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91.
Lincoln Zotarelli Johannes M. Scholberg Rafael Muñoz-Carpena 《Agricultural Water Management》2009,96(1):23-34
Florida is the largest producer of fresh-market tomatoes in the United States. Production areas are typically intensively managed with high inputs of fertilizer and irrigation. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on yield, irrigation water use efficiency (iWUE) and root distribution of tomato cultivated in a plastic mulched/drip irrigated production systems. Experimental treatments included three irrigation scheduling regimes and three N-rates (176, 220 and 230 kg ha−1). Irrigation treatments included were: (1) SUR (surface drip irrigation) both irrigation and fertigation line placed right underneath the plastic mulch; (2) SDI (subsurface drip irrigation) where the irrigation line was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with irrigation and fertigation lines placed as in SUR and irrigation being applied once a day. Except for the “TIME” treatment all irrigation treatments were controlled by soil moisture sensor (SMS)-based irrigation set at 10% volumetric water content which was allotted five irrigation windows daily and bypassed events if the soil water content exceeded the established threshold. Average marketable fruit yields were 28, 56 and 79 Mg ha−1 for years 1-3, respectively. The SUR treatment required 15-51% less irrigation water when compared to TIME treatments, while the reductions in irrigation water use for SDI were 7-29%. Tomato yield was 11-80% higher for the SUR and SDI treatments than TIME where as N-rate did not affect yield. Root concentration was greatest in the vicinity of the irrigation and fertigation drip lines for all irrigation treatments. At the beginning of reproductive phase about 70-75% of the total root length density (RLD) was concentrated in the 0-15 cm soil layer while 15-20% of the roots were found in the 15-30 cm layer. Corresponding RLD distribution values during the reproductive phase were 68% and 22%, respectively. Root distribution in the soil profile thus appears to be mainly driven by development stage, soil moisture and nutrient availability. It is concluded that use of SDI and SMS-based systems consistently increased tomato yields while greatly improving irrigation water use efficiency and thereby reduced both irrigation water use and potential N leaching. 相似文献
92.
Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates 总被引:4,自引:0,他引:4
Mahdi Gheysari Seyed Majid Mirlatifi Mehdi Homaee Gerrit Hoogenboom 《Agricultural Water Management》2009,96(6):946-954
Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO3) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO3-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha−1), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO3-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO3-N leaching out of the 60-cm soil layer was 8.43 kg N ha−1, for the 142 kg N ha−1 and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO3 concentration at the 60 cm depth was 46 and 138 mg l−1, respectively. Based on our findings, it is possible to control NO3 leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management. 相似文献
93.
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95.
荒漠草原植被覆盖对土壤水分的影响 总被引:2,自引:0,他引:2
以希拉穆仁草原为研究对象,通过对不同植被覆盖下土壤水分进行测定,研究了荒漠草原植被覆盖对土壤水分的影响,结果表明:植被覆盖度与土壤水分之间具有显著的相关关系,尤其是10 cm深度范围内土壤水分随植被盖度呈二次抛物线性趋势增加(R2=0.904 9);由于根系层分布的差异使得土壤剖面不同深度上对这种影响的水分响应不尽相同,灌丛植被覆盖的土壤水分含量在剖面0~40cm范围内明显大于其他植被类型,以坡顶土壤含水量最低;荒漠草原植被覆盖状况变化不仅影响土壤水分含量大小,而且显著影响土壤水分的空间分布,退化较轻的河滩草甸植被有利于维持相对均匀的土壤水分空间分布. 相似文献
96.
李艳辉 《农业机械化与电气化》2009,(1):29-30
介绍蔬菜中有机磷和氨基甲酸酯类农药残留快速检测方法的原理,指出实际检测过程巾易出现的问题,并针对这些问题提出相应的解决措施,总结出检测操作中的几点注意事项,以减小误差、避免失误,提高检测结果的可信度。 相似文献
97.
李玉芹 《农业机械化与电气化》2009,(5):77-79
旱灾是制约辽西地区农业发展的重要因素。针对辽西干旱地区农业生产实际,介绍深松和坐水播种技术及其作用,并通过应用试验以验证其对土壤的保墒增墒效果。试验结果表明,在干旱条件下采用这两种技术可有效改善土壤情况,为种子发芽出苗创造适宜的环境条件。 相似文献
98.
99.
四川盆地丘陵区土壤水分垂直变异特征研究 总被引:1,自引:0,他引:1
根据四川盆地丘陵区重庆市璧山县青杠墒情站点土壤水分每天的动态监测资料,用小波分析的谱相分析方法研究了土壤水分的垂直异质性。结果表明:土壤水分变化是个随机平稳的波动序列;就时间变异来看,其变异有一定的隐周期,大致可分为3~5月的次波动期、7~9月的剧烈波动期、10~2月的相对稳定期。就土壤的垂向变化来看,站点的0~10 cm的变异高于10~20、20~40 cm层变异;各层变异之间存在一定的因果关系,可用互谱密度系数表示,但受降水、蒸发、作物利用等多种因素的制约,并未表现出完全的同步响应关系。 相似文献
100.
已有的农业干旱研究中,土壤墒情的模拟与干旱程度的动态评估常常是独立进行的,二者并没有统一起来。基于此,建立了田间土壤水分平衡模型,通过作物生育期内的土壤水分模拟农业干旱过程。为了将土壤墒情模拟与农业干旱的动态评估统一起来,引入了阶段性的作物水分生产函数,通过干旱缺水对农业产量影响的定量分析,反推得出作物不同生育阶段土壤水分状况对应的干旱程度和缺水权重,从而将土壤墒情模拟与农业干旱评估结合起来,达到农业干旱动态模拟与评估的目的,为从土壤墒情状况实时动态评估农业干旱程度提供了一种便捷可行的方法。最后将提出的模型方法结合某灌区进行了应用,效果较好。 相似文献