Simulating management effects on crop production, tile drainage, and water quality using RZWQM-DSSAT

The objective of this study was to explore if more crop-specific plant growth modules can improve simulations of crop yields, and N in tile flow under different management practices compared with a generic plant growth module. We calibrated and evaluated the Root Zone Water Quality Model (RZWQM) with the Decision Support for Agrotechnology Transfer (DSSAT v3.5) plant growth modules (RZWQM-DSSAT) for simulating tillage (NT — no till, RT — ridge till, CP — chisel plow, and MP — moldboard plow), crop rotation {CC — continuous corn, and CS — corn (Zea mays L.)-soybean [Glycine max (L.) Merr.]}, and nitrogen (N) (SA — single application at preplant, and LSNT — late spring soil N test based application) and manure (SM — fall injected swine manure) management effects on crop production and water quality. Data from 1978 to 2003 from a water quality experiment near Nashua (Nashua experiments), Iowa, USA, were used. The model was calibrated using data from one treatment plot and validated for the rest of the plots. Simulated management effects on annual N loading in tile flow were agreeable with measured effects in 85%, 99%, 88%, and 78% of the cases for tillage, crop rotation (CS vs. CC), N application timing (SA vs. LSNT), and swine manure applications (SM vs. SA), respectively. On average, the LSNT plots were simulated to have 359 kg ha^− 1 higher corn yield compared to SA, when the observed increase was 812 kg ha^− 1. Grain yield simulations were not sensitive to differences between RT and NT, between SM and SA treatments, and between CS and CC. We conclude that considering the uncertainties of basic input data, processes in the field, and lack of site specific weather data, the results obtained with this RZWQM-DSSAT hybrid model were not much better than the results obtained earlier with the generic crop growth module.     

4种荚蒾属植物种子内源抑制物存在特征初探

通过荚蒾种子浸提液对小白菜种子萌发的抑制作用,分析探讨荚蒾种子内源抑制物主要存在部位及其可溶性化学特征,为荚蒾属植物种子破除休眠提供科学依据。实验结果表明:4种荚蒾种子水和甲醇浸提液对小白菜种子萌发和胚根生长都有抑制作用,种皮水溶性抑制物活性:蒙古荚蒾朝鲜荚蒾暖木条荚蒾鸡树条荚蒾,胚乳水溶性抑制物活性:蒙古荚蒾鸡树条荚蒾暖木条荚蒾朝鲜荚蒾;种皮脂溶性抑制物活性:暖木条荚蒾蒙古荚蒾朝鲜荚蒾鸡树条荚蒾,胚乳脂溶性抑制物活性:鸡树条荚蒾朝鲜荚蒾蒙古荚蒾暖木条荚蒾。鸡树条荚蒾、朝鲜荚蒾、暖木条荚蒾内源抑制物主要是脂溶性物质,前两者较集中分布于胚乳,后者多存在于种皮;蒙古荚蒾以胚乳中水溶性抑制物为主。     

青海河湟地区水资源综合开发与区域经济发展研究

本文分析了河湟地区水资源特征、开发利用现状及存在的问题,在此基础上,论述了河湟地区水资源开发利用与区域经济发展模式。研究表明:加快开发黄河水能资源,建立以水能资源开采业为主导的产业群发展;浅山地区因地制宜推广雨水集流利用工程,走出“水窑+科技+节水产业+生态”的发展模式;“引大济湟”工程有助于提高水资源可利用量,推进湟水流域全面发展。     

绿色屋顶的雨水管理效能研究

文中讨论了绿色屋顶的雨水管理基本构成,分析了影响屋面雨水管理效能的各种因素,并从效能优化的角度提出了相应的设计策略。       

Impact of excreted nitrogen by grazing cattle on nitrate leaching

Abstract. At De Marke experimental farm, data on water and nitrogen flows in the unsaturated zone were gathered on two grazed pastures on sandy soils during the years 1991 to 1994. These provided a basis for calibration and validation of simulation models. The different levels of nitrate-N concentrations of the two plots could largely be explained by differences in crop uptake and simulated denitrification as influenced by different groundwater levels. The irregular distribution of excreta was taken into account by a simulation study quantifying the variability of nitrate-N concentrations under a grazed field. The resulting distribution of simulated nitrate-N concentrations explained the average and peak values of the measured concentrations. Temporal variability of weather was used to assess the nitrate leaching risk under urine patches deposited in either July or September. At site A the probability of exceeding the EC-directive by drinking water (11.3 mg/1 nitrate-N) under a urination deposited in either July or September was respectively 10 and 25%. The average field concentration at this site will hardly ever be a high risk for the environment under the current farm management. At site B the EC-directive will be exceeded under any urine patch in almost 100% of the years, affecting the field average concentration. In field B careful grazing management would result in less nitrate leaching, but the environmental goals would not be reached.     

Parameterization of the MACRO model to represent leaching of colloidally attached inorganic phosphorus following slurry spreading

Abstract. The dual porosity soil water and contaminant transport model MACRO was tested for its suitability to represent water flows and leaching of phosphorus (P) through field drains following spreading of slurry. These flows are characterized by very high loadings of P, including a high proportion in colloidally attached form, for about one week following winter spreading of slurry, followed by quite a rapid decline to the low background level. Use was made of the option in MACRO for representing colloid facilitated contaminant transport. The model simulates transport through macropores and soil matrix pores (micropores) of contaminant carrying colloids, as well as trapping of colloids by straining and filtration using an adaptation of standard filtration equations. Calibration involved selecting soil hydraulic parameters, colloid filtration coefficients and P sorption characteristics for two soils from measured and literature values. Both P in solution and P attached to colloids were represented in simulated outputs. Reasonable agreement was found between simulated and measured water and leached P flows. Work with the model suggests that macropore flow through the soil to field drains of colloidally transported P is an important component of water pollution associated with slurry spreading     

柳枝浸提液对小麦籽粒发芽的抑制作用研究

研究了柳树枝叶浸提液对小麦籽粒发芽的抑制效应，结果表明：抑制作用的大小随浸提时间和浸提液浓度的不同而异，煎煮时间对小麦种子发芽抑制强度依次为4h〉3h〉2h〉0．5h，浸提液不同浓度的抑制效果为280g／L〉200g／L〉120g／L〉40g／L。     

真空碳热还原酸浸含钛高炉渣制备TiC分析

含钛高炉渣中含有20%~30%的TiO 2,是一种附加值较高的二次资源,但在综合利用过程中存在氧化物还原难度大,硅钛难分离,二次污染严重等问题。基于热力学理论基础,采用真空碳热还原联合酸浸工艺处理含钛高炉渣制备TiC。结果表明：真空有助于钛氧化物彻底还原,可实现渣中硅钛彻底分离,减少酸耗量,降低二次污染。真空碳热还原联合酸浸工艺处理含钛高炉渣(TiO 2含量23%左右)制备TiC的最佳条件为：炉渣粒度200目,还原温度1 673 K,渣碳质量比100∶38。     

某硫矿重金属分级及土柱淋溶

Fractions of various heavy metals in a sulfidic minespoil were investigated.Column leachine experiment was also conducted to simulate “acid mine drainage“(AMD) from the minespoil.The results show that leaching of heavy metals from the minespoil was extremely significant during the initial water flushing.The amounts of heavy metals leached out dramatically reduced after leaching twice.It is worthwhile to note that in this study,Zn,Mn,Fe,As and Ni in the first leachate exceeded the total amount of each corresponding water-extractable(1:5,soil:water)metal contained in the minespoil sample.This appears to suggest that 1:5 water extraction did not allow accurate estimation of water-leachable concentrations of the above heavy metals.This work has implications for the management of sulfidic minespolis.Acid drainage of great environmental concerns is likely to occur only during heavy rainfall events after substantial soluble and readily exchangeable acid and metals are accumulated in the minespoils.The slow-reacting fractions other than water-soulble and readily exchangeable fractions may pose little environmental hazards.This is particularly true for Pb,As and Ni.     

厩肥对粉煤灰微量元素释放规律影响的研究

该文对粉煤灰在降雨淋洗条件下微量元素的释放规律进行了室内模拟试验。试验处理分别为粉煤灰、粉煤灰+石灰、粉煤灰+石灰+厩肥及其混合物的堆肥腐熟4种情况。实验结果显示淋出液中B、Sr、Ba和Li的最大浓度大于1 mg/L，而其它元素均小于此值。石灰的应用增大了淋出液中B和Ba的浓度而降低了Li、Mo和Cr的浓度；厩肥的应用及其堆肥腐熟处理增大了B、Mo、Zn、V以及Cu、Ni、Cd、As、Mn、Ti、Co、Sn和Se的浓度，而降低了Sr、Ba、Li和Cr的浓度。除V外，淋出液中所有微量元素的浓度随淋出液体积的增加而减小。Cr、Zn以及Cd、Cu和As可能是粉煤灰对环境产生潜在危害的主要元素。