water, for increasing food production while protecting the environment. As the world population grows, stress on natural resources increases, making it difficult to maintain food security. Long term food security requires a balance between increasing crop production, maintaining soil health and environmental sustainability.

In India, effective nutrient management has played a major role in accomplishing the enormous increase in food grain production from 52 million tons in 1951-52 to 252 million tons during 2011-12. During the period 1960-61 to 2011-12, food grains production grew at a compounded annual growth rate (CAGR) of around 2 per cent.

In fact, the Ninth and Tenth Five Year Plans witnessed agricultural sectoral growth rate of 2.44 per cent and 2.30 per cent respectively compared to 4.72 per cent during Eighth Five Year Plan. During the 11th Five Year plan, agriculture grew at a rate of 3.28 per cent as against a target of 4 per cent.

However, application of imbalanced and/or excessive nutrients led to declining nutrient-use efficiency making fertilizer consumption uneconomical and producing adverse effects on atmosphere and groundwater quality causing health hazards and climate change.

In North Eastern Himalayan Region (NEHR), the jhum land's soil fertility status has become depleted after years of exploitation with no addition of manures and inadequate management practices.

On other hand, nutrient mining has occurred in north eastern hilly soils due to lack of affordable fertilizer sources and where fewer or no organic residues are returned to the soils, especially under jhum areas. In NEH states of India, jhum is the prevalent and soils are inherently poor in organic matter, fertility and water-holding capacity. In these soils, N, P, K and S as well as micronutrients deficiencies are principal yield-limiting factors for crop production.

INM entails the maintenance/adjustment of soil fertility to an optimum level for crop productivity to obtain the maximum benefit from all possible sources of plant nutrients – organic as well as inorganic – in an integrated manner, and is an essential step to address the twin concerns of nutrient excess and nutrient depletion. INM is also important for marginal farmers of hilly areas who cannot afford to supply crop nutrients through costly chemical fertilizers.

A soil's potential for producing crops is largely determined by the environment that the soil provides for root growth. Roots need air, water, nutrients, and adequate space in which to develop. Soil attributes, such as the capacity to store water, acidity, depth, and density determine how well roots develop. Changes in these soil attributes directly affect the health of the plant. For example, bulk density, a measure of the compactness of a soil, affects agricultural productivity.

When the bulk density of soil increases to a critical level, it becomes more difficult for roots to penetrate the soil, thereby, impeding root growth. When bulk density has increased beyond the critical level, the soil becomes so dense that roots cannot penetrate the soil and root growth is prevented. Heavy farm equipment, erosion, and the loss of soil organic matter can lead to increases in bulk density. These changes in soil quality affect the health and productivity of the plant, and can lead to lower yields and/or higher costs of production.

Integrated nutrient management

The main aim of sustainable agriculture is; successful management of resources, satisfy the changing human needs, maintain or enhance the quality of environment and conserve natural resources. Integrated nutrient management (INM) is an integral part of sustainable agriculture which requires the management of resources in a way to fulfill the changing human needs without deteriorating the quality of environment and conserving vital natural resources.

It refers to the maintenance of soil fertility and of plant nutrient supply at an optimum level for sustaining the desired productivity through optimization of the benefits from all possible sources of organic (farm yard manures, poultry manures, crop residues, green manures), inorganic and biological (biofertilizers etc.) components in an integrated manner.

Concepts

* Regulated nutrient supply for optimum crop growth and higher productivity.
* Improvement and maintenance of soil fertility.
* Zero adverse impact on agro – ecosystem quality by balanced fertilization of organic manures, inorganic fertilizers and bio- inoculant
* To improve the stock of plant nutrients in the soil
* To improve the efficiency of plant nutrients, thus limiting losses to the environment

Why Integration for sustainable agriculture?

* Avoid multiple nutrient deficiencies
* Higher productivity and cropping intensity
* Only organic sources insufficient for nutritional needs of high yielding varieties.
* Organic sources with mineral fertilizers became necessary
* Alternative Source of Energy for Farmers
* Green manuring crops can grow in lean period for 40-50 days
* A need of integrating organic sources with mineral sources for supplementing plant nutrients need

Determinants

* Nutrient requirement of cropping system as a whole.
* Soil fertility status and special management needs to overcome soil problems, if any
* Local availability of nutrients resources (organic, inorganic and biological sources)
* Economic conditions of farmers and profitability of proposed INM option.
* Social acceptability.
* Ecological considerations.
* Impact on the environment

Advantages

* Enhances the availability of applied as well as native soil nutrients
* Synchronizes the nutrient demand of the crop with nutrient supply from native and applied sources.
* Provides balanced nutrition to crops and minimizes the antagonistic effects resulting from hidden deficiencies and nutrient imbalance.
* Improves and sustains the physical, chemical and biological functioning of soil.
* Minimizes the deterioration of soil, water and ecosystem by promoting carbon sequestration, reducing nutrient losses to ground and surface water bodies and to atmosphere

In order to meet the food demands of a rising population in the first decades of the 21st century, farmers must manage nutrients and soil fertility in an integrated way. Required yield increases of major crops cannot be attained without ensuring that plants have an adequate, balanced supply of nutrients. This balance will not be achieved until "nutrient cycles" are better understood, an issue that government should address by establishing testing and monitoring systems.

Government and extension services will need to facilitate adoption of nitrogen- fixing species among farmers. Government will also need to continue to facilitate the widespread and responsible use of organic and inorganic fertilizers. Nutrient depletion through soil mining is an especially acute problem in parts of NEHR and special steps to combat it are required there.

These efforts include soil testing for nutrient depletion, cooperation between farmers and researchers, promotion of more productive use of organic nutrients, and encouragement of extension services and NGOs to pay attention to soil- related issues. Efforts may also include government and NGO- supported investments to enhance soil fertility.

Integrated nutrient management can address many of the problems besetting poor, small holder farmers in NEH and elsewhere. But INM's success ultimately depends upon the timely and concerted efforts of extension programs, government, NGOs, researchers, and the farmers themselves.