Effects of Different Gravel Mulched Years on Soil Microbial Flora and Physical and Chemical Properties in Gravelsand Mulched Fields

Soil microbial flora and influencing factors of soil microbes in soil and gravel-sand mixed layer（ SGSML）,roots denseness layer（ RDL）,eluviate layer（ EL） and calcium accumulation layer（ CAL） in gravel-sand mulched fields（ GSMFs） with different gravel mulched years（ 1,6,12,19 and 25 years） were studied. The results showed that in the composition of soil microbes in the GSMFs,the quantity of bacteria was the largest,followed by actinomycetes,while the number of fungi was the smallest. The total quantity of soil microorganisms in the GSMFs dropped rapidly with the increase of soil depth,which was related to the sudden decrease in the quantity of bacteria. The number of microbes in the RDL was larger than that in the SGSML with few roots due to the effects of root distribution. The number of bacteria and actinomycete in the growing season was larger than that in the non-growing season,while the quantity of fungi in the growing season was smaller than that in the non-growing season. The quantity of bacteria and fungi was the largest in the GSMFs which had been mulched with gravel for 6-12 years. With the increase of mulching time,the GSMFs aged gradually,so their quantity reduced gradually. The quantity of actinomycetes was the smallest in the GSMFs which had been mulched with gravel for 6-12 years and increased with the increase of mulching time. The number of soil microbes in the GSMFs had a good correlation with soil moisture content,p H and mulching time. Soil total carbon content was an important factor restricting the quantity of soil microbes in the GSMFs.

宁夏砂田不同砾石覆盖厚度土壤入渗过程及模型分析

以宁夏中部旱区砂田土壤为研究对象,通过对不同砾石覆盖厚度条件下砂田土壤水分入渗过程进行研究,采用一维垂直定水头入渗法,选取砾石覆盖厚度为影响因子,设置5个覆盖厚度(0,6,9,12,15cm),观测湿润锋运移和入渗量变化规律,比较各处理土壤入渗特征,利用模型拟合土壤入渗过程。结果表明,砾石覆盖提高了土壤水分入渗能力,土壤湿润锋运移距离和入渗量明显增加。与CK相比,砾石覆盖厚度为6,9,12,15cm时的累积入渗量分别增加了4.3%,11.8%,12.8%和17.1%,平均入渗率增加了25.8%,38.7%,50.0%和62.9%;同时砾石覆盖厚度改变了土壤水分入渗曲线,随着砾石覆盖厚度增加,土壤初始入渗率迅速增加,但稳定入渗率增加较为缓慢。与CK相比,砾石覆盖厚度为6,9,12,15cm时的初始入渗速率分别增加了40%,81%,91%和110%;稳定入渗速率分别增加了15.3%,17.9%,20.5%和25.6%。利用3种入渗模型对砂田土壤水分入渗过程进行拟合,结果表明Horton模型拟合效果最好,是分析和预测不同砾石覆盖厚度土壤水分入渗过程的适宜模型。

水肥调控对宁夏旱砂地枣树生长发育的影响

以种植在宁夏中卫市香山干旱山区压砂地的3年生‘同心圆枣’树(行间套种西瓜,每公顷产量12000kg～13500kg)为试材,研究了保水剂+补水补肥对土壤含水量、坐果率、产量、品质、水分利用率和树体营养生长的影响,试验结果表明:每株施30g～60g保水剂,并在枣树生长期补水补肥2次,使整个生育期40cm处土壤含水量绝对值提高了2.14%,单叶面积增加了4.1%～50.5%,叶绿素含量增加了44.9%(与放任生长的树相比),坐果率提高了9.5%～27.8%,单株坐果量提高了29.5%～33.2%,单株产量提高了37.9%～51.1%,平均单果重增加了0.5g～2.1g,水分利用率提高了33.3%～46.7%,果实固酸比增加了23.0%～41.8%、维生素C含量略有增加,新枣头粗度和主干增粗率也略有增加。

提高宁夏旱砂地幼龄枣树坐果率的技术研究

以种植在宁夏中卫市香山干旱山区压砂地的3a生‘同心圆枣’树(行间套种西瓜,产量12 000～13 500kg/hm2)为试材,研究了当年生枣头单纯摘心、‘新枣头+二次枝’双摘心、叶喷赤霉素以及主干环切等措施对幼龄枣树坐果率、坐果量、枣头及二次枝粗度和其它树体生长发育指标的影响。结果表明:盛花期枣头摘心提高坐果率的效果好于初花期或盛花初期;‘新枣头+二次枝保留2～4节’双摘心,或‘新枣头摘心+叶喷20mg/kg赤霉素’,均具有明显的提高坐果率和单株坐果量的效果,但主干环切或‘新枣头摘心+主干环切’或‘新枣头+二次枝’双摘心+主干环切均更能极显著地提高坐果率和坐果量;在花期,‘新枣头+二次枝保留2～4节’双摘心能较明显地提高新枣头和二次枝的粗度。主干环切幼树的主干年增粗率明显小于新枣头摘心或‘新枣头+二次枝’双摘心的树。

旱区压砂地甜瓜水肥最优组合研究

为了研究甜瓜(Cucumis melo L.)节水节肥栽培技术,采用正交试验法,在旱区压砂地上,对膜下滴灌条件下的灌水定额、施肥量和灌水次数3因素进行了最优组合方案比较研究。结果表明,影响甜瓜产量的主要因素是灌水定额,其次是灌水次数和施肥量;方差分析结果表明,试验的最优因素水平组合是灌水定额为37.5 m3/hm2、施肥量为900 kg/hm2、灌水次数为5次。

补施有机肥对砂田辣椒生长及产量的影响

在砂田条件下,研究有机肥施用量对砂田辣椒生长发育及产量的影响.结果表明:随着有机肥施肥量增加,辣椒生育期延长,株高、叶面积、光合速率和蒸腾速率增长,在施肥量为100 kg/666.7 m2时达到最佳;水分利用率在施肥量为50 kg/666.7 m2时达到最大;施肥量为129.5 kg/666.7 m2时产量最高,为1 879 kg/666.7 m2.因此,砂田辣椒补施有机肥适宜用量为100～150 kg/666.7 m2.