Chapter 3 - Green Manuring, Fertilizer recommendation approaches & INM| Unit I Notes - Fertilizers and Soil Fertility Management

Unit-I Syllabus

Fertilizers and Soil Fertility Management

Chapter 3

Green/Leaf Manuring, Fertilizer recommendation approaches and Integrated nutrient management

Green/Leaf Manuring

Green or leaf manuring is a process of using green plant materials as a source of organic matter and nutrients to improve soil fertility. This technique involves growing specific types of crops and then incorporating them into the soil before they mature or produce seeds.

Green manuring is typically done by planting leguminous crops like clover, alfalfa, peas, or beans, as these plants have the ability to fix atmospheric nitrogen in their roots. When these plants are incorporated into the soil, they release nitrogen and other essential nutrients, which are then available to the next crop.

The benefits of green manuring include:

  1. Improved Soil Fertility: Green manuring helps to replenish soil nutrients and improve soil structure, which in turn increases the soil's ability to retain water and nutrients.
  2. Reduced Soil Erosion: The cover crop helps to protect the soil from erosion by wind and water.
  3. Pest and Disease Control: Certain green manure crops can help to reduce pest and disease problems in the soil.
  4. Reduced Need for Fertilizers: The nitrogen and other nutrients released by green manure crops can help to reduce the need for synthetic fertilizers.

To implement green manuring, a farmer should select the right type of crop for their soil and climate conditions. The cover crop should be allowed to grow until it reaches the desired height, and then it should be cut or mowed and left to decompose on the soil surface for a few weeks. Once the green manure has decomposed, it can be tilled into the soil to improve soil fertility.

Overall, green manuring is a sustainable and effective way to improve soil fertility, reduce soil erosion, and reduce the need for synthetic fertilizers.

Fertilizer recommendation approaches

There are several approaches to making fertilizer recommendations for crops, including:

  1. Soil Testing: Soil testing is a common approach used to determine the nutrient levels in the soil. This involves taking soil samples from the field and analyzing them for pH, organic matter, and nutrient levels. Based on the results of the soil test, a fertilizer recommendation can be made that is tailored to the specific needs of the crop and soil.
  2. Crop Nutrient Removal: Another approach is to estimate the amount of nutrients that will be removed from the soil by the crop during the growing season. This can be done by calculating the crop yield and the nutrient concentration in the harvested portion of the crop. The fertilizer recommendation is then based on the amount of nutrients that will be removed by the crop.
  3. Yield Goal: A yield goal approach is based on the expected yield of the crop. The fertilizer recommendation is calculated based on the expected yield and the nutrient requirements of the crop. This approach takes into consideration the nutrient needs of the crop at different growth stages and the soil nutrient supply.
  4. Sufficiency Level: The sufficiency level approach is based on maintaining the soil nutrient levels at or above the critical level required for the crop. The fertilizer recommendation is made based on the difference between the critical level and the soil nutrient level.
  5. Chlorophyll Meter: A chlorophyll meter is a handheld device that measures the amount of chlorophyll in the leaves of the crop. This provides an indication of the crop's nutrient status and can be used to make fertilizer recommendations.

The choice of fertilizer recommendation approach depends on the specific crop, soil type, and growing conditions. It is important to select the most appropriate approach to ensure that the fertilizer application is optimized for crop growth and yield, while minimizing the risk of nutrient losses to the environment.

Integrated Nutrient Management

Integrated Nutrient Management (INM) is a holistic approach to nutrient management that combines various sources of nutrients to optimize plant growth, reduce nutrient losses, and improve soil health. The objective of INM is to provide the crop with the required nutrients in the right quantity, at the right time, and in the right form, while minimizing the environmental impact of nutrient use.

INM involves the use of organic and inorganic fertilizers, soil amendments, crop residues, and green manures to maintain soil fertility and improve nutrient use efficiency. The specific strategies used in INM may vary depending on the crop, soil type, and environmental conditions.

The key components of INM include:

  1. Soil Testing: Soil testing is the first step in INM. It helps to determine the nutrient status of the soil and the fertilizer requirements of the crop. Soil testing also helps to identify nutrient deficiencies, pH imbalances, and other soil-related issues that may affect crop growth and yield.
  2. Organic Amendments: Organic amendments, such as compost, animal manure, and crop residues, are valuable sources of nutrients and organic matter. These materials can improve soil structure, water-holding capacity, and nutrient availability.
  3. Inorganic Fertilizers: Inorganic fertilizers are a concentrated source of essential plant nutrients, such as nitrogen, phosphorus, and potassium. These fertilizers can be used to supplement the nutrient supply from organic amendments and to meet the crop's immediate nutrient needs.
  4. Crop Rotation: Crop rotation is a technique used to break pest and disease cycles, improve soil health, and maintain soil fertility. It involves growing different crops in a sequence on the same land, each with different nutrient requirements and effects on soil health.
  5. Green Manuring: Green manuring involves growing cover crops, such as legumes, that are plowed under to add organic matter and nitrogen to the soil. This technique can improve soil structure, water-holding capacity, and nutrient availability.
  6. Precision Farming: Precision farming techniques, such as variable-rate fertilization, can be used to apply fertilizers in the right quantity and at the right time, based on the crop's nutrient needs and soil nutrient supply.

Overall, INM is an effective approach to nutrient management that can improve crop yield, soil health, and environmental sustainability. By integrating different sources of nutrients and adopting sustainable practices, INM can help farmers to optimize nutrient use efficiency and reduce the risk of nutrient losses to the environment.

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