Soil hardening refers to Soil surface composition damaged under the action of external,Resulting in soil dispersion and dry by the phenomenon of cohesion, is a kind of problem frequently crops up on agricultural production.
Soil aggregate structure is an important indicator of soil fertility, if damaged the soil aggregate structiure will decrease the soil water retention; nutrient preserving capability of soil and permeability of the soil,which makes soil hardened.
Organic matter content is an important indicator of soil fertility and aggregate structure, the reduce of organic matter caused soil hardening.
Long-term single use of chemical fertilizers, humus can not be added in time, not only will cause soil hardened, may also make soil crack. Chemical Fertilizers cause soil hardened is that plants only need cation or anion elements in chemical fertilizer, plants unilaterally absorbs the needed ions makes soil acidification or salinization.
Soil organic matter is an important part of soil aggregate structure, the decomposition of soil organic matter is realized by microbial activity. After applying excess nitrogen to the soil,if the nitrogen in microoraganism added 1 part, corresponding consumption 25 part of carbon elements, the consumed carbon is derived from soil organic matter, makes organic mater content decreased then affect the activity of the microorganism,thus, affect soil aggregate struction leads to soil hardened.
The cationic ions in the soil are mainly calcium and magnesium in 2 valence,if applying excess phosphate fertilizer to the soil,phosphate ions combine with the cations such as calcium and magnesium in the soil to form the insoluble phosphate, not only waste of phosphate fertilizer,but also damage soil aggregate structure,makes soil hardened.
If applying excess potassium fertilizer to the soil, the potassium ions substitution in the potassium fertilizer is particularly strong, will replace the polyvalent cations which formed the soil aggregate structure,and destroy the key bridge action in soil aggregate structure, however, the monovalent potassium ions do not have the key bridge action,it will makes soil hardened.
The dangers of soil hardening and why
In the case of soil hardening, the activity of the root system decreased due to the lack of oxygen, can't normal growth,the plant root cells was weakened, however,the nitrogen and other nutrients were present in the ionic state,need consume the energy of the cell metabolism when plant absorb the nutrients,but weakened respiration makes lack of energy supply,and affect the nutrient uptake.
Soil hardening can also lead to deficiency symptoms. Deficiency symptoms sometimes is not the lack of such elements in the soil,just because the decline of root absorption ability caused by a series of problems such as soil hardening;soil pH is not appropriate;or imbalance of soil water supply.
Break the principle of soil hardening
The application of organic fertilizers or microbial fertilizers into the soil will gradually restore the beneficial microbial communities in the soil. The secretions of microorganisms can dissolve the phosphate in the soil and release the phosphorus. At the same time, the potassium and trace element cations are released,restore the Soil aggregate structure in the form of key bridge to eliminate soil hardening.