格网式垄作及其效益研究

格网式垄作是群众在实践经验基础上总结出的一种保土耕作方法，与横坡垄作相比较，可减少坡地径流６３％～６７％，减少土壤冲刷６８％～７３％，增产４．０％～７．７％。该法主要适用于沙土、壤土等入渗性能较好的土壤。

Discowry of Cosmic Dust in Gold Deposits in Northwestern Sichuan and Its Significance

In recent years, a considerable amount of microscopic spherules have been found in concentrates recovered from some stratabound gold deposits occurring in Middle-Upper Triassic turbidite series in northwestern Sichuan. Study indicates that these spherules are cosmic dust. It is the first time that cosmic dust of extraterrestrial origin has been found in hydrothermal gold deposits in China.The spherules are steel-grey in colour and show metallic luster. Their grain size is commonly less than 100 μm. According to their composition, they belong to chromium-rich iron cosmic dust. The spherules have complex and diverse microscopic structures and textures, i.e. they show a very distinct Widmanstaten structure.The variation of cosmic dust content in gold deposits exhibits a positive correlation with the mineralization intensities and hydrothermal alteration. Such a relation indicates that the ore sub- stances may transport not only mechanically but also may chemically in hydrothermal solutions.

早膜玉米、米麦间作在风蚀耕地上应用的试验研究

在吉林省西部风蚀耕地上的试验结果表明，采用提早覆－膜栽培玉米和玉米小麦间作两种耕作措施，可分别使玉米年产提高１６．２％～２１．２％和１４．４％，并增收部分小麦，每公顷可分别增加收入１８７．７元和２９８．５元，早膜玉米还具有提高地温和土壤含水率的作用，玉米小麦间作可增加地面粗糙度和提高起沙风速，两种耕作措施都可有效地减轻土壤风蚀，是吉林省西部风蚀耕地两项较好的保土种植技术，应积极推广。