北疆膜下滴灌棉田生育期土壤水盐的变化特征

针对北疆地区土壤盐化制约农业发展的问题,通过野外实地分层采集土样,分析北疆地区长期膜下滴灌农田种植前后土壤水分和盐分分布特征。统计学分析表明,种植期土壤含水量变异属于中等偏弱变异强度,土壤盐分的变异属于中等偏强变异程度,土壤盐分分布成自上而下先增大再减少的波动趋势。在空间分布上,土壤水分和盐分种植前后存在明显的差异,种植后在浅层土壤水分和盐分的含量成西高东低的变化分布。     

免耕覆盖麦秸土壤中酚酸浓度的变化及酚酸对夏玉米早期生长的影响

室内和田间试验表明:麦秸的水浸提物对玉米的胚芽和胚根的生长有显著影响作用。小麦-玉米轮作区免耕覆盖的土壤中可以检测到4种酚酸:阿魏酸、香草酸、肉桂酸和对羟基苯甲酸,它们在土壤中的平均含量分别为(2.62～4.94)×10-5,(5.72～7.54)×10-5,(3.05～5.38)×10-5和(3.93～5.20)×10-5mol/L。它们在土壤中下降的速度很慢。室内检测阿魏酸、香草酸和对羟基苯甲酸抑制玉米的胚芽和胚根的生长,其抑制根伸长10%的浓度(ED10)分别是1.14,3.57和6.30mmol/L。     

Yield and quality components of silage maize in killed and live cover crop sods

In sloping areas with high precipitation, planting maize into live winter cover crop sods may help to alleviate the environmental problems associated with clean-tillage production systems of maize. The present study evaluates the performance of silage maize (Zea mays L.) under several cultivation methods: CC (conventional cropping system, i.e., maize was sown into the bare, autumn-ploughed soil); LGS/CK (maize was planted into a living Italian ryegrass (Lolium multiflorum Lam.) sod which was subsequently herbicidally killed); and LGS/MR (similar to LGS/CK, but the ryegrass was mechanically regulated). The research was conducted in the midlands of Switzerland on a fertile sandy loam under humid conditions during three cropping seasons. With 110 kg N ha⁻¹ (fertilizer nitrogen plus mineral nitrogen of the soil at maize planting), the CC system was much more productive than were the LGS/CK and LGS/MR systems in terms of dry matter and nitrogen yields of maize. Increasing the nitrogen supply to 250 kg N ha⁻¹ considerably reduced the yield advantage of CC over the LGS/CK and LGS/MR systems, indicating that nitrogen was the most limiting factor for maize yield in the mulch seeding systems. With 250 kg N ha⁻¹, the LGS/CK and LGS/MR systems produced greater total yields of digestible organic matter (maize plus ryegrass) than did the CC system, whereas the total nitrogen yield was similar for all cropping systems. The whole-shoot concentrations of nitrogen were highest under CC, irrespective of the level of nitrogen supply. With 110 kg N ha⁻¹, concentrations of phosphorus and magnesium were clearly higher for the mulch seeding systems. There were only minor differences among the cropping methods in the concentrations of potassium and calcium in the whole shoot. When 250 kg N ha⁻¹ were applied, there were no significant variations among the cropping systems in the concentrations of minerals. Changes in the botanical composition of the cover crop sod and in the time and method of cover crop control may help to reduce the competition for nitrogen between maize and the living mulch.     

不同覆盖方式对植烟土壤有机质及烟叶品质影响的初步研究

为提高烟叶品质,进行了对植烟土壤不同覆盖方式的比较试验,结果表明:高C/N比秸秆与地膜双覆盖能够协调烤烟生长全过程的土壤温度,并且地温日变化幅度小,蓄水保墒作用显著,有机质积累明显,腐殖化作用强,使得烟叶内在化学成分比例更协调,产值高。秸秆单覆盖对土壤性状改良与秸秆和地膜双覆盖相似,烟叶内在化学成分较协调,品质较好,但由于在烤烟生长前期不能提高土壤温度,使得烟叶生长速度较慢,产量下降,产值与地膜单覆盖差异不显著;由于没有新鲜的有机质补充,地膜单覆盖对土壤性状改良不及秸秆单覆盖和秸秆与地膜双覆盖,从而使得烟叶品质较不协调,但产量较高,产值也较高。     

The effect of plastic mulch on the fate of urea-N in rain-fed maize production in a semiarid environment as assessed by 15N-labeling

A better understanding of the fate of fertilizer nitrogen (N) is critical to design appropriate N management strategies in plastic-mulched croplands. We evaluated the effects of plastic mulch on urea-N recovery by crops and loss from soil in furrow-ridge plots, with and without maize (Zea mays L.) cropping, in a semi-arid rain-fed site in China. We applied the same rate of urea-N (281 kg ha⁻¹) to all treatments during the preparation of the furrow-ridges in 2011 and 2012 but ¹⁵N-labeled the urea in 2011 only. We used transparent film to cover all soil surfaces in the mulched treatments and seeded maize in furrows in treatments with crop. In 2011, plastic mulch increased the total N uptake in the aboveground biomass of maize by 53%, whereas it decreased the in-season labeled-N uptake by 19%, compared to non-mulched treatment. At harvest in 2011, in mulched treatments the total labeled-N remaining in the 0−170 cm soil layer was 25% greater whereas unaccounted labeled-N was 69% less, than in non-mulched treatments, regardless of whether maize was cropped. In 2012 the effect of mulch on total maize N uptake was comparable to that in 2011, but the residual soil labeled-N uptake by maize was 63% higher in mulched compared to non-mulched treatment. At harvest in 2012, plastic mulch increased total labeled-N remaining in the 0−170 cm depth in cropped soils and unaccounted labeled-N in non-cropped soils, compared with no mulch. Our results indicate that plastic mulch profoundly changes the fate of urea-N in maize production in cold and dry croplands.     

膜下滴灌棉花植株耗水率与土壤水分的关系

膜下滴灌技术不仅可减少地面水分蒸发 ,还可以避免深层渗漏。为了合理地确定膜下滴灌技术体系 ,以水量平衡原理为基础 ,对轻壤土、中壤土和重壤土进行不同土壤含水率处理 ,试验得出了棉花生育期植株耗水规律 ,以及棉花成铃数与生育期耗水量的对应关系。在不产生深层渗漏的条件下 ,土壤含水率越高 ,棉株耗水越大 ,但成铃数的增加有限。另外 ,观察到膜下滴灌棉花的根系主要吸水层在 60 cm土层深度以内     

旱地玉米双相覆盖技术在太原地区的增产效果与机理

玉米双相覆盖技术在太原生态区增产率为１４．４８％。具有苗期适宜增温促发、中期保墒促长的土壤环境效应。增产机理是：玉米地上部和地下部协调增长，叶面积大，茎秆还原糖贮量多，干物质积累也多；具持续高强度灌浆特性，加快了物质运转速度     

棉花膜下滴灌盐分动态及平衡研究

在南疆气候条件下．研究了膜下滴灌盐分动态变化及平衡．结果表明：在南疆，棉花苗期时，土壤盐分开始分区，盐分在膜间0～40cm强烈聚集，膜下盐分变化不大，而且在覆膜的作用下发生侧向运移，移向膜间，加剧了膜间的盐分累积；棉花生育期结束后．土壤0～60cm盐分都有增加．在膜间0～20cm盐分强烈累积；灌水量为345mm的处理盐分增加明显，积盐率高达．94．5％，其增加的盐分主要来自下边界土壤水分上行所带来的盐分，占盐分增加量的57％．而灌水量505mm处理增加的盐分主要来自灌溉水所携带的盐分，占81％．若不考虑灌溉水的矿化度，膜下滴灌土壤盐分的积盐率只有13．8％。     

秸秆覆盖畦田灌溉水流特性及灌水质量分析

在陕西杨凌张家岗村覆盖玉米秸秆的冬小麦地进行了畦田规格和灌水技术要素对灌水效率和灌溉均匀度影响的田间试验,并SRFR406软件对秸秆覆盖畦灌的水流推进进行了数学模拟.结果表明,给出的地面灌溉模型及软件可较好的模拟秸秆覆盖畦田水流运动.畦田规格与技术要素的选择对灌水效率及灌水均匀度均有影响.在覆盖秸秆畦田以畦长小于50 m,畦宽2～3 m,单宽流量以6～8 L/(m·s),坡度以3‰～5‰为宜.为提高秸秆覆盖灌水效率,应加强耕作管理,消除反坡.     

覆盖免耕夏玉米耗水特性的研究

以无覆盖翻耕、无覆盖铁茬等常规耕作为对照,对覆盖免耕夏玉米的耗水特性进行了研究。结果表明耕作并没有大幅度增加或者减少夏玉米的耗水量,不同耕法夏玉米耗水量差异不大;同翻耕、铁茬等相比,覆盖免耕夏玉米耗水在时间和空间分配上有所改变,即覆盖免耕夏玉米前期耗水少,后期耗水量增加,蒸散量加大,而且覆盖免耕有效地减少土壤棵间蒸发,却增加了作物的蒸腾量,变非生产性耗水为有效耗水,有利于夏玉米产量和水分利用效率的提高