Orchard Management (1+1)

INTEGRATED NUTRIENT MANAGEMENT

Introduction:

• In case of integrated nutrient management, all types of nutrients are supplied in the form of organic or inorganic manures and fertilizers to maintain uniform soil fertility.
• Continuous use of fertilizers spoils the soil structure and soil becomes unproductive in due course.
• Fertilizers applied along with sufficient quantities of organic manures will improve the efficiency of the fertilizers. Green manuring (Plate 11.1) should be done every year or once in two year during the rainy season.
• Suitable bio-fertilizers should also be applied from time to time.

Plate 11.1: Fully grown green manure crop in the inter tree space

• Plants need adequate supply of sixteen essential nutrients for their normal growth and production, out of which carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) are needed in larger quantities and are referred as macro-nutrients, whereas, zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), boron (B), molybdenum (Mo) and chlorine (Cl) are required in smaller quantities and thus called as micro-nutrients.
• An essential element is distinguished from a non essential one on the basis of following criteria laid down by Arnon and Stout (1954):

i. The plant is unable to grow normally and complete its life cycle in the absence of the element.
ii. The function of the element is specific and cannot be replaced by any other element.
iii. The element plays a direct role in the metabolism of the plant.

• Carbon, hydrogen and oxygen are taken up by the plants from water and air; all other nutrients are drawn by plants from the soil.
• These elements are found in the soil in varying quantities depending upon the fertility of the soil. Fruit trees remove a large quantity of nutrient elements from the soil.
• Optimum doses of nutrients vary from crop to crop. For example, nitrogen requirement per hectare basis varies from 50 kg for mango to 650 kg for grapes, whereas P2O5 requirement varies from 30 kg for mango to 434 kg for papaya.
• Potassium requirements of fruit crops are much higher than that of nitrogen or phosphorus. Potassium is very important for fruit quality.
• Even fertile soils have a limited ability to cope with the nutritional requirement of plants.
• For healthy growth and optimal yield, nutrients must be available to plants in correct quantity, proportion and in a usable form at right time. To fulfil these requirements chemical fertilizers or natural manures are needed.

• Fruit crops are mostly perennial and therefore, require long term nutrient management strategies.
• No single source of plant nutrients viz., fertilizers, organic manures, FYM, bio-fertilizers, green manure is capable to satisfy the crop requirements.
• Application of chemical fertilizers though, makes the soil fertile and increases productivity of plants, but also has an adverse effect on soil and environment.
• Organic sources have enormous abilities to improve physical properties of soil, but have meagre nutrient contents to meet nutrient needs of fruit trees, when used alone.
• It is important that fertility and productivity of the soil be restored/ maintained on sustainable basis by combining organic and inorganic fertilizers.
• Use of organic manures, apart from improving physical and biological properties of soil, helps in improving the use of efficiency of chemical fertilizers.

Therefore, there is a need to organize the supply of nutrients to crop through organic and renewable sources and strengthen the idea of ‘Integrated Nutrient Management’ (INM).

• Integrated Nutrient Management (definition): The combined use of different sources of plant nutrients i.e. organic, biological and inorganic amendments for the maintenance and improvement of soil fertility and plant nutrient supply at an optimum level for desired crop productivity may be termed as integrated nutrient management.

Needs for INM:

• Unbalanced use of N:P:K have caused detrimental long term effects on soil fertility.
• In areas subjected to intensive cultivation, application of mere chemicals is not sufficient for sustaining the yields, and it also leads to deficiency in the soil of secondary nutrients and micronutrients which limit crop productivity.
• Use of organic manure, crop residue and biodegradable rural and urban waste not only supplement the chemical fertilizers but also increase the efficiency in nutrient supply, leading to improvement of physical and biological properties of the soil.