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美国加州果农喜欢用河水取代井水进行农田灌溉,但河水的含盐量低,渗透速度慢,多年用河水灌溉,致使果树生长势逐渐衰退,如对胡桃树的影响尤为突出。作者对衰退果园和葡萄园的观察表明,衰退问题就在于灌溉水中含钙量低,由此造成钙从土壤中被淋溶掉。衰退树是从地下根开始。经对土壤进行常碎、耙、犁会使树木和葡萄根部出现不少弊端。根不断死亡,新根不断接替。钙对于根的生长和更新是必不可少的。含钙量在140ppm 的灌溉水发根旺盛,而含钙量只有12ppm 的灌溉水则没有发根。如果灌溉水中含盐总量和含钙量低,土壤中的钙会因用低钙量的水灌溉
California, California, like to replace the use of well water to farmland irrigation, but the low salinity of the river water, slow infiltration, years of irrigation with water, resulting in declining fruit trees growing potential, such as the impact on the pecan tree is particularly prominent. The authors’ observations of the declining orchards and vineyards show that the problem with the recession is the low calcium content in the irrigation water, which results in the leaching of calcium from the soil. Decay trees start from the underground roots. After the soil is often broken, rakes, plow trees and grapes will make root defects. Roots are constantly dying, new roots continue to succeed. Calcium is essential for root growth and renewal. Irrigating water with 140 ppm calcium developed strong roots, whereas irrigation water with only 12 ppm calcium did not. If the amount of salt in the irrigation water is low and the amount of calcium is low, the calcium in the soil will be irrigated with low calcium