By Sharon Chebet
Compaction is something you can never eliminate in your farm, but you can certainly reduce it. Soil is made up of particles of sand, silt and clay. Healthy soil also contains organic matter. Another very important property of soil is that; it has tiny air spaces between its particles called pores that can be visually observed. At least 50 percent of the total volume of a healthy soil should be made up of pore spaces that allow exchange of air and water.
When subjected to pressure, soil gets compacted. When dry soil is compacted, it becomes so tightly packed and does not allow aeration and when water-saturated soil is compacted, it loses moisture, and water can no longer penetrate through.
How do I know my soil is compacted?
You can test how compacted your soil is by pushing a spade in, screwdriver or even digging. If this proves difficult, then you likely have compacted soil.
There are other ways that compaction may manifest in your farm: for example, absence of oxygen will lead to having unpleasant smell in some spots and crops wilting even with water supply.
What causes soil compaction?
A shift towards intensive agriculture to meet the ever-increasing demand for food is a major cause of compaction. This is characterized by mechanization, especially, use of tractors.
Monoculture also causes soil compaction. Most farmers grow one type of crop season after season. The importance of crop diversification is that different crops have different rooting depths and absorb nutrients from the soil differently. This means that, if you have intercropped a variety of plants in your farm, some roots will be going deeper than others hence loosening the deeper layers of the soil.
Thirdly, intensive grazing contributes to compaction through trampling. The more the animals trample on the soil, the more it compacts.
Other causes of compaction include poor land preparation such as planting on soils with low organic matter, ploughing the same depth every season and tilling at the wrong moisture content. A quick way to determine whether the moisture content of soil is good for tilling, is to take a handful of soil and squeeze it into a ball in your hand. The moisture content is good for tilling if slight pressure from your fingertips causes the ball to crumble. It is advisable to till at least three days after the onset of rain. This will have allowed the excess water to be absorbed into the soil.
Why compaction is bad for your soil.
Compaction causes crops to experience nutrient deficiency, water stress and restriction of root penetration. This results to iron chlorosis (yellowing of leaves).
Because the water cannot go through the hard pans in the soil, then it runs off eroding the top fertile soil. As a result, the crops get very little nutrients and cannot yield much.
How can a farmer remedy soil compaction?
- Balancing calcium and magnesium levels in the soil
The amount of calcium and magnesium minerals in the soil determines how easily it absorbs water and its stickiness.High magnesium percentage and low calcium percentage increases the probability of having compacted areas in your farm. To determine the level of these minerals, conduct a soil test. The solution is to ensure that your soil has sufficient organic matter. The more organic matter you have in your soil, the more your soil will be strengthened hence taking in and holding more water and nutrients. You can increase the amount of organic matter in your soil by adding compost, aged animal manures, green manures (cover crops) and by mulching.
- Controlling your soil PH
Soil pH is a measure of acidity or alkalinity of soil. The optimal PH value is 5.5 to 6.5 close to neutral. Liming and use of gypsum will tackle soil pH as well as balancing the calcium-magnesium ratio. Lime, which is calcium carbonate, is used to increase soil pH whereas gypsum (calcium sulfate dihydrate) will remedy sodic soil (soil with excess sodium) without affecting the pH of the soil.
The reason for controlling soil pH is to provide a conducive environment for soil microorganisms to grow. Microorganisms are responsible for loosening the compacted soil and decomposition of organic matter which contributes to good soil structure.
- Tilling to different depths
Vary your tillage depth. For example, if your tillage depth is 20 centimetres frequently, what happens is, you end up having a hard pan at 20 centimetres. The top of the soil may give a good impression but on digging deeper below 20 centimetres, you will discover a hard pan. The best solution is, on small scale, hand tilling your soil using a jembe or the fork jembe and ox plough. On large scale, tractors are unavoidable. However, ensure that your service provider embraces the following: reducing tire pressure to minimal allowable pressures and using larger diameter tires to increase length of footprint to minimize compaction.
By Sharon Chebet
Compaction is something you can never eliminate in your farm, but you can certainly reduce it. Soil is made up of particles of sand, silt and clay. Healthy soil also contains organic matter. Another very important property of soil is that; it has tiny air spaces between its particles called pores that can be visually observed. At least 50 percent of the total volume of a healthy soil should be made up of pore spaces that allow exchange of air and water.
When subjected to pressure, soil gets compacted. When dry soil is compacted, it becomes so tightly packed and does not allow aeration and when water-saturated soil is compacted, it loses moisture, and water can no longer penetrate through.
How do I know my soil is compacted?
You can test how compacted your soil is by pushing a spade in, screwdriver or even digging. If this proves difficult, then you likely have compacted soil.
There are other ways that compaction may manifest in your farm: for example, absence of oxygen will lead to having unpleasant smell in some spots and crops wilting even with water supply.
What causes soil compaction?
A shift towards intensive agriculture to meet the ever-increasing demand for food is a major cause of compaction. This is characterized by mechanization, especially, use of tractors.
Monoculture also causes soil compaction. Most farmers grow one type of crop season after season. The importance of crop diversification is that different crops have different rooting depths and absorb nutrients from the soil differently. This means that, if you have intercropped a variety of plants in your farm, some roots will be going deeper than others hence loosening the deeper layers of the soil.
Thirdly, intensive grazing contributes to compaction through trampling. The more the animals trample on the soil, the more it compacts.
Other causes of compaction include poor land preparation such as planting on soils with low organic matter, ploughing the same depth every season and tilling at the wrong moisture content. A quick way to determine whether the moisture content of soil is good for tilling, is to take a handful of soil and squeeze it into a ball in your hand. The moisture content is good for tilling if slight pressure from your fingertips causes the ball to crumble. It is advisable to till at least three days after the onset of rain. This will have allowed the excess water to be absorbed into the soil.
Why compaction is bad for your soil.
Compaction causes crops to experience nutrient deficiency, water stress and restriction of root penetration. This results to iron chlorosis (yellowing of leaves).
Because the water cannot go through the hard pans in the soil, then it runs off eroding the top fertile soil. As a result, the crops get very little nutrients and cannot yield much.
How can a farmer remedy soil compaction?
- Balancing calcium and magnesium levels in the soil
The amount of calcium and magnesium minerals in the soil determines how easily it absorbs water and its stickiness.High magnesium percentage and low calcium percentage increases the probability of having compacted areas in your farm. To determine the level of these minerals, conduct a soil test. The solution is to ensure that your soil has sufficient organic matter. The more organic matter you have in your soil, the more your soil will be strengthened hence taking in and holding more water and nutrients. You can increase the amount of organic matter in your soil by adding compost, aged animal manures, green manures (cover crops) and by mulching.
- Controlling your soil PH
Soil pH is a measure of acidity or alkalinity of soil. The optimal PH value is 5.5 to 6.5 close to neutral. Liming and use of gypsum will tackle soil pH as well as balancing the calcium-magnesium ratio. Lime, which is calcium carbonate, is used to increase soil pH whereas gypsum (calcium sulfate dihydrate) will remedy sodic soil (soil with excess sodium) without affecting the pH of the soil.
The reason for controlling soil pH is to provide a conducive environment for soil microorganisms to grow. Microorganisms are responsible for loosening the compacted soil and decomposition of organic matter which contributes to good soil structure.
- Tilling to different depths
Vary your tillage depth. For example, if your tillage depth is 20 centimetres frequently, what happens is, you end up having a hard pan at 20 centimetres. The top of the soil may give a good impression but on digging deeper below 20 centimetres, you will discover a hard pan. The best solution is, on small scale, hand tilling your soil using a jembe or the fork jembe and ox plough. On large scale, tractors are unavoidable. However, ensure that your service provider embraces the following: reducing tire pressure to minimal allowable pressures and using larger diameter tires to increase length of footprint to minimize compaction.