Sweetclover for soil improvement

АУДИТОРНАЯ РАБОТА

XIV. Проверка домашнего задания № 2.

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1. We know two main groups of pastures: natural and culti­vated ones. 2. Mitrog-siious fertilizers are believed to be beneficial for all pasture plant species. 3. Good grazing programme is the only way of pasture improvement. 4, Green succulent feed provided by pastures is of higher quality than hay, as it is richer in protein and vitamins. 5. Drills used for seeding pasture glasses are similar to the ones used for seeding cereals. 6. Pasture grasses and legumes having small seeds, the seedbed they require should be rather compact. 7. Farmers prefer to grow mixtures of grasses and legumes for they are more productive and mutually beneficial. 8. Permanent pastured are Known to be seeded, with such crops as barley, oats, ryegra, and some others. 9. The main thing to be considered while choos­ing the seeding mixture is the purpose for which it will be used. 10. Grasses and legumes grown or cultivated pas­tures are to provide more feed of better quality than the plants of native pastures.

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Sweetclover is considered to be one of the best le­gumes for soil improvement. The heavy, deeply penetrating and widely branching tap root tends to open up the subsoil (подпочва). Subsoil minerals not available to pla its with shallow root systems are brought to the sur­face, and when the sweetclover plants decay, the nutrients contained in these minerals are made available for other

crops. The decay of plowed under sweetclover resuts in a marked improvement of aeration, drainago and the general physical condition of the soil.

Best results are usually obtained when sweetclover is rot plowed under until the plants are 6 to 12 inches tall in spring of the second year. At this time the plants already contain most of the accumulated nitrogen and it is. still sufficiently early to plant corn or somo other culti­vated crop.

The fertilizer value of sweetclover plowed under in the fall of the first year is nearly the same as that plo­wed in spring of the second year. But fall plowing seldom kills the sweetclover plants and they are likely to come 1 up the following spring as weeds in the succeeding crop.' It is primarily for this reason that late*fall plowing is not recommended.'

1. Why isn't it recommended to plow sweetclover under in the fall?

2. How does the tap root of sweetclover influence the soil?

3. What are the advantages of plowing sweetclover under in spring?

4. What is the result of sweetclover decay?

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