Soil behavior, the adequate amount of fertilizer and the simple analysing method of nitrate nitrogen for green asparagus production by whole season cropping system

Concerning the semi-forcing production of green asparagus by a whole season cropping system, the following were found: 1) The plow layer soil and subsoil were in the cultivation area. However, excessive fertilizer applications and current annual applications of organic matters derived from livestock excrements resulted in marked deposits of phosphate and calcium and an imbalanced base composition. 2) A comparison of fields of a high yield with those of a low one revealed that the soils of the former were high in humus content at 10-15% and mellow with specific gravities ranging 0.8-1.0. Effects of application s of organic matters and plowing deep manifested in the former. 3) Although the dry matter ratio and the content of inorganic components in young stems varied by grade (thickness), they did not vary within a grade by the amount of nitrogen application. 4) The adequate amount of nitrogen application was 40 kg as 10 t of a compost made from rice hull and cattle excrement was applied to per 10 a. 5) Care should be not taken to allow nutrient deficiency during the period from immediately after stem standing to abundant growth of stems and leaves, because an, intensive absorption of inorganic nutrients from the soil took place during that period. 6) Asparagus annually absorbs about 23 kg of nitrogen, 8 kg of phosphate, and 24 kg of potassium per 10a in the semi-forcing culture by whole season cropping system. 7) Basal dressing with controlled-release fertilizers for the. whole requirements, which eliminate intermediate top dressings for labor saving, increased yield by more than 10%, saved nitrogen supply, and resulted in less deposit of bases. 8) The proper concentration of inorganic nitrogen in soil was 5-25 mg per 100 g of dry soil for stable production. Also, the concentration corresponded to 0.2-0.8 mS/cm in red soils and yellow ones, which are representative soils in Nagasaki Prefecture. 9) Most of nitrate nitrogen in soil could be recovered by 30-second shaking mixture of soil and water. 10) The measurement of nitrate ion in aqueous extract of soil with a small reflection photometer could be used for the quick and easy quantification method of nitrate nitrogen.