3-Soil Health

Transcript

Hello friends. Today, we will talk about soil health. We will discuss what is soil health and what is its relationship with soil quality. We will also look at the main components of soil health.

Soil health is something basic that we can feel and understand but it is difficult to measure. Soil health is just like human health but doing an assessment of soil health is very difficult. Soil health depends on soil quality. We cannot directly measure soil quality so we do an indirect assessment of it through soil properties. We do have vast knowledge about soil health but we cannot just summarize it into a simple formulae or indicators like we do for human health.

The best indicator of our soil health and soil quality is our crop yield. As we cannot directly measure the soil quality indicators, we measure the soil properties to get an idea about the soil health. So a straight forward measurement of soil health is not possible that could give us a clear result if the soil is healthy or not.

Soil health works on two important properties: inherent soil properties and dynamic soil properties.

Inherent soil properties include things like with which rock the soil is made of, the time of soil formation and its parent material. It also includes things like the topography of soil, what was the vegetation and how long did it take to be formed.

Now, major soil classifications are described and divided under inherent soil properties. We can check the different types of soil like its parent material and if the soil is acidic or alkaline, productive or unproductive.

Soil health also depends on soil dynamics which includes things like the land use, what was the cropping system, how was cultivation and management done and the decisions. Soil quality depends on the above and they are influenced by soil health, management, cropping system, farming system, temperature, seasonal crops. So their overall management governs to soil health

So the dynamic and inherent properties are the factors that govern soil health. Soil health depends on three properties: physical properties, chemical properties and biological properties.

All these three properties indicate soil quality. Soil’s physical properties function is to support the plant so that it can stand upright and grow. It also controls soil erosion. If the physical condition of soil is good, then soil erosion will be less and if it is bad then the soil will erode with water. The hardness of soil also depends on soil physical properties like if the soil is hard or soft. Soil physical properties also help with water retention and the movement of water within soil profile.

Soil chemical properties function is to retain the nutrients and also how to release them. It also controls soil reactions like EC and pH. Carbon energy storage also depends on soil chemical properties.

Soil biological properties affect weed, pests and diseases and their suppression. The growth of microbial population in the soil like micro-roots and micro root zone depends on biological properties. Organic matter decomposition rate and the N mineralization of soil i.e. nitrification and denitrification is also governed by biological properties.

Now we look at soil physical properties. It includes soil temperature called also soil thermodynamics, soil moisture, bulk density, hardness of soil, soil permeability and soil composition and aggregation.

The soil chemical properties include EC and pH, available nutrients, total nutrients, total organic carbon and available carbon etc.

The biological properties include the growth and population reactions of bacteria, fungi and actinomycetes. It also includes insects and pest related disease and their growth and seeds.

The organic matter decomposition depends on microbial population and bacteria. It will also be according to soil biological properties. It includes the rate of organic matter decomposition if there are more bacteria or actinomycetes or fungi in the soil.

So these were the three soil properties and now we will discuss them further in detail and how management affects them.

We had discussed earlier the relation between residue retention and soil physical properties. We will also talk about soil health under CASI and how soil physical properties are governed.

We will first talk about soil permeability or infiltration. If we practice residue retention and conservation agriculture for a long time, then the soil permeability or infiltration or water soaking capacity increases. This recharges the aquifer and also prevents water logging and crop burn out.

If we do zero tillage and conservation agriculture continuously then the soil aggregation i.e. there is improvement in small lumps of soil. This helps wit overall soil composition and structure.

If we retain residue, then our moisture is conserved and that regulates our temperature. This can moderate temperature by 5 to 6 degrees which is very beneficial during extreme high and low temperatures.

If we practice CASI and retain residue and do zero tillage and crop diversification, then it conserves water as the capacity to retain moisture increases. This is possible because the soil physical properties like soil structure temperature and bulk density improves and as a result the water retention capacity increases. Also the mulch helps prevent water evaporation.

Now we look into soil biological properties and the enzymes like bacteria, fungi and actinomycetes. If you look at the graph, the population of dehydrogenize activities and enzymes increase. The total microbial carbon and actinomycetes increases. So we can see in the graph that all the three enzymes population increases where residue retention is practiced. But their population falls where there was no residue retention and tilling was practiced. We have 28% growth of bacteria, 68% growth of fungi and 98% growth of actinomycetes where we do zero tillage and residue retention and mulch.

This was all for micro fauna. But the macro fauna population also increases like soil and seed predators and many other beneficial insects. The population of earthworms also increases. So the overall biological properties of soil increases and there is self-tillage in the soil like if the population of earthworm increases then they till the soil on their own and release nutrients.

Now, we discuss soil chemical properties, especially soil organic carbon. This is directly associated with how much organic matter we are providing to the soil like farmyard manure, crop residue or any other plant biomass. So in the graph, we can see that after 5 years of CASI, if we are continuously providing residue of all the three crops then the value increases from 0.45 to 0.9. So the soil surface values doubles.

The benefits of it in soil profile will be less and will only be found in the long run. So this is over all an improvement in soil carbon.

Another thing we notice in the graph is that the amount of available macro nutrients like nitrogen, phosphorus, potassium and Sulphur increases and they are easily available to the plants. Now the availability of micro nutrients like iron, zinc, manganese, boron and other non-essential but important nutrients like silicon also increases and so there is good plant growth.

So if there is overall improvement in physical, biological and chemical properties then we can see in the graph the photosynthesis rate of plants increases. The canopy temperature which is very important in the later stage of plant, if at that time our temperature is maintained then there is good grain filling and grain weight as a result of which we get good production.

Overall if our soil health is good, our soil quality indicators like physical, biological and chemical properties are good then our overall soil and plant and water relation improves and as a result we get good crop and yield.

Now, we will look at the advantages. The soil’s physical, chemical and biological properties are very important for soil health. If we have a problem in one of the properties, then we won’t have good soil.

The soil health improves under CASI as compared to traditional farming as the three chemical, biological and physical properties of soil improves.

If our soil is healthier then we will get good quality yield and we become healthier by eating good quality food.

The soil health and soil quality takes years to improve but if we want to destroy it then we can do that in just one year by adopting wrong practices. It is just like human health where it takes years to keep good health but in just one month we can get any diseases or anything by eating unhealthy things.

If our soil is healthy then our plant will be healthy and it would have better resilience against climatic shocks. This can improve our income and the quality of food we eat and the quality of soil for our future generation will be better.

It is very important to maintain the soil health.

Thank you and hope you enjoyed this chapter.