Sunday, July 23, 2017

Soil erodability. Soil condition is the key to understand.

Friability of soil refers to its crumbly texture, which is somewhere between sand and clay, not so fine and grainy like sand, or so thick and mushy like clay.A handful of friable soil when pressed hard, should form a lump,but the lump can be easily disintegrated.
Friable soil also will drain water very well, but also retain moisture like a wrung out sponge.Soil which is friable, is usually rich in carbon, minerals and organic http://matter. It will have sufficient porosity to allow oxygen to reach the roots.
The need for friable soil:
Plants grown in friable soil will be healthier, will have lush foliage, strong root systems and resistant to diseases and pests. Friable soil has tons of micro-organisms which will keep replenishing the fertility over time.
How to make clay soil friable :
Mix dried and powdered clay soil with equal volumes of coarse river sand and matured compost to retain its texture, keep mulching it with dry leaves, wood chips etc and maintain its moisture.Friable soil will not get hardened in the sun or become a slush in the rain ,the advantage being it also require less watering than clay.

Soil erodibility (click here) is an estimate of the ability of soils to resist erosion, based on the physical characteristics of each soil. Texture is the principal characteristic affecting erodibility, but structure, organic matter and permeability also contribute. Generally, soils with faster infiltration rates, higher levels of organic matter and improved soil structure have a greater resistance to erosion. Sand, sandy loam and loam-textured soils tend to be less erodible than silt, very fine sand and certain clay-textured soils.
Tillage and cropping practices that reduce soil organic matter levels, cause poor soil structure, or result in soil compaction, contribute to increases in soil erodibility. As an example, compacted subsurface soil layers can decrease infiltration and increase runoff. The formation of a soil crust, which tends to "seal" the surface, also decreases infiltration. On some sites, a soil crust might decrease the amount of soil loss from raindrop impact and splash; however, a corresponding increase in the amount of runoff water can contribute to more serious erosion problems....

Erosion is more than a loss of soil, it is a loss of crops, cash to pay the bills, but, also releases whatever tropospheric gases were trapped there. There are several types of erosion, none are good news and this is among the worst, called gully erosion.

...A soil’s physical condition — its degree of compaction, capacity for water storage and ease of drainage — is also critical to soil and plant health. Good soil tilth promotes rainfall infiltration, thereby reducing runoff and allowing moisture to be stored for later plant use. It also encourages proper root development....

...Among the important chemical determinants of a soil’s health are its pH, salt content and levels of available nutrients. Low quantities of nutrients, high levels of such toxic elements as aluminum and high concentrations of salts can adversely affect the growth of your crops. Healthy soils have adequate — but not excessive — nutrients. Excessive available nitrogen can make plants more attractive or susceptible to insects, and overabundant nitrogen and phosphorus can pollute surface and groundwater. Well-decomposed organic matter helps healthy soils hold onto calcium, magnesium and potassium, keeping these nutrients in the plants’ root zone.

The biological, physical and chemical aspects of soils all interact with and affect one another. For example, if your soil is very compact, it will have few large pores and thus will be less hospitable to such organisms as springtails, mites and earthworms. In addition, its lower levels of oxygen may influence both the forms of nutrients that are present and their availability; under anaerobic conditions, for instance, significant quantities of nitrate may be converted to gaseous nitrogen and lost to the atmosphere....