What is Soil Conservation?
Soil conservation in a broad sense is the placement of each plot of land in a method of use that is in accordance with the capabilities of the land and treating it according to the conditions necessary so that soil damage does not occur. In a narrow sense, soil conservation is defined as an effort to prevent soil damage by erosion and repair soil damaged by erosion.
Soil conservation is carried out to regulate drainage and prevent erosion, especially in sloping areas. Poor drainage will interfere with nutrient availability and root development. Meanwhile, erosion causes the topsoil to be degraded so that it is poor in nutrients and gives rise to subsoil to the surface. Some of the conservation measures are the creation of contour terraces, individual terraces, contour fortifications, rorak, and ditches (drainage system).
In general, soil conservation occurs in various places which significantly affects the ratio of the length of the slope of the land caused by water until the soil shrinks. Then there are several things that need to be considered in water conservation in the context of controlling erosion where the slope of the soil which has been determined in percent and the length of the slope of the soil is called the cropping system.
What Are the Effects of Erosion on Soil Fertility?
In our homeland, especially on sloped lands, the effects of erosion can be identified by the characteristics that are stated as follows:
The characteristics put forward on lands that have been affected by erosion are:
- The occurrence of washing away soil particles,
- Changes in soil structure,
- Decreased infiltaration and holding capacity, and
- change in soil profile.
(a) Soil Particle Washing
As it has been explained that erosion is caused by the movement of water, namely in areas with high rainfall, including the detachment process or the release of soil particles from the fiber, due to the impact power of raindrops with considerable kinetic energy, and the transportation or washing process. namely by the occurrence of uncontrolled run off.
(b) Changes in Soil Structure
The washing away of soil particles such as organic matter and soil colloids caused by erosion will greatly affect the soil structure which means that the shape of the soil structure will be bad.
(c) Decrease in Infiltration and Storage Capacity
Damage to the soil structure due to erosion can cause most of the soil pores to be closed by fine soil grains (particles) and thus the porosity decreases and due to closed soil pores, the infiltration power is also decreased and the surface water flow rate will be heavy. and able to perform surface soil erosion.
(d) Change of Soil Profile
As soil particles are washed away, on the upper slopes, for example, that are not bare (still covered with protective plants, the possibility of erosion is very small, while on the middle slope and the foot of the slope where agriculture is carried out the situation will look different where it is
- in the middle of severe erosion, it is possible that the remaining top soil layer will be very thin when it is not fertile, moderate
- on the legs of the slopes where depositions occur, the surface soil layer will be thicker.
- Soil Conservation Methods
The technology applied to each type of land use will determine whether there is a sustainable use and production of a plot of land. Soil and water conservation methods can be divided into three groups, namely:
a. Vegetative method
The vegetative method is a method of managing sloping land using plants as a means of soil conservation (Seloliman, 1997). In addition to preventing or controlling the danger of erosion, this ground cover plant can also function to improve soil structure, add soil organic matter, prevent the process of leaching nutrients and reduce soil temperature fluctuations.
Vegetative methods for soil and water conservation include, among others: cover crop which functions to hold rainwater from hitting the soil surface, increase soil fertility (as green manure), reduce soil erosion by water and maintain soil productivity levels ( Seloliman, 1997).
Planting grass is used almost the same as ground cover, but has other benefits, namely as animal feed and reinforcing terras. The method of planting can be tightly, in rows or according to contours. The use of crop residues for soil conservation can be in the form of mulch or green manure. With mulch, the leaves or plant stems are spread over the soil surface, while with green manure the plant remains are immersed in the soil (Arsyad, 1989).
The requirements for ground cover crops include:
- Can grow and have many leaves.
- Resistant to pruning.
- Easily propagated by using seeds.
- Capable of suppressing weeds.
- The roots can bind the soil, not a competition for the staple crop.
- Resistant to disease and drought.
- Not spines and twisted branches.
Apart from planting cover crops, other vegetative methods are:
1. Plant alternating lanes, on a slope of 6 - 10% with the aim of:
- Divide the slope so that it becomes shorter.
- Can inhibit or reduce surface runoff.
- Holds soil particles carried away by surface runoff.
The types of alternating stripes are:
- Countur strip cropping is intermittent planting based on contour lines.
- Field strip cropping, used for slopes that are not wavy with paths that can cross contour lines, but plants do not cross contour lines.
- Wind strip cropping, used on flat land or slopes that are not sharp with the plant path perpendicular to the wind, so that sometimes the direction of the groove is in the same direction as the slope.
- Buffer strip cropping, is a row of plants interspersed with grass or legumes as a buffer.
2. Contour planting is carried out on a 15 - 18% slope with the aim of increasing the chance of water infiltration so that run off is reduced.
3. crop rotation.
4. Reforestation or afforestation.
5. Planting the sewer with grass in order to protect the drain from being damaged.
Vegetation group / land use can be seen in table 7 below:
Table 7. Vegetation / land use on oil palm land
|
Vegetation Group /Land use |
Example |
|
Permanent vegetation |
• Dense forest with bushes and litter • Dense grasslands • Perennial crop gardens with good ground cover
vegetation • Dense Imperata grass |
|
Mixed meadow |
• Alfalfa + brome grass • Clover + timothy • Alta fescue + birdsfoot trefoil |
|
Legume with small seeds |
• Clover, Alfalfa • Calopogonium muconoides • Centromesa pubescens |
|
Small grain cereals |
• Rye • Wheat • Barley • Oats • Rye • Wheat • Barley • Oats |
|
The legume has large seeds |
• Soybeans • Peanuts |
|
Annual crops are usually planted in rows |
• Tobacco • Potatoes • Cassava • Corn • Sorghum |
|
Barren land without vegetation cover |
• When cultivating the soil until the plants grow • Open land without vegetation cover |
b. Mechanical method
The mechanical method is a method of managing dry land (overland land) by using physical facilities such as soil and rocks as a means of soil conservation. The goal is to slow down the flow of water on the surface, reduce erosion and accommodate and drain surface water flow (Seloliman, 1997).
Included in the mechanical method for soil and water conservation, including tillage. Soil tillage is any mechanical manipulation of the soil that is necessary to create a favorable soil condition for plant growth. The main purpose of soil cultivation is to prepare a place to grow seeds, create a good root area, bury plant debris and eradicate weeds (Arsyad, 1989).
Technically-mechanical erosion control is an effort to preserve soil to reduce the amount of land lost in agricultural land areas by certain mechanical means. In connection with the mechanical soil improvement efforts being pursued are aimed at slowing down the surface runoff and accommodating and continuing the distribution of surface runoff with non-destructive soil erosion power.
Soil tillage according to the contour is any type of tillage (plowing, hoeing, equalization) following the contour lines to form grooves and pile paths that are in the same direction as the contour and cut the slopes. These soil grooves will inhibit surface water flow and prevent erosion so as to support conservation in dry areas. The main advantage of tillage according to contour is the formation of surface runoff inhibitors that allow water absorption and avoid soil transport. Therefore, in dry climates, contour tillage is also very effective for this conservation.
Making terras is to change the sloping ground surface into multiple levels to reduce the speed of surface flow and to hold and accommodate it so that more water seeps into the soil through the infiltration process (Sarief, 1986). According to Arsyad (1989), making terras works to reduce the length of the slope and hold water, thereby reducing the speed and amount of surface runoff and allowing soil absorption, thereby reducing erosion.
c. Chemical method
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Soil structure stability is one of the soil properties that determines the level of soil sensitivity to erosion. What is meant by chemical methods in erosion prevention efforts, namely by using a soil conditioner or soil stabilizer in terms of improving soil structure so that the soil will remain resistant to erosion (Kartasapoetra and Sutedjo, 1985). Chemicals as soil conditioners have a huge influence on the stability of soil aggregates. The effects are long-term because these compounds are resistant to soil microbes. Soil permeability is enhanced and erosion is reduced. These materials also improve annual plant growth on heavy clay soils (Arsyad, 1989). The use of soil stabilizers for agricultural lands and plantations that have just been opened is actually very necessary considering:
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