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.     

新型植物源复合长效杀虫剂质量评价及其防虫效果

黄帚橐吾和铁棒锤是优质的生物农药资源植物,为了开拓其开发应用前景,本研究通过质量稳定性、室内杀虫活性和小区防效试验,研究了黄帚橐吾提取物和铁棒锤生物碱复合长效杀虫剂的特性和防效。室内杀虫活性和稳定性试验结果表明,此新型植物源复合长效杀虫剂贮存稳定性强,极端环境对其外观和防效的影响小;杀虫效果好,浓度大于0.1%时,1龄棉铃虫幼虫的校正虫口减退率均在85%以上;起效快,用药3 d后校正虫口减退率可达到80%以上;持效期长,用药30 d后,校正虫口减退率仍可达60%左右。小区防效试验结果表明,其对蚜虫、棉铃虫低龄幼虫和马铃薯地下害虫的防治效果分别大于78.05%、75.50%、84.27%,均比其单成分制剂的防治效果高15%以上,且差异显著(P0.05),与相应常用化学农药的防治效果相当。但其持效期长,用药25 d后,对靶标害虫的防治效果仍在80%左右,与对照化学农药和其单成分制剂之间存在显著性差异(P0.05)。本研究结果为资源植物黄帚橐吾和铁棒锤开发提供了依据,为黄帚橐吾提取物和铁棒锤生物碱复合长效杀虫剂的产业化开发应用奠定了理论和技术基础。     

旱作玉米提高降水利用率的覆膜模式研究

通过对旱作玉米几种不同覆膜栽培模式降水利用率、玉米整个生育期的土壤水分监测、生育时期观测、经济性状及产量分析证明,旱作玉米双垄面全膜覆盖集雨沟播技术是一项充分接纳和利用天然降水、最大限度保蓄土壤水分、显著提高降水利用率、提早成熟、增产效果明显、经济效益显著的旱作玉米栽培模式。     

旱地微垄地膜覆盖沟播栽培对土壤水分和胡麻产量的影响

春夏干旱是榆中县旱作区影响胡麻产量的主要限制因素,为了减少土壤水分的无效蒸发、提高土壤含水量、改善胡麻生长环境和提高胡麻产量,开展了旱地微垄地膜覆盖沟播栽培对土壤水分和胡麻产量的试验研究。结果表明,旱地胡麻微垄地膜覆盖沟播栽培减少了胡麻生长期间土壤水分的无效蒸发,胡麻生长期平均土壤含水量提高,胡麻的出苗率提高,胡麻有效分枝数、全株蒴果数、单蒴果粒数、千粒重等经济性状明显改善;旱地胡麻微垄地膜覆盖沟播栽培比露地栽培增产634.2kg/hm2,产值提高4 439.4元/hm2,纯收入增加3 149.4元/hm2。     

种植密度对全膜双垄沟播玉米籽粒灌浆及产量的影响

以‘金凯2号’玉米为材料,研究了6种植密度对全膜双垄沟播玉米籽粒灌浆进程及产量的影响.试验设36 000(JK-A)、42 000(JK-B)、48 000(JK-C)、54 000(JK-D)、60 000(JK-E)、66 000(JK-F)株/hm26个播种密度处理.结果表明:适当增加种植密度可提高全膜双垄沟播玉米单位面积的产量.全膜双垄沟播玉米籽粒干物质积累过程呈"S"型曲线,可用Logistic模型进行模拟,相关系数达0.99以上.种植密度对全膜双垄沟播玉米单粒质量的影响主要是渐增持续期、最大灌浆速率、平均灌浆速率、缓增期灌浆速率和快增期灌浆速率所致,而灌浆持续期对其影响较小.     

黄帚橐吾提取物对保护地辣椒4种病原真菌的抑制活性及其病害防效

针对保护地辣椒多发、危害严重、防治困难的4种真菌病害,开发高效安全的生物农药新资源。通过菌丝生长速率法、孢子萌发法、微量稀释法、种子萌发和温室盆栽防效等试验,研究了黄帚橐吾有机溶剂提取物对保护地辣椒4种病原真菌的抑制活性及其所引发病害的防控效果以及对被保护植物的安全性。结果表明,黄帚橐吾有机溶剂提取物对灰葡萄孢(Botrytis cinerea)、尖孢镰刀菌(Fusarium oxysporum)、茄病镰刀菌(Fusarium solani)和辣椒疫霉(Phytophthora capsici)均有显著的抑制活性,抑制活性强度与其浓度呈正相关,对各病原菌菌丝生长抑制率的EC₅₀分别为11.93、51.25、19.93、13.84 g·L^-1, 对其孢子萌发抑制率的EC₅₀分别为15.05、55.26、57.86、16.50 g·L^-1,最小抑菌浓度为0.83~1.75 g·L^-1,最小杀菌浓度为2.50~11.67 g·L^-1。对4种病原真菌引发的辣椒灰霉病、枯萎病、根腐病和疫病防治效果较好,100倍稀释液的预防效果均可达75%以上,治疗效果也可达70%左右,与相应常用化学农药防效相当。但是其对辣椒种子萌发和幼苗生长有一定的抑制作用,浓度大于20.00 g·L^-1时,种子萌发抑制率大于52.27%,幼苗株高、根长和生物量均与对照之间存在显著性差异(P<0.05)。由此证明黄帚橐吾有机溶剂提取物能有效防控保护地辣椒多发性真菌病害的危害,是一种广谱生物杀菌剂优质资源,合理应用将具有良好的开发前景。     

不同覆盖方式对高原夏季露地松花菜产量、品质和土壤养分的影响

为探明不同覆盖方式对高原夏季露地松花菜产量、品质和土壤养分的影响,通过田间试验,采用地膜和秸秆覆盖(T1)、秸秆行间覆盖(T2)、秸秆全覆盖(T3)、露地无覆盖(CK1)和传统地膜覆盖(CK2)5种覆盖栽培方式,测定分析松花菜的产量、品质、矿物质元素含量、全生育期灌水量、灌水利用效率和土壤养分含量。结果表明:地表覆盖可以降低松花菜全生育期灌水量,其中T1处理产量和灌水利用效率均高于其他处理,较CK1、CK2节水29.0%、7.3%,增产68.9%、4.7%,灌水利用效率提高6.12、1.22百分点。T1处理花球的可溶性糖、维生素C含量均高于其他处理,且硝酸盐含量最低;各处理间可溶性蛋白含量无显著差异。与CK1、CK2相比,T1、T2和T3处理均可以提高花球矿物质元素含量,以T3处理效果最为显著。T1处理土壤有机质、全磷含量较CK1高29.6%、108.4%,全氮、全钾、土壤钙、镁和锰元素含量与CK1无显著差异;T1处理土壤有机质、全氮、全磷和土壤锰元素含量较CK2高14.7%、80.0%、52.0%和105.3%,全钾、土壤钙、镁元素含量与CK2无显著差异。综合分析表明,地膜+秸秆处理具有保墒增产、提高松花菜品质和改善土壤环境的效果,有效实现农作物秸秆的循环利用,避免了当地秸秆焚烧所带来的环境问题,可以促进该地区农业可持续发展。     

兰州地区旱作玉米轮作蔬菜引进筛选试验研究

针对兰州旱作玉米长期连作导致病虫害加重、减产问题突出,本研究旨在以轮作倒茬作物筛选为研究对象,建立合理轮作倒茬制度。引进不同种类、品种的蔬菜作物,试验研究不同播期,不同种植方式,筛选出适宜种植、经济效益高的蔬菜。结果表明:筛选出了西葫芦、娃娃菜、甘蓝、花椰菜等蔬菜。调整好播期,做好病虫害防治,协调好地膜集雨和集流窖补灌的关系,就可以保证蔬菜出苗率和生长期对水分的需求。在兰州半干旱山区种植蔬菜是可行的,具有很高的经济效益,是种植小麦和玉米产值的3~10倍。     

高效环保地膜多年应用对青花菜生长发育的影响

为了减少普通地膜连年使用造成的农田白色污染,为蔬菜生产选择高效环保地膜提供参考,以"耐寒优秀"青花菜为试材,研究高效环保地膜连续使用多年对青花菜生长发育的影响。结果表明:高效环保地膜连续使用3~4年,青花菜产量略有减少,但差异不显著;青花菜生长发育与对照普通黑色地膜和银灰色地膜2个处理没有明显差异;土壤容重有所降低;除草效果好于对照地膜,且回收容易,不易撕裂,没有残留,可以作为普通地膜的替代品。     

Effect of rainfall concentration with different ridge widths on winter wheat production under semiarid climate

Ridge and furrow rainfall concentration (RC) system has gradually been popularized to increase water availability to crops for improving and stabilizing agricultural production in the semiarid area of northwest China. The system is comprised of two elements: the plastic-covered ridge serves as rainfall harvesting zones and the furrow serves as planting zones. To make this system more perfect for alleviating drought stress in semiarid region, it is necessary to test optimum planting systems. A field experiment was conducted from 2007 to 2010 to evaluate the effects of RC planting on soil moisture, wheat yield and water use efficiency (WUE) under different ridge widths. Four planting systems were designed (RC₄₀: 40 cm ridge with 60 cm furrow width, RC₆₀: 60 cm ridge with 60 cm furrow width, RC₈₀: 80 cm ridge with 60 cm furrow width, and CF: conventional flat without ridging). The results showed that RC planting can significantly increase soil moisture in 0–200 cm during the growing seasons of winter wheat. The rainfall-harvesting effect increased with ridge width increasing. Winter wheat yield and WUE was significantly higher under RC₆₀ than under CF by 405.1 kg ha⁻¹ and 2.39 kg mm⁻¹ ha⁻¹, respectively, on average across the three experimental years (P < 0.05). The above findings indicate that RC₆₀ can benefit winter wheat cropping for higher yield through improving soil moisture. It could be concluded that the RC planting system with 60 cm ridge and furrow width will offer a sound opportunity for sustainable farming in semiarid dryland agricultural area.