2. Integrated Nutrient Management (Nutrient Management Plan ) A Series of Lecture By Mr. Allah Dad Khan

3. Mr. Allah Dad Khan

4. What is nutrient management? Nutrient management is the process of managing the amount, source, timing, and method of nutrient application with the goal of optimizing farm productivity while minimizing nutrient losses that could create environmental problems. It includes developing nutrient budgets that consist of knowing the amounts of nutrients present in the soil, determining the amount of nutrients needed by the crop, accounting for all the potential sources of nutrients, and then applying manures, composts, irrigation water, or inorganic fertilizers to meet the nutrient need of the crop. It also uses site management practices to increase or maintain soil quality to reduce the potential for erosion and nutrient transport into surface water or nutrient leaching into groundwater. Soil quality is an important component of nutrient management because it affects nutrient retention and water movement through the soil. Biosolids are applied to a crop field in the photo at right.

5. Why use nutrient management? Farmers need to apply nitrogen, phosphorus, potassium and other nutrients to achieve desired crop growth and yield. However, excessive nutrient application can have negative environmental impacts. Nutrients that are not efficiently used by crops or retained in the soil can leach into groundwater and move from agricultural land into surface waters. For example, excess nitrogen in the form of nitrate can leach through the soil into groundwater. Concentrations of nitrate in drinking water above the national drinking water standard of 10 mg/L can cause health problems for infants and elderly people. Nitrate- nitrogen concentrations of 20 to 40 ppm or mg/L can cause health problems for horses and ruminants.

7. How is soil affected? The key to good soil quality is soil organic matter. A sufficient amount of nutrients in the soil, particularly nitrogen, is necessary to form and maintain soil organic matter. A fertile soil has greater plant growth, which can create greater inputs of roots and other plant debris into the soil. This plant debris undergoes decomposition and adds to the soil organic matter. Applications of animal manures and composts, as well as the use of cover crops, all help increase soil organic matter. Organic matter provides a food source for soil microbes and increases microbial activity. As the microbes breakdown organic matter, nutrients are released in forms that the plants can utilize. Because nutrient management accounts for the nutrients added to the system, it promotes increasing soil quality without creating nutrient excesses.

8. How is soil affected? Different soils have different capacities to adsorb and retain nutrients. This is related to the amount of soil organic matter and the soil texture (percent sand, silt, clay). Because the soil texture cannot be changed, increasing soil organic matter is the best way to increase the capacity of a soil to retain nutrients. Soils with larger amounts of soil organic matter and at a near neutral pH will have a greater capacity to retain nutrients, thus a higher soilquality than soils with low organic matter.

9. How is soil affected? Though soil organic matter can also retain some negatively charged nutrients such as phosphorus, the clay and carbonate content of the soil has a greater impact on nutrient retention. Aluminum and iron oxides found in clayey soils readily bind phosphorus; consequently, soils with greater percent clay can retain higher concentrations of phosphorus than other soil types. Soils with high carbonates also tend to bind phosphorus and reduce its loss. Sandy soils have fewer iron and aluminum oxides, therefore, have a lower capacity to retain phosphorus. If phosphorus is over-applied (which can happen when manures are used to meet the nitrogen need of a crop), the capacity of the soil to bind phosphorus can be exceeded. In these cases, the soil no longer functions as a nutrient buffer, soil quality is reduced, and water quality can be impacted.

10. How is soil affected? In areas where wind erosion is a problem, the aggregation of soil particles by soil organic matter, can also help reduce soil loss due to wind. Excessive tillage and the lack of residues or cover crops decrease soil organic matter and increase both wind and water erosion. Part of a nutrient management plan might be to change management practices to build or maintain soil organic matter to reduce erosion or establishing buffers to remove nutrients as water moves through the buffer. The management changes will be specific to the soil type, slope, and crops grown. The photo at right shows a conservation buffer adjacent to a crop field in Iowa.

13. How is soil affected? Because soil quality affects how water moves into surface and groundwater, it plays an important role in the site management practices of a nutrient management plan. Soil organic matter helps sustain microbial activity, which in turn tends to create soil aggregates by generating polysaccharides and other compounds that “glue” soil particles together. These aggregates can help prevent soil crusting and promote better soil structure, which leads to easier root penetration, as well as improved plant growth and production. Within a soil textural class, higher soil organic matter and better aggregation will allow more water to infiltrate into the soil, reducing erosion and preventing the loss of nutrients.

14. How to monitor the soil The best way to determine the nutrient content of the soil is by testing. Soils should be tested every 1-3 years based on the soil type and state requirements or recommendations. Soil tests usually report pH, phosphorus, potassium, calcium, magnesium, sulfur, and micronutrients. In some states, the level of soil nitrate nitrogen may also be reported. From soil analyses, nutrient recommendations can be offered based on local field trials and the experience of the land grant university. All this information helps the farmer know how much lime and fertilizer is needed for a particular crop on a particular soil.

15. Elements of a Nutrient Management Plan Nutrient management consists of several steps: Testing the soil to determine the nutrient supplying power of the soil,Determining the recommended amounts of nutrients needed to produce the desired yields,Accounting for nutrient inputs from other sources, such as legumes,Analyzing manures, composts, and irrigation water to determine the nutrient content, Applying manures or composts at recommended rates and based on the critical nutrient (usually either nitrogen or phosphorus),Applying the additional inorganic nutrients as needed,Keeping records so evaluations and adjustments can be made, and Being aware of your surrounding landscape so sensitive areas can be protected.

16. Local considerations The specifics of a nutrient management plan are dependent on soil types, cropping systems, and site conditions such as topography and hydrology. Each state has their own specific procedures for developing a nutrient management plan based on their research and experience.