5. Integrated nutrient management for dryland agriculture

Transcript

Hi Friends in the previous lectures, we have studied about the cropping systems. We have studied the cropping systems in relation to their production technologies. And also crop interaction, and also crop management. And what are the types of cropping systems. How we have to select the cropping systems for a particular season or particular region. So in this lecture let us study about the Integrated Nutrient Management for drylands. So Integrated Nutrient Management for drylands, the concept is here,

• The use of mineral fertilizer is the quickest way to increase the crop production.
• High cost, unavailability and risk and soil related problems.

No doubt the mineral fertilizer is a quickest source of providing nutrients or food to the plants. But they are highly costly and their unavailability make the farmers desist from using the mineral fertilizer. Then what’s the way out. Here comes the ‘Integrated Nutrient Management’. What is meant by Integrated Nutrient Management? It is combining all the available sources of nutrient supply and performing that tragedy into the dryland agriculture, It may be chemical fertilizers. It may be organic fertilizers. It may be biological fertilizers. All these will be used in an optimum way.

It is called as Integrated Nutrient Management. Integrated Nutrient Management it focuses on maintaining the soil fertility and also plant nutrient supply, so as to sustain the production system. In the Integrated Nutrient Management mainly it is focused on maintaining soil fertility and also plant nutrient supply, so as to produce sustainable production system. The second one is cropping system approach. It doesn’t focus on the single crop system. So it maintains, it mainly orients towards the cropping system approach instead of single crop. Then third one is, does not preclude the use of chemical fertilizers. There is a notion that in the Integrated Nutrient Management system, chemical fertilizers will not be used. No it is not true. Here also the chemical fertilizers are used, but at a minimal rate. Then optimal use of renewable nutrient sources and minimal use of fertilizers. Here in the INM strategy most emphasis will be given towards the renewable nutrient sources, and very minimal strategy and the use of minimal fertilizers.

Next coming to the, what are the sources of nutrients for the crop production. There may be N number of sources, many sources for the crop production as nutrients. Let us see some of them. Soil organic matter, soil reserves, organic manures, biological nitrogen fixation, mineral fertilizers and the precipitation. Mainly nutrients, whenever you say the nutrients, immediately the mineral fertilizers come into the picture that are chemical fertilizers. Nitrogen, phosphorous, potassium and micro-nutrients. Along with this soil organic matter is also acts as a fertilizer, or organic manure. Then the soil itself is having its own reserves, that can be used as the nutrients. Then apart from that we have a biological nitrogen fixation, wherein the various micro-organisms are involved in fixing up the nitrogen and also other nutrients, so it also can be used biological nitrogen fixation.

Then coming to the organic manures. Many organic manures are there which also be used as source of nutrients. Then coming to the biological inputs for nutrient managements. What are the biological inputs for nutrient management? Here the biological processes are decomposition, immobilization and mineralization. Whereas in the decomposition of plant and animal residues, many micro-organisms are involved in the soil. Whenever the crop stubbles are left on the field and they are ploughed back into the soil, these micro-organisms; they decompose the plant residues into a finer forms, and from these, nutrients will be available to the plants. The second one is nutrient flow. These micro-organisms regulate the nutrient flow by way of immobilization and also conversion of carbon, hydrogen and oxygen into useful form that is called as mineralization. So the biological process by the micro-organisms involves nutrient flow, immobilization and mineralization. By these processes the micro-organisms makes the nutrients available to the plants. Then coming to the beneficial micro-organisms, symbiotic nitrogen fixers. In this rhizobium and brady rhizobium which are mainly the symbiotic nitrogen fixers. By this the nitrogen will be fixed to an extent of 120 kg per hectare. And it acts as a legume nitrogen economy.

Coming to the non-symbiotic fertilizers. This is mainly followed in case of cereals, azospirillum, azotobacter are the main non-symbiotic nitrogen fertilizers, which have also main role in fixing the nitrogen. Then coming to the phosphate solubilizing micro-organisms. It makes the yeast, fungi and bacteria type of micro-organisms. They make the insoluble phosphorous to soluble and make available to the plants. Then PGPR(Plant Growth Promoting Rhizobia) it is called as PGPR. These PGPR acts through the hormonal effect and makes disease severity and they will ward of the disease severity. This PGPR acts hormonal effects and they make a warding of the disease severity.

Then Vesicular Arbuscular Mycorriza. This is vesicular type. This is arbuscular type. They act as food. They will help in uptake of phosphorous fertilizers. So these are the biological inputs for the nutrient management. Coming to the use of bio-fertilizer for the seed inoculation. These bio-fertilizers are mainly used by the seed inoculation.

• The rhizobium inoculation is practiced to ensure adequate N. Nutrition of legumes instead of fertilizer nitrogen. For as far as legumes are concerned, mineral nitrogen is avoided since these bacteria are able to fix up the nitrogen by formation of nodules in the soil. So rhizobium inoculation is practiced to ensure the adequate N nutrition in case of legumes.
• Then in this select the right type of inoculant as different crops require different rhizobia. In case of legumes; different legume crops especially the pulses are particular about different strains of rhizobia. So we have to select different type of, different strains of rhizobia before the inoculation.
• How the inoculation will be done. Then prepare the inoculum and the jaggery solution will be made, that sticking agent.
• Then these seeds are mixed with the inoculum slurry. Then they are dried. And sow the seeds within 48 hours of the inoculation.

So what is the effect. What is the most advantage of the use of bio-fertilizer? Legumes grown in rotation or as inter-crops increase crop yields of succeeding non-legume crops to the extent of 0.5 to 3 tons per hectare, saving up to 120 kg of N per hectare, compared to sequential cropping of non-legume crops. When the legume crops are grown as inter-crops, or when the legume crops are taken as preceding crops in case of sequential cropping, they help the succeeding non-legume crop to the fixing of the nitrogen to the extent of 130 kg N per hectare. Or when we taken up as a inter-crop, they help in component crops in fixing the nitrogen.

So invariably in case of dryland systems, legumes should be involved in the cropping systems, because nitrogen economy can be achieved. Then organic inputs for nutrient management.

• Here organic manure: FYM and composts and oil cakes are used.
• Mainly in this organic nutrient management, the FYM is the most used organic manure and crop residues can be recycled by the composting.
• Combination of crop residue, fallowing and green manuring can be used to maintain the organic matter levels in the soil.

The organic inputs as a nutrient management is mainly used for the purpose of maintaining organic matter levels in the soil. That is the life of the soil. So if the appreciable quantities of organic matter content is there in the soil, we can sustain the soil and the plant growth. So what are the inputs; organic manures that is FYM, compost and oil cakes. Oil cakes are concentrated organic manures. So a combination of these will help to maintain the organic matter content in the soil. So in addition to this how they will be helpful in the crop growth. They increases the biological activity, reduces the nitrogen losses and improves the performance of micro-organisms. These organic nutrient elements when they are incorporated into the soil, they mainly improve the activity of micro-organisms. That is the first and foremost important process they will bring about. When the activity of the micro-organisms is increased, the biological activity will be increased, and nitrogen losses will be reduced to the immobilization. So through these three processes organic matter contained will be maintained in the soil.

Then coming to the mineral fertilizers for the nutrient management. Which is also a component in the case of Integrated Nutrient Management.

• Use of appropriate mineral fertilizers to meet the demand for the necessary nutrients. We have to use it appropriately and not in a high quantity.
• Ensure that efficiency of applied fertilizers is optimized through adoption of suitable practices. Whenever you use it as mineral fertilizers for use, they have to be used very carefully, because they should be used, they should be applied with a proper method, proper form and in a proper quantity. What is the form or type as recommended for the crop? Whether it is in a granular form or type of the fertilizer, that is dependent upon the crop demand.
• Then coming to the method—furrow placement and covering with the soils. It can be applied in the furrows and immediately the fertilizer is covered with the soil. This furrow method is useful in increasing the fertilizer use efficiency.
• Then the time of application, this is also important. Instead of blanket application of nitrogen fertilizers. The nitrogen fertilizers have to be applied in 3 doses, mainly to avoid the losses of nitrogen fertilizers. As they are highly volatable. If you apply one time all the part of, quantity of the nitrogen available to plants will be very minimal. In this way split doses can be followed.
• Quantity—when you come to quantity, it should just be sufficient to meet the plant demand. That’s all. It should not be applied too much and it should not be applied too less. Whatever the crop demand is there, that has to be satisfied by the application of mineral fertilizers.

Then in case of drylands, there is a provision to make on farm production of compost. This is very important. This is nothing but the planting of green manure trees on field bunds for on farm production of biomass and compost and modifying the microclimate. What it happens in case of drylands on the field bunds. 3 to 4 species of green manure crops are planted during the kharif. Subsequently a pit is opened; compost pit is opened in the nearby dryland flat. After the harvest of the leaves and figs, they will be composted. This composted manure will be used for the dryland crops during the next cropping season. So in this way on farm production of biomass as well as compost. First biomass will be produced, then it will put into the compost pit, and the compost will be prepared and it will be used as a manure for the crops.

So leaves obtained can also be incorporated into the soil by suitable method. This is one of the methods in case of drylands, on farm production of biomass and compost. And it also improves the micro-climate. This we can see that on the crop bunds leaf cdi is grown, and this produces very high biomass. And this is put into the compost pit and make a compost, and this can be used. Otherwise these leaves can be cut and incorporated in a soil. Both ways it can increase the biomass and improve the organic matter content.

So advantages of on farm production is that

• It increases the soil fertility and the microbial activity in the soil. Any compost, any crop stubble, any organic matter, when they are incorporated into the soil, immediately the activity of the micro-organisms will be increased. When the activity of the micro-organisms is increased, subsequently the mineralization of the nutrients takes place.
• Second thing is reducing of the soil erosion. Because they have been planted in the bunds, they resist the soil erosion. They won’t allow the soil particles to detach. In this way it also reduces the soil erosion.
• Then increases the water holding capacity of the soil. Whenever these organic manures are incorporated, they hold the moisture. They have some characters which bind the water molecules. So water holding capacity of the soil increased. By all this the microclimate of the soil also be increased.

So to the conclusion. The soil moisture is very limiting in drylands. That’s a very known fact. Availability of the nutrients becomes limited because of the limited soil moisture. For this a proper mixing of organics and inorganics would be desirable in case of drylands. So INM practices holds the key in case of drylands. Second thing is that nutrients like potassium helps to increase the drought tolerance, by affecting the plant-soil-water relations besides yield advantage. Some of the nutrients besides the yield advantage, they have a specific character. In that the potassium improves the drought resistance, so that it can be applied very frequently.

Then third one is management of legumes in crop sequences/inter-cropping for their residual effect. Because I have already told you these legumes will help in nitrogen fixation in the soil. They will help in the nitrogen economy. So invariably legumes have to be incorporated in the cropping plan. So INM is essential to maintain the soil fertility, and increase the food production without harming the environment. So Integrated Nutrient Management is a strategy wherein soil fertility will be maintained and increase the food production without harming the soil environment. In this way INM will help in boosting the production in case of drylands.

Thank You.