Greenhouse gas implications of water reuse in the Upper Pumpanga River Integrated Irrigation System, Philippines

Enhancing water productivity is often recommended as a “soft option” in addressing the problem of increasing water scarcity. However, improving water productivity, particularly through water reuse, incurs additional investment and may result in increased greenhouse gas (GHG) emissions. In this study, we analysed the water productivity and GHG implications of water reuse through pumping groundwater and creek water, and compare this with gravity-fed canal irrigation in the Upper Pampanga River Integrated Irrigation System (UPRIIS) in the Philippines.Water productivity indicators show that water reuse contributes significantly to water productivity. For example, water productivity with respect to gross inflow (WP_gross) with water reuse (0.19 kg grain/m³) is 21% higher than without water reuse (0.15 kg grain/m³). However, there is a tradeoff between increasing water productivity and water reuse as water reuse increases GHG emissions. The estimated GHG emission from water reuse (pumping irrigation) is 1.47 times higher than without water reuse (gravity-fed canal irrigation). Given increasing concerns about climate change and the need to reduce carbon emissions, we recommend that a higher priority be given to water reuse only in areas where water scarcity is a serious issue.     

PG99S智能型喷灌机的调试及维护

在蔬菜、花卉的工厂化育苗生产中,准确控制肥水的浓度和喷洒的均匀性显得尤为重要,而喷灌设备作为智能型连栋育苗温室的主要浇灌设备,被广泛应用于现代化育苗温室中。该设备自动作业,水量控制精准。本文就PG99S型智能喷灌机介绍其调试方法和故障维修。     

磷肥减施对集约化露天菜地周年磷损失削减效果评价

集约化菜地因高量施肥以及大水漫灌导致其在农田磷污染排放中的占比最高,目前已成为种植业磷损失的优先阻控对象。在定量评估菜地周年磷损失量的基础上,明确蔬菜合理的磷肥投入阈值范围,通过源头控制菜地磷的迁移、流失,对于有效降低中国农业面源污染造成的环境压力具有重要意义。以太湖流域露天菜地为研究对象,设置农民习惯施磷(对照)和减量施磷处理(减施20%、30%、50%和100%),通过为期一年的蔬菜轮作试验,明确土壤磷素环境阈值及磷素周年径流流失特征。结果表明,菜地磷环境阈值为78.9 mg·kg^-1,所有处理土壤表层有效磷(Olsen-P)含量均超过环境阈值。随施磷量的减少,菜地总磷(TP)径流损失浓度降低,并主要以可溶性磷(DP)流失形态为主,DP/TP比例为50.1%～63.1%。磷径流损失负荷呈现出明显的季节性特征,夏秋季磷素流失量为1.93～3.26 kg·hm^-2(以P计),占全年磷素流失通量的59.2%～63.2%。结构方程模型结果表明,当季施磷量直接且极显著影响TP流失浓度,并且TP流失浓度对TP流失负荷存在极显著的正向影响,影响系数为0...     

Response of five tobacco cultivars to sodium phosphate and ammonium polyphosphate

Abstract

Three greenhouse experiments were conducted to compare the response of five tobacco (Nicotiana tabacum L.) cultivars to different levels of NaH₂PO₄ and ammonium polyphosphate (APP) in nutrient media by measuring tissue content of selected nutrient elements (P, Na, K, Ca and Mg). Plants were grown in sand cultures fertilized with nutrient solutions in two experiments and a soil‐sand mix fertilized with solid materials in a third experiment. Plant P and Na content increased as the concentrations of these elements increased in nutrient solution. Plant K content was not generally affected by treatments. Magnesium was reduced in flue‐cured and cigar‐filler tobaccos but was not changed in cigar‐wrapper and Turkish types by increasing amounts of NaH₂PO₄. All of the cultivars responded similarly to NaH₂PO₄ with respect to plant Ca. High levels of P in the nutrient media were consistently related to low levels of Ca in plant tissue.     

Mineralization of Organic Nitrogen in Soils with Contrasting Fertility Was Regulated Differently by Addition of Biochar and Animal Manures

ABSTRACT

How to restore the soil fertility and productivity in a damaged and then reclaimed area with extremely low fertility is a big concern worldwide. To explore the method of soil restoration in the coal mining subsidence area, the effects of biochar application coupled with organic fertilizer (animal manures) on the process of organic nitrogen (N) mineralization were studied in a 149 days leaching experiment. Biochar were applied (wt/wt) at the rates of 0%, 1%, and 3%. Two organic fertilizers with different C/N ratio (chicken and sheep manures) were applied at the rate of 200 mg N·kg^?1 soil. A vegetable soil with high-fertility was used as the comparison. The results showed that when treated with chicken manure, the reclaimed soil had 11.13% lower mineralization potential and 20.00% lower inorganic nitrogen production from mineralization than the vegetable soil. Compared with the non-biochar treatment, biochar at both application rates decreased N leaching in chicken manure-treated reclaimed soil, i.e., by 21.49% (1% biochar) and 28.31% (3% biochar), respectively, whereas only high rate of biochar application decreased N leaching in chicken manure-treated vegetable soil by 8.10%. However, N leaching in sheep manure-treated reclaimed soil was unaffected by the biochar application. Thus, the effect of the biochar on the organic nitrogen mineralization was affected by both soil and organic fertilizer type.     

多孔毛管温室冠层空间热风增温实验

为研究微孔散热条件下,多孔毛管沿程温度分布规律、温室冠层以下空间的垂直温度梯度及其与主要影响因素之间的关系,构建了多孔毛管温室空间热风增温实验系统。对多孔毛管进行保温围护,以毛管进口温度、进风压力、出风孔径等为实验参数,采集毛管前端孔口、中间孔口与末端孔口围护空间内温度数据,分析其在毛管沿程方向上和垂直空间内的分布规律。实验结果表明,毛管沿程出风孔口围护空间温升略有降低;垂直空间内温升呈先上升后下降的驼峰状变化趋势。不同进口温度、进风压力条件下,构建的热风增温系统可以使围护空间内距地面800～1 200 mm高度空间内的温度升高2.5～6.2℃。     

蔬菜自动移栽机对置秧盘交替自动取投苗机构研究

针对现有蔬菜自动移栽机茎秆夹持式和钵体顶出式取苗方式的缺点,基于顶出-夹取结合式取苗方式,设计了一种适用于对称布置可弯曲秧盘的交替式取投苗机构。阐述了该机构工作原理、关键点运动轨迹和结构组成。分析了关键因素对秧苗夹持点运动轨迹的影响方式并优选了取值：驱动曲柄转速10r/min,取投苗摇杆长度为 309mm,驱动气缸伸出速度25mm/s,0.8s内完成拔苗,伸出时刻为提前0.4s。该参数组合下秧苗夹持点在拔苗阶段最大横向位移9.6mm,累计横向位移0mm,理论提升高度44mm,满足取投苗作业理论要求。以苗龄45d的辣椒秧苗为作业对象,进行了栽植频率70~120株/(min·行)的取投苗性能试验,试验结果表明,该交替取投苗机构在栽植频率100株/(min·行)时可实现取苗成功率93%,投苗成功率95%,总体成功率88%,满足取投苗作业要求,验证了该取投苗机构的可行性。     

对蜂蜜中主要抗褐变因子的探讨

选用ＡＧ５０Ｗ－Ｘ８阳离子交换树脂，并以批处理的方式，成功地将蜂蜜中的肽类物质与其它组合得到了分离。抗褐变实验结果清楚地表明，蜂蜜中的肽类成分完全没有抑制褐变的活性。这与以前的报道截然不同。     

The Box Plot Experiment in Grossbeeren after eight rotations: nitrogen,carbon and energy balances

The Box Plot Experiment in Grossbeeren was set up in 1972 to investigate the efficiency of diverse fertilization strategies within an irrigated vegetable crop rotation system for three different soils. Here, we report on the long-term effects on nitrogen, carbon and energy balances of applying various organic amendments and different amounts of mineral N fertilizer to soils. Fertile soils (sandy loam and clayey silt) were characterized by higher yield and N removal potential by plants, higher acceptable N input amounts, and a higher proportion of total N input recovered by soil N storage and N uptake by plants. After 40 years, organic carbon equilibrium in the soil has not been reached. Rates of change of organic carbon stocks are still affected by the different organic matter levels at the beginning of the experiment. An increasing net N supply increased and organic C input decreased net C gains. Because of the manifold possibilities of producing energy from current or former agricultural land, energetic evaluation of land use needs to become more complex if direct comparisons are to be made. Including the energy contents of organic amendments and soil organic matter in the energy balances would be a first step in this direction.     

蔬菜的硝酸盐污染及防控措施

由于不合理的种植手段,造成了蔬菜的硝酸盐污染,影响蔬菜的品质,威胁人类的身体健康和生命安全。通过重视施用有机肥、合理施用氮肥、注意施肥时期和施肥种类、在不同季节使用正确栽培设施、使用硝化抑制剂(氮肥增效剂)等技术手段,可以明显减少硝酸盐在蔬菜中的残留,对发展绿色无公害蔬菜生产和提高人民生活水平有着十分重要的意义。