碱茅草在甘肃内陆盐渍地草地农业生产中的作用

EFFECTS OF PUCCINELLIA CHINAMPOENSIS ON AGRO-GRASSLAND PRODUCTION IN INLAND SALINE REGIONS OF GANSU PROVINCE

作者在甘肃河西内陆盐渍地种植碱茅草(Puccinellia chinampoensis ohrusi)11046亩,经田间试验、定点研究和室内试验表明;碱茅草种子对硫酸盐的最大耐盐度为3.47%,氯化物1.58%,碳酸盐为1.08%;幼株对硫酸盐忍耐力为2.5%;成株在5.0%以内尚可生长。3年生碱茅草地耕层土壤的脱盐率达到66.0～95.0%(灌溉条件下),在3年内的1536克/m^2的总脱盐量中,碱茅草地上和地下部总吸收盐量占总脱盐量的11.0%,89.0%脱洗的盐量积累于地下水和耕层之下的土壤中。碱茅草地积返盐速度远小于对照裸地,主要是碱茅草良好的郁闭度减少了土壤蒸发,造成上层土壤脱盐。发育良好的碱茅草地,大于0.25mm的水稳性团聚体增加13.4～22.6%,土壤渗透性增加12.5～39.9%,达到了改良利用盐渍土的效果。3年生碱茅草地耕翻后种植春小麦,亩产250～364公斤;甜菜3000公斤,水稻125～410公斤,糜子110公斤,胡麻83公斤的中产水平。为此,建立起盐渍区的草地农业生产系统,并形成盐渍土——碱茅草——草食家畜和盐渍土——碱茅草(3年生)——农作物两条配套生产线,将称谓“癌症”的盐渍土赋予农业生机。

The field, pot, and laboratory experiments showed that the maximum level of toierance of salt, chloride, and carbonate for seed germination of Puccinellia chinampoensis is 3.47%, 1.58%, and 1.08%, respectively。The upper limit of suphate to lerance for seedling and adult plant growth is 2.5%and 5.0%, respectively。After 3 year growth of the grass the content of soluble salt in the soil at ploughing depth was reduced by 66—95% under irrigation, which is eguivalent to 1536 g soluble salt per m^2. Eleven per cent of tolal amount of soluble salts reduced in the soil was absorbed by the above—and under—ground parts of the plants, the remainder was in undergroud water system and in the soil below ploughing depth。The evapotranspiration of P.chinampoensis pasture was significantly lower than that of bare soil, which resulted in slower re—accumulation of salt in the surface soil。The waterstable aggregates (> 0.25mm in diameter) and soil permeability is increased by 13.4—22.6%and 12.5—38.9%, respectively。Thus the soil chdemical and physical property was greatly improved。The yields per mu of different crops growing on this improved soil have been reached the average level of those on the crop land i.e.250—364 kg for sppring wheat, 3000 kg for sugar beet, 125—410 kg for rice, 110 kg for millet, and 83 kg for linseed。It is concluded that establishment of agro— grassland system by introducing P. chdinampoensis is an effective way to improve saline soil and to develop agricultural production in inland saline regions。