Some physiological bases of agricultural and gardening practice. Nutrients

you are: Some physiological bases of agricultural and gardening practice

The Diet of crops and separate plants is similar. The the crop if only used concentration is not toxic is more brought certain nutrient, the above, does not influence absorption of other elements, is not so high to cause harmful osmotic effects because of accumulation of salts in soil, and other nutrients do not limit growth. However in process of increase in doses of brought mineral substances strengthening of the growth reached by each additional increase of a dose, decreases. As cost of fertilizers remains to a constant, the further increase of crops by additional increase in doses eventually ceases to justify; during this moment optimum productivity from the point of view of cost of a unit of production is reached.

For achievement of optimum efficiency and economy of fertilizers it is better to bring in regular intervals them during all vegetative period, than to bring all dose for once. In the latter case some elements absorbed by a plant not at once, can be adsorbed clay kolloidami and organic substance of soil and will be consumed by a plant during the vegetative period; however the majority of soils has limited adsorbtsionnuju capacity, and the superfluous quantity of the introduced fertilizer can be washed off to a water mirror, and subsequently - in the rivers and lakes. It causes evtrofikatsiju - the strengthened growth of seaweed and other plants in the lakes which before were pure because of deficiency of nutrients. working out of fertilizers with the limited solubility, such as formaldehyde with the urea, slowly liberating nutrients, has lowered similar losses of mineral elements. This innovation represents, in essence, return to one of desirable properties of some initial organic fertilizers like, for example, bone flour. But modern fertilizers such it is better that the necessary substances in controllable quantity provide and are more accessible to consumers.

The Main nutrients used in agriculture, is a nitrogen, phosphorus and kaly (N, R and. The majority of fertilizers contain these one or more elements, and percentage of nutrients under the law should be specified on packing. So, in fertilizer with a mark 5: 10: 5 5% (from a lump) nitrogen, 10% of oxides of phosphorus and 5% of oxides kalija contain. Most valuably that fertilizer in which contains more nutrients not on a lump, and on price unit, and these substances are in slowly liberated form. Doses of brought fertilizers depend on culture and from natural fertility of soil. Higher maintenance N in comparison with R and To favours to growth of stalks and leaves to the detriment of reproductive activity. Therefore under the cultures which are grown up for the sake of sheet weight, usually introduce fertilizers with higher maintenance of nitrogen, than under other cultures.

Other nutrients (besides N, R and usually do not join in fertilizers as the soil usually contains them in enough. But if deficiency of microcells is found out, it is possible to bring a necessary element in soil. If in soil there are enough nutrients, but they are inaccessible that soil conditions do their insoluble it is possible to change these conditions or to spray leaves the diluted solution of the necessary salt. Leaves are capable to absorb enough salts for satisfaction of the requirements if the corresponding element is necessary only in small quantities.

Improper value rn soils (fig. 14.1) happens One of the main causes of death or bad growth of plants. In most cases difficulties arise at sour soils. Usually agricultural crops start to suffer at rn more low 5,5-6,0, and at rn more low 5,0 are damaged more seriously. A principal cause of damage of plants on soils with strong acidity - the in itself high maintenance of ions N + and superfluous availability of iron (on tropical soils as well aluminium) is frequent not. When because of high acidity these elements in considerable quantities pass in the dissolved condition, they become toxic (fig. 14.1).

At the same time low value rn limits receipt of some elements, for example phosphorus. Usually acidity of soil can be eliminated by addition to exhaust in the form of a carbonate or gidrookisi calcium. Alkaline soils usually meet less often and represent for agriculture a smaller problem, than sour. However high shchelochnost (rn> 8) can do iron and phosphorus rather insoluble and thus to limit growth of plants. Diet normalisation includes finishing rn soils to 6,0-8,0 with the subsequent entering of scarce elements into the quantities equal to their annual carrying out with a crop. The requirement for additional substances can be established by the analysis of soil or leaves or visually on symptoms of deficiency at plants.

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