潮土区小麦-玉米轮作周期内土壤钾素动态研究 Ⅰ.不施钾条件下土壤钾素动态与垂直变化

STUDIES ON DYNAMICS OF POTASSIUM IN SOIL PROFILE IN WHEAT MAIZE ROTATED CHAO SOIL REGION Ⅰ. THE DYNAMIC AND VERTICAL CHANGE OF POTASSIUM IN SOIL PROFILE WITHOUT POTASH APPLICATION CONDITION

采用大田试验和室内分析的方法，研究了豫北潮土区小麦玉米轮作周期内土壤钾素的动态及垂直变化。结果表明：在不施钾肥条件下，轮作期内土壤钾素消耗量较大，速效钾的大量消耗促进了缓效钾的释放；缓效钾在土壤供钾水平降低时也是作物吸钾的重要来源。土壤钾素的动态变化及其在剖面中的垂直移动，主要受作物吸收、温度、降水及土壤水分运动的影响。作物生育前期以表层钾素供应为主，在需钾高峰期心土和底土供钾也很重要。小麦生育期钾素以向上运移为主，而玉米生育期内钾素以向下淋移较为显著。轮作期土壤钾素的消耗主要是由于作物吸收，也有少量的淋失。在该地区生产中，补施钾肥、增加农家肥和秸秆用量十分必要。

Applying the methods of field trial and indoor chemical analysis, this paper studied the dynamic changes of various forms of potassium in soil profile during a wheat maize rotation in Chao soil of northern Henan Province under conditions of non potash application. The results showed that without potash application, large amount of soil potassium was exhausted, the reduction of soil fast available potassium promoted the release of non exchangeable potassium(slowly released potassium), which is an important source of potassium for crop absorption when the soil potassium supply was poor. The changes of soil potassium in the profile were related to the crop absorption, temperature, rainfall and water movement in the soil body. In the early period of crop growth, the potassium supply in the cultivated horizon (0～20 cm) is most important for crops, and in the peak period to absorb potassium, the potassium supplies in subsoil (20～ 50 cm ) and bottom soil (50～70 cm) were also important. The vertical movement of potassium in soil profile was mainly the upward transportation in the wheat growing period, but in the maize growing period, the downward leaching was evident. The exhaust of soil potassium during the whole rotation period mainly attributed to the crop absorption, and the leaching loss only accounted for a small portion. It is necessary for field production in this region to add potash and increase the use of organic fertilizer and straw.