To feed the burgeoning populations all over the world, we are striving to produce ever-bigger harvests with every passing year. In this process, increasing amounts of nutrients are being exported from agricultural soils. The big challenge ahead is how to maintain, rather enhance the fertility of our soils. How can we address this issue?
By applying mineral fertilizers in judicious amounts responding to the spatial and temporal variability affecting the crop. Without fertilizers, nature struggles to replenish the nutrients in the soil and would not be able to produce enough yields. Regarding soil health, incorporating biological and other sources of nutrient is a key factor not only to provide nutrients partially, but also taking care of the physical and biological aspects of the soil that is eventually reflected on enhanced soil health and high yields.
Soil is the living part of the earth crust. We consider it ends with the last visible root. There are 20 miles of rockbeds below every field. The question is not what is exported, but how deep you can get your roots. Do the math... you will see for yourself how ridiculous the exported element game is when you consider handling your cultural practice in favor of biology... We have the experience (about 30 years) of doing this. Read, and look at the biologic component of the soil fertility, take care of it and you will find out that the physical and chemical components will follow with no fertilization...
Sir, We want to listen from you because you are the right person to address. I would like to say that (1) STCR, (2) SSNM and (3) other methods of Precision Nutrient Management will be the right approach to supply the required quantity of nutrients. Further, for supply of nutrients, INM is the best approach for maintenance of soil fertility (in which a portion of nutrients should come from organic [20-30%] and biofertilizers [10-20%]).
Expecting your valuable remarks on my comments. Regards.
https://www.sare.org/Learning-Center/Books/Crop-Rotation-on-Organic-Farms/Text-Version/Physical-and-Biological-Processes-In-Crop-Production/Crop-Rotation-Effects-on-Soil-Fertility-and-Plant-Nutrition : (By Anusuya Rangarajan) Understanding the basics of how nutrients are added to and released from soil organic matter will help the farmer in choosing crop sequences and amendments to optimize organic crop fertility. Certain fractions of soil organic matter contribute to plant nutrition more than other fractions. To effectively plan organic crop rotations to meet crop nutrient needs, several factors should be considered. Legume crops, which capture atmospheric nitrogen and “fix” it into forms available to plants, can be used strategically in rotations to meet the needs of nitrogen-demanding crops. Cover crops used after a cash crop capture surplus plant-available nutrients and conserve these for following crops. Cash crops themselves vary in their nutrient demands https://www.sare.org/Learning-Center/Books/Crop-Rotation-on-Organic-Farms/Text-Version/APPENDIX-1-Characteristics-of-Crops-Commonly-Grown-in-the-Northeastern-United-States
Sir, I think we should follow site and crop specific nutrient management. Along with this we need to calculate right time, right rate, right source and right method of fertilizer application according to the soil and climatic situation to enhance fertilizer use efficiency. For maintaing good soil physical condition and improving soil chemical properties we also need to add some organic mannure or compost or crop residues as organic matter. Biofertilizer application can also be done in the fields. But it should be crop specific and micro organisms must be alive at the time of application. Biofertilizers reduces N and P requirement of crops through fixing these nutrients from atomsphere to the soil and these microbes also improve soil physical properties. So, following these techniques we can preserve or enhance soil fertility.
As to feed expanding population we can't control exports of nutrients from soil even it will increase day by day addition of fertilizer to soil in appropriate quantity is necessary along with biofertilizers. Biofertilizer is not source of fertilizer it is for to increase its availablity and improving fertility status of soil
Sagar Maitra Ahmed Hamdan Lafta Ali Mohamed
To my mind, we need to follow all the possible practices that nutrient reserves of the soil are maintained. In other words, we need to maintain health of the soil. Most important aspect of soil health is soil organic matter content. If we are able to follow all those management practices which do not lead to loss of soil organic matter, I believe 50% of the job is done. Majority of nutrients such as nitrogen are preserved in the soil as soil organic matter. Nutrients like P and K need to returned to the soil as fertilizers to maintain the soil reserves. To maintain soil organic matter in the soil, we need to follow practices such as using integrated nutrient management based on organic manures and inorganic fertilizers, returning crop residues to the soil, practising minimum tillage (because tillage is one of the main culprits for loss of soil organic matter), and avoid indiscriminate use of fertilizers, particularly N. When fertilizer N is applied more than required, it leads to loss of soil organic matter and soil health. Practices such as site-specific nutrient management or any other algorithm to apply fertilizers as per need of the crop can be very helpful. Major aim should be not to apply fertilizers more than required to achieve optimum yield levels.
We need to increase biodiversity above ground first with a crop rotation system which includes also grazing livestock species (chickens, pigs, ewes, cows and more if available) and perennial plant species (trees, shrubs, perennial herbaceous species). Crop residues are managed at the farm (even better left on the field for animals to eat). When this is happening the diversity of life in the soil will increase too and these organisms (mainly decomposers) will regenerate soil fertility and contribute to the health of livestock and crops. Biochar added to the soil may amplify and expand microbial diversity a step further for its amending characteristics and richness in pure carbon which is attractive to microbes' settlement.
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