Agronomical measures for controlling soil and water erosion

 Agronomic Measures

1. It is the practices of growing vegetation

2. It is done on mild sloppy land

3. It is used to reduce runoff, enhance infiltration, and dissipate the impact of raindrops

due to cover, dissipate the erosive power of erosive agents, and control wind

erosion and water erosion.

4. In the soil loss equation, agronomical measure reduces the value of C and P from 1 to 0.2

and 0.5 respectively.

Following are the types of agronomical measures for controlling soil and water erosion,

Contouring

Contour farming

The objective of contour cultivation/farming

 To reduce the sheet and rill erosion

 To reduce the sediment transport and other solids and nutrients

 To enhance the infiltration rate.

Contour farming involves ploughing, planting, and weeding along the contour, i.e, across the slope rather than up and down. Contour lines are lines that run across a (hill) slope such that the line stays at the same height and does not run uphill or downhill. As contour lines travel across a hillside, they will be close together on the steeper parts of the hill and further apart on the gentle parts of the slope.

Experiments show that contour farming alone can reduce soil erosion by as much as 50% on moderate slopes. However, for slopes steeper than 10%, other measures should be combined with contour farming to enhance its effectiveness.

Criteria of contour farming

 Minimum row grade: should not be water ponding

 Maximum row grade: maximum 10 %, 25 % is permissible for 150 feet distance of outlet.

 Minimum ridge height :

when row spacing more than 10 inches: minimum ridge height should be 2 inches when row spacing less than 10 inches: the minimum ridge height should be 1 inch for close-growing crops

 Stable outlets: safely dispose of excess water, the grade should not exceed 0.2 % Caution: If contour lines are incorrectly established, then they can actually increase the risk of erosion.

Contour farming is farming with row patterns that run nearly level around the hill not up and down the hill. Generally, as the rain falls, a lot of runoff is generated which generally leads to soil erosion on its way downward. This removes the top fertile soil along with soil nutrients and plant seeds thus leading to scanty and uneven growth of the crop. To avoid this simple practice of farming is done across the slope so that there are no steep slopes on the field. Ridges and furrows thus formed act as continuous barriers to the free movement of water downwards thus provides more infiltration time. Hence, the removal of soil along with nutrients is checked to a greater extent leading to increment in soil fertility and crop yield.

Limitation of contour farming

 It gives a better result on a relatively uniform slope but impracticable on irregular topography.

 Grassed waterways should be employed with contour farming When and where to use contour farming

 used in gentle slope not much more effective on a steep slope with high rainfall

Strip cropping

 Strip cropping/farming is the growing of crops in narrow, systematic strips or bands to reduce soil erosion from wind and water. Strip cropping helps to stop soil erosion by creating natural dams for water, helping to preserve the strength of the soil.

 Certain layers of plants will absorb minerals and water from the soil more effectively than others.

 Row crops (maincrop) are grown alternate with other protective crops (Mainly grass or legumes) in the same field. The strips with the greatest surface vegetative cover capture soil eroded from upslope areas.

 To improve erosion control, the strips are usually planted on the contour in a rotation that shifts crops annually from one strip to the next.

 The most effective strip-cropping rotations include perennial grasses and legumes that alternate with grain and row crops. In arid and semiarid regions, strips may be placed perpendicular to the prevailing wind direction for wind erosion control.

Tillage Practices

 Tillage is the mechanical manipulation of soil for weed control, seedbed preparation, and a good porous root environment. Tillage operations can be divided into two categories: primary and secondary tillage. Primary tillage can include the use of the mouldboard plough, chisel plough, or disk plough. It is often the most intensive form of tillage. It inverts the soil over the entire field. Primary tillage is the first soil tillage after the last harvest to break soil surface into clods. Subsequent tillage operations used to prepare the seedbed are referred to as secondary tillage. These operations can include the use of tandem or off-set disks, field cultivators, harrows, and packers to pulverize, repack and/ or smoothen soil surface. Operations that disturb the soil during seeding, management, or harvesting of the crop are referred to as tertiary tillage.

 Objectives of tillage

Vary with soil, crop, and climatic conditions and are also influenced by the socio-economic status of the farming community.

1. The basic objective is to obtained good soil tilth for crop growth and yield or preparation of seedbed with optimum tilth

2. Weed control

3. Reduction of mechanical impedance to root growth

4. Soil incorporation of organic/inorganic matter

5. Modification of infiltration characteristics

 Types of tillage

Depending upon the kind, amount, and sequence of soil disturbance during seedbed preparation can be grouped into two classes

1. Conventional tillage

2. Conservation tillage

1. Conventional tillage is the tillage system that has been developed traditionally and followed by the farming community. It involves maximum primary and secondary tillage operations.

2. Less intensive than conventional tillage. The most important component of conservation tillage is the retention of crop residues on the soil surface (at least 30%). The conservation technology information center in Indiana, USA has divided conservation

tillage into four systems

a) No-tillage (also called no-till, zero tillage)

b) Reduced tillage: less intense than conventional tillage by eliminating one or more tillage operations from a conventional tillage program. Primary and secondary tillage are combined together

c) Stubble tillage: Any tillage operation that retains crop residues on the soil surface. Also known as mulch farming, mulch tillage, or plough less farming.

Basically designed to control wind erosion but it controls water erosion also.

d) Ridge tillage: a method of land preparation whereby the topsoil is scraped and concentrate in a defined region to deliberately raise the seedbed above the natural terrain. On sloping planting (<7%) ridge planting is effective.

Advantages of conservation tillage

 Protect land against erosion

 Increased soil organic matter

 Increase activity of soil macro and microfauna

 Improve soil structure

 Lower cost of cultivation

No-tillage

It is a method of planting crops that involves no seedbed preparation, other than the opening of soil for placing seed at the intended depth. In a no-till system, herbicide replace tillage for wee control, and a favorable environment for seeds is provided by the decaying residue of the soil surface, which act as a mulch to conserve soil and moisture and improve soil productivity.

Advantages of no-tillage

 Saving in time, energy, and labor and cost-effective

 Favors timely sowing of crops

 Increase in soil organic matter content

 Moisture conservation

 Soil conservation by reducing wind and water erosion

Mulching and soil management practices

 The word mulch has probably derived from the German word “molsch” which means soft to decay, which apparently referred to the gardener’s use of straw and leaves as a spread over the ground as mulch.

 Mulch is simply a protective layer of any type of material that is spread at the surface or vertically in the soil to assist conservation of soil, water, and productivity or Applying plant residue or other suitable material produced offsite, to the land surface.

 Mulching reduces the deterioration of soil by way of preventing runoff and soil loss, minimizes weed infestation, and checks water evaporation. Thus, it facilitates more retention of soil moisture and helps in the control of temperature fluctuations improves physical, chemical, and biological properties of soil, as it adds nutrients to the soil and ultimately enhances the growth and yield of crops.

Types of mulches:

1. Organic mulches: Materials used for mulches are natural substances such as bark, municipal tree waste, cocoa bean hulls, leaf mulch, grass clippings, composted animal manure, and newspaper. They get decomposed easily and need frequent replacements.

2. Inorganic mulches: Plastic film (polyethylene), petroleum products, Stone, rubber. These materials are used for perennial crops.

3. Vertical mulch: Vertical mulch is a technique that consists of digging suitable trenches across the slope and thus making more surface area available for water absorption. The open trenches are likely to get silted in a short period.

4. Soil mulch: Soil mulches are created by intensively hoeing the soil surface. According to proponents, dust mulching breaks the soil capillarity, reducing the evaporative loss of soil moisture. If the surface of the soil is loosened, it acts as mulch for reducing evaporation. This loose surface of the soil is called soil mulch or dust mulch.

Benefits of Organic Mulching

 Mulch reflects a lot of the sun that otherwise heats the soil. This keeps the soil cooler and helps prevent evaporation. This is especially important in hot, dry climates. When the soil is covered in mulch, weeds do not grow under it as they do not get the light they need to grow. Mulches prevent soil erosion, as the wind or running water does not directly come in its contact and does not blow or wash it away. Mulches spread over the soil, slow down rainwater run-off, and increase the amount of water that soaks into the soil. And more water in the soil means more water for the crops. Organic mulches also improve the condition of the soil. As these mulches slowly decompose, they provide organic matter which helps keep the soil loose. These organic matters become food for the beneficial earthworms and other soil microorganisms in the soil and create a very good porous soil. This improves root growth, increases the infiltration of water, and also improves the water-holding capacity of the soil. Decaying organic matter also becomes a source of plant nutrients. Maintains a more even soil temperature. Keeps feet clean, allowing access to field even when damp

Advantages of Inorganic Mulching

 Moisture conservation, Soil Conservation, Soil Temperature, Soil Solarisation (With Transparent Plastic Mulch Controls disease pest), Weed Control.

Cover crops

 Cover crops are noncash crops grown for benefits such as protect the soil from erosion, weed management, soil quality, nitrogen fixation, pest and disease control, biodiversity, etc., rather than for harvest and sale (cash crops). Cover cropping is now a widespread technique due to its many, considerable benefits.

 Cover crops contribute to soil quality improvement principally through their decomposition by soil microbes. The products of decomposition, while generally adding to the soil organic matter (SOM) reservoir, benefit the soil in two specific ways, i.e., through soil physical conditioning and through fertility building. The degree of enrichment depends on the quantity and quality of cover-crop biomass.

 Growing cover crops can improve soil tilth by decreasing erosion, increasing infiltration, and adding organic residues to the soil. These benefits are achieved because cover crops are often grown only during seasons when the soil is especially susceptible to erosion, although in orchards and vineyards the cover crops are frequently grown year-round. The leaves and stems of the cover crop intercept rainfall and dissipate its energy, while roots bind the soil and hold it in place. The amount of benefit from cover crops depends on the above- and belowground biomass and rooting structure of the plant being grown and the length of time before the soil is prepared for the next crop.

Crop rotation

Crop rotation is defined as a “system of growing different kinds of crops in recurrent succession on the same land”

Benefits of crop rotation

 Rotating different crops year after year adds various economic and environmental benefits.

 Crop rotation is helpful in long-term soil and farm management.

 Rotating different crops can break pest cycles and add extra nutrients to the soil.

 Crop rotations build soil fertility, preserve the environment, control weeds, diseases, and insects, and add to crop and market diversity

 The use of long-term diverse rotations helps in improving grain yield as well.

Crop rotations are not universally common, rather they depend on different environmental and soil conditions. The rice-wheat crop rotation occupies about 18 million hectare area in Asia, of which 75% are in the Indo-Gangetic Plains of India (10 million ha)

Crop rotation in relation to conservation agriculture

 Crop rotation is an essential component of conservation agriculture systems, where a sequence of crops is rotated every season with grasses or legumes to achieve a diverse system to enhance soil biodiversity and physical structure. The diversity of the root system that promotes a diverse microbial community is reflected in the development of soil aggregates. Crop rotation coupled with a no-tillage system can contribute significantly to soil aggregation and water conservation, especially in arid and semiarid climate regions within intensified agriculture cropping systems. Soil aggregate formation, governed by biotic and abiotic processes, plays a significant role in nutrient cycling, SOC storage, and providing a growth environment for the root system. These functions are influenced by crop rotation as a driver for facilitating the biochemical and physical conditions that are responsible for forming and binding soil particles.