山东滨海盐渍棉田盐分和养分特征及对棉花出苗的影响

 在黄河三角洲6个县区随机选择318块盐渍棉田，对0～20 cm土层盐分、有机质和主要养分含量分析表明，轻度（含盐量<2.5 g·kg^-1）、中度（2.5～4.49 g·kg^-1）和重度（>4.5 g·kg^-1）盐碱地所占的比例分别为44.3%、40.6%和15.1%。中度盐碱地N、P、K含量皆中等偏下，轻度盐碱地则是钾含量偏低；种植年限短的重度盐碱地有机质含量很低，碱解氮和有效磷含量严重不足，但含钾量高；种植年限较长的重度盐碱地有机质、碱解氮和有效磷的含量中等，但速效钾较低。滨海盐碱棉田土壤含盐量（y）和土壤溶液（水：土=5：1）电导率（x）回归方程为y=3.4058x + 0.1427（n=27，R²=0.9964^**）。当土壤含盐2 g·kg^-1 以下时，棉花基本能正常出苗、成苗；当含盐2～3 g·kg^-1时，只有60％～78%的种子可以出苗，45％～55%的种子能够成苗；含盐超过 4 g·kg^-1时，出苗率40%左右，成苗率不足30%。根据滨海盐碱地的盐分和养分特征，采取合理的成苗技术和施肥技术是实现棉花高产的保证。

Characteristics of Salinity and Fertility in Coastal Saline Cotton Fields in Shandong and Their Effects on Cotton Emergence

Soil samples (0～20 cm) from 318 saline cotton fields randomly selected in the Yellow River Delta were used to study the characteristics of salinity,contents of organic matter and major nutrients.The results showed that,of the total 318 saline fields tested,the lightly salty (LS) fields (salt content <2.5 g·kg-1),moderately salty (MS) fields (2.5～4.49 g·kg-1) and severely salty(SS)fields (>4.50 g·kg-1) accounted for 44.3%,40.6% and 15.1%,respectively.The levels of N,P,K in MS fields were moderate,but K level in LS fields was low.The contents of organic matter,N and P were deficient,but K content was abundant in SS fields where cotton had been planted shorter than 5 years.In contrast,the contents of organic matter,N and P were moderate,but K content was relatively low in SS fields where cotton had been planted longer than 5 years.Regression analysis showed a significant linear correlation between soil salt content (y) and soil solution conductivity (x) at 25°С (y=3.4058x+ 0.1427,n=27,R2=0.9964**).Normal emergence and stand establishment rates were obtained when soil salinity was lower than 2 g·kg-1.Rates of emergence and stand establishment were reduced to 60%～78% and 45%～55%, respectively,when salinity was 2～3 g·kg-1.The emergence and stand establishment rates were only about 40% and < 30%,respectively,in saline fields with salinity higher than 4 g·kg-1.Reasonable agronomic measures for stand establishment and chemical fertilization should be taken according to the characteristics of salinity and fertility,to improve cotton productivity in saline fields.