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71.
There is lack of information available concerning the effect of humic substances (HS) applied via fertigation on plant growth in sandy soils. Therefore, a field experiment was carried out at El‐Saff district (20 km southwest of Cairo), Egypt, to investigate the role of HS fertigation on water retention of a sandy soil, yield and quality of broccoli (Broccoli oleracea L.) as well as on soil nutrient concentration retained after harvest. The experiment consisted of six fertigation treatments (50%, 75%, and 100% of the recommended NPK‐fertilizer rate for broccoli combined with and without HS application at 120 L ha–1) in a complete randomized block design with three replicates. Humic substances affected spatial water distribution and improved water retention in the root zone. Furthermore, application of HS increased total marketable yield and head diameter of broccoli as well as quality parameters (i.e., total soluble solids, protein, and vitamin C). Higher nutrient concentrations were found in the broccoli heads and concentrations of plant‐available nutrients in soil after harvesting were also higher, indicating an improvement in soil fertility. In conclusion, HS fertigation can be judged as an interesting option to improve soil water and nutrient status leading to better plant growth. 相似文献
72.
73.
Dry forests represent the most endangered ecosystem in tropical regions and continue to be one of the most sought after environments for human colonization, development and production. In spite of this, dry forests are one of the least well studied tropical habitats. This special issue is dedicated to reviewing much of the information that exists about tropical dry forest in the Americas. The introduction summarizes the articles presented herein, highlighting management strategies that are suggested throughout the special issue that may be useful for conserving tropical dry forest environments. 相似文献
74.
Weizhen Wang Linan He Zhuzhu Zhang Wenzhi Li Jia Chen Tingting Chen Youhua Long 《Pest management science》2023,79(7):2493-2502
75.
新世纪人才的竞争和挑战,对艺术设计职业教育提出了前所未有的新要求,要使艺术设计专业教育与时代同步,转变教育观念,准确专业定位势在必行,优化课程体系,培养创新人才,是艺术设计专业生存和发展的基础和前题。 相似文献
76.
77.
隧洞内衬钢板灌胶加固技术是在钢筋混凝土隧洞内壁通过植锚栓的方式安装薄钢板,而后在钢板与混凝土接触面之间灌注结构胶,使钢板与混凝土共同受力,满足钢筋混凝土隧洞结构加固的需要。在灌注结构胶的过程中,由于外部灌注压力的作用,薄钢板抗外压失稳问题将受到特别的关注。通过具体工程实例,详细介绍了薄钢板抗外压稳定计算的几种方法。 相似文献
78.
潜土逆旋旋耕机刀片运动及功耗分析 总被引：1，自引：0，他引：1
针对目前我国耕地普遍存在的犁底层问题,推荐应用潜土逆旋旋耕机,以打破犁底层、加深耕作层。借助建立数学模型分析逆旋刀的运动情况,阐述其优势;借助半经验公式分析潜土逆旋的功率消耗,并对影响旋耕机功耗的因素进行说明,以期为设计合理的潜土逆旋旋耕机提供理论支持。 相似文献
79.
S.K. Jalota K.B. Singh R.K. Gupta Anil Sood S. Panigrahy 《Agricultural Water Management》2009,96(7):1096-1104
Individual effect of different field scale management interventions for water saving in rice viz. changing date of transplanting, cultivar and irrigation schedule on yield, water saving and water productivity is well documented in the literature. However, little is known about their integrated effect. To study that, field experimentation and modeling approach was used. Field experiments were conducted for 2 years (2006 and 2007) at Punjab Agricultural University Farm, Ludhiana on a deep alluvial loamy sand Typic Ustipsamment soils developed under hyper-thermic regime. Treatments included three dates of transplanting (25 May, 10 June and 25 June), two cultivars (PR 118 inbred and RH 257 hybrid) and two irrigation schedules (2-days drainage period and at soil water suction of 16 kPa). The model used was CropSyst, which has already been calibrated for growth (periodic biomass and LAI) of rice and soil water content in two independent experiments. The main findings of the field and simulation studies conducted are compared to any individual, integrated management of transplanting date, cultivar and irrigation, sustained yield (6.3-7.5 t ha−1) and saved substantial amount of water in rice. For example, with two management interventions, i.e. shifting of transplanting date to lower evaporative demand (from 5 May to 25 June) concomitant with growing of short duration hybrid variety (90 days from transplanting to harvest), the total real water saving (wet saving) through reduction in evapotranspiration (ET) was 140 mm, which was almost double than managing the single, i.e. 66 mm by shifting transplanting or 71 mm by growing short duration hybrid variety. Shifting the transplanting date saved water through reduction in soil water evaporation component while growing of short duration variety through reduction in both evaporation and transpiration components of water balance. Managing irrigation water schedule based on soil water suction of 16 kPa at 15-20 cm soil depth, compared to 2-day drainage, did not save water in real (wet saving), however, it resulted into apparent water saving (dry saving). The real crop water productivity (marketable yield/ET) was more by 17% in 25th June transplanted rice than 25th May, 23% in short duration variety than long and 2% in irrigation treatment of 16 kPa soil water suction than 2-days drainage. The corresponding values for the apparent crop water productivity (marketable yield/irrigation water applied) were 16, 20 and 50%, respectively. Pooled experimental data of 2 years showed that with managing irrigation scheduling based on soil water suction of 16 kPa at 15-20 cm soil depth, though 700 mm irrigation water was saved but the associated yield was reduced by 277 kg ha−1. 相似文献
80.