The Inter-Annual Variability of Rainfall Onset and Its Implication on Crop Planting in Selected East Africa Countries

The inter-annual variability of rainfall onset and crop replanting in East Africa (EA) was assessed using daily estimated rainfall data from climate hazard group infrared precipitation (CHIRPS Ver2.0) and monthly Sea Surface Temperature (SST) indices [Indian Ocean Dipole (IOD) and El-Ni?o Southern Oscillation (ENSO) at NINO3.4 region] from the National Center for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR). The data covered a period of 40 years from1981 to 2020. The methods of cumulative of daily mean rainfall, percentage of onset date departure (PODD), Mann-Kendall (MK) trend test, student t-test, and correlation were applied in the analysis. The results showed that early onset with dry spell (WDS) consideration frequently occurs in Uganda between the first and second dekads of September, while late rainfall onset WDS occurs in the first and second dekads of December over central and Northern Kenya as well as in the Northeastern highlands, parts of the northern coast and unimodal regions in Tanzania. Rainfall onset with no dry spell (WnDS) portrayed an average of 10 days before the occurrence of true onset WDS, with maximum onset departure days (ODD) above 30 days across the Rift Valley area in Kenya and the Northeastern highlands in Tanzania. The high chance of minimum ODD is seen over entire Uganda and the area around Lake Victoria. However, few regions, such as Nakuru (Kenya) Gulu and Kibale (Uganda), and Gitega (Burundi), revealed a slight positive linear trend while others showed negative trend. Significant positive patterns for correlation between onset WDS and SST indices (IOD and NINO 3.4) were discovered in Northern and Northeastern Kenya, as well as areas along the Indian Ocean (over Tanzania’s Northern Coast). Inter-annual relationship between onset dates WDS and IOD (NINO3.4) indices exhibits a high correlation coefficient r = 0.23 (r = 0.48) in Uganda and r = 0.44 (r = 0.36) in Kenya. On the other hand, a negative correlation was revealed over Burundi and Tanzania (over a unimodal region). A high percentage of PODD was observed, ranging from 40% to 70% over the Rift Valley in Kenya and at the Northeastern highlands in Tanzania. However, a strong PODD above 70% was observed over Tanga and the Northern Pwani Region in Tanzania. These findings will help farmers to understand the appropriate time for crop planting, as well as help other socio-economic activities that strongly depend on rainfall.

Impact on Soil Organic C and Total Soil N from Cool- and Warm-Season Legumes Used in a Green Manure-Forage Cropping System

Annual forage legumes are important components of livestock production systems in East Texas and the southeastern US. Forage legumes contribute nitrogen (N) to cropping systems through biological N fixation, and their seasonal biomass production can be managed to complement forage grasses. Our research objectives were to evaluate both warm- and cool-season annual forage legumes as green manure for biomass, N content, ability to enhance soil organic carbon (SOC) and soil N, and impact on post season forage grass crops. Nine warm-season forage legumes (WSL) were spring planted and incorporated as green manure in the fall. Forage rye (Secale cereale L.) was planted following the incorporation of WSL treatments. Eight cool-season forage legumes (CSL) were fall planted in previously fallow plots and incorporated as green manure in late spring. Sorghum-sudangrass (Sorghum bicolor x Sorghum bicolor var. sudanense) was planted over all treatments in early summer after forage rye harvest and incorporation of CSL treatments. Sorghum-sudangrass was harvested in June, August and September, and treatments were evaluated for dry matter and N concentration. Soil cores were taken from each plot, split into depths of 0 to 15, 15 to 30 and 30 to 60 cm, and soil C and N were measured using combustion analysis. Nylon mesh bags containing plant samples were buried at 15 cm and used to evaluate decomposition rate of above ground legume biomass, including change in C and N concentrations. Mungbean (Vigna radiata L. [Wilczek]) had the highest shoot biomass yield (6.24 t DM ha-1) and contributed the most total N (167 kg∙ha-1) and total C (3043 kg∙ha-1) of the WSL tested. Decomposition rate of WSL biomass was rapid in the first 10 weeks and very slow afterward. Winter pea (Pisum sativum L. spp. sativum), arrow leaf clover (Trifolium vesiculosum Savi.), and crimson clover (Trifolium incarnatum L.) were the most productive CSL in this trial. Austrian winter pea produced 8.41 t DM ha-1 with a total N yield of 319 kg N ha-1 and total C production of 3835 kg C ha-1. The WSL treatments had only small effects on rye forage yield and N concentration, possibly due to mineralization of N from a large SOC pool already in place. The CSL treatments also had only minimal effects on sorghum-sudangrass forage production. Winter pea, arrow leaf and crimson clover were productive cool season legumes and could be useful as green manure crops. Mungbean and cowpea (Vigna unguiculata [L.] Walp.) were highly productive warm season legumes but may include more production risk in green manure systems due to soil moisture competition.

Crops Responses to Inter-Annual Climate Variability in Agroclimatic Zone of Sub-Saharan Africa

Climate variability has become a decisive factor for the crop yields in Sub-Saharan African countries. Inter-annual variability in rainfall has been the key climatic element that determines the success of agriculture in this region.From an analysis of recent rainfall conditions in West Africa,FAO(2001) concluded that a long-term change in rainfall has occurred in the semi-arid and sub-humid zones of West Africa.Thus,this study aims at assessing the vulnerability of crop yields to inter-annual variability in rainfall in sub-Saharan African countries taking Nigeria as a case study.A time series of the averaged value of the 12-Month Weighted Anomaly Standardized Precipita-

Impacts of climate change on the yields of leguminous crops in the Guinea Savanna agroecological zone of Ghana

The impacts of climate change on crop yields are receiving renewed interest,with focus on cereals and staple crops at the regional and national scales.Yet,the impacts of climate change on the yields of leguminous crops in the local context has not been explored.Thus,an in-depth understanding of climate change in the local context may support the design of locally relevant adaptation responses to current and future climate risks.This study examined the impacts of climate variables(annual rainfall,annual average temperature,rainfall indices(rainfall onset,rainfall cessation,and the length of rainy days),and the number of dry days)on the yields of leguminous crops(groundnuts,cowpeas,and soybeans)in the Guinea Savanna agroecological zone of Ghana during the period of 1989-2020.The data were analysed using Mann-Kendall’s trend,Sen’s slope test,correlation analysis,and Multiple Regression Analysis(MRA).The findings revealed that annual rainfall,annual average temperature,rainfall onset,rainfall cessation,and the length of rainy days,and the number of dry days all showed varied impacts on the yields of groundnuts,cowpeas,and soybeans.The trend analysis detected a marginal decrease in the amount of rainfall,rainfall onset,and the number of dry days from 1989 to 2020(P>0.050).Annual average temperature and the length of rainy days substantially varied(P<0.050)from 1989 to 2020,showing an increasing trend.The findings also showed a marked upward trend for the yields of groundnuts,cowpeas,and soybeans during 2005-2020.The climate variables analysed above increased the yields of groundnuts,cowpeas,and soybeans by 49.0%,55.0%,and 69.0%,respectively.The yields of groundnuts,cowpeas,and soybeans fluctuated with the variability of 30.0%,28.0%,and 27.0%from 2005 to 2020,respectively.The three leguminous crops under study demonstrated unpredictable yields due to the variations of annual rainfall,annual average temperature,rainfall onset,rainfall cessation,the length of rainy days,and the number of dry days,which stressed the need for agricultural diversification,changing planting dates,using improved seed variety,and irrigation to respond to climate change.The results of this study implied that climate change considerably impacts crop production in the Guinea Savanna agroecological zone of Ghana,emphasizing the urgency of locally based and farmer-induced adaptation measures for food security and resilient agricultural systems.

中国耕地种植制度遥感探测及其时空特征

[目的]耕地种植制度是农业生产方式的具体体现,其形成受自然资源要素与人类土地利用行为综合影响,反映了“人类-自然”的耦合关系。本研究旨在科学掌握全国耕地种植制度格局,为优化农业生产布局、提高农业生产能力、推动农业可持续性发展提供依据。[方法]结合遥感监测与空间决策树模型等手段,构建适合我国农情的跨年度种植制度探测方法体系,并开展空间格局分析。首先,通过辨析种植强度、复种指数等概念,从长期性、周期性、稳定性等方面,定义种植制度的内涵;其次,构建连续度、频度指标,并利用基于时序遥感的2001—2018年中国复种指数监测结果,结合时间滑动窗口方法,在像元尺度分别计算两个指标的具体值;最后,评估耕地的种植强度与种植制度特征的显著性,利用决策树方法确定种植制度类型,从区域差异、动态规律等方面分析不同区域种植制度的时空异质特征。[结果](1)面积上看,一年一熟所占面积最大,占53.52%,超过耕地总面积的一半;其次是一年两熟,占23.28%,季节性休耕(如两年三熟)与年度休耕分别占12.80%和6.94%。(2)空间上看,一年一熟、一年两熟、季节性休耕与年度休耕的集中分布区分别为东北地区、华北地区、长江以南地区与“镰刀弯”地区。(3)时间上看,动态稳定的种植制度从时间维度上揭示了静态复种指数背后的异质性,例如,2018年复种指数为1的区域,其中75.18%属于一年一熟、6.60%属于一年两熟、8.92%属于季节性休耕、8.02%属于年度休耕。[结论]本研究提出了一种结合时序遥感监测与空间决策树模型的跨年度分类体系,揭示了中国耕地种植制度分区聚集、种植强度南高北低的空间格局,直观展现了松嫩平原、“镰刀弯”等空间聚集区;分析了耕地复种与种植制度的时空差异特征,主要表现在种植制度与年度复种指数的空间不一致性,以及种植制度特有的周期性。研究结果可为合理提高耕地复种强度、推动实施“藏粮于地”战略提供案例支撑。

氮肥减量后移改善植株光合特性提高麦-玉周年产量及经济效益

【目的】针对黄淮海平原传统施氮技术下,小麦-玉米两熟体系作物生育后期土壤氮肥供应不足导致籽粒减产等问题,探讨氮肥减量后移对植株光合特性、干物质积累及周年籽粒产量和经济效益的影响,为进一步优化施氮制度提供理论依据。【方法】2020—2023年,于山东济阳典型麦-玉两熟种植区,设置周年施氮400 kg·hm^(-2)传统农户处理(CK,小麦季200 kg·hm^(-2):65%基肥+35%返青肥,玉米季200 kg·hm^(-2):100%基肥)、周年减氮10%(SN,小麦季180 kg·hm^(-2):50%基肥+50%返青肥,玉米季180 kg·hm^(-2):100%基肥)、周年减氮20%(NH,小麦季180 kg·hm^(-2):22.2%基肥+33.3%返青肥+44.5%抽穗肥,玉米季140 kg·hm^(-2):28.6%基肥+71.4%大喇叭口肥)和周年减氮30%(NL,小麦季140 kg·hm^(-2):43%返青肥+57%抽穗肥,玉米季140 kg·hm^(-2):100%大喇叭口肥)4种施氮制度,研究不同施氮制度下麦-玉两熟体系的光合特性、籽粒产量和经济效益。【结果】氮肥后移优化了氮肥减量条件下作物光合特性,其中,叶面积指数3年均值,小麦拔节和开花期NL较CK、SN和NH处理分别显著提高19.0%—40.1%和21.6%—36.7%,夏玉米吐丝期NL较CK和SN处理显著提高6.8%—7.3%;叶片SPAD值3年均值,冬小麦拔节和开花期NL较CK、SN处理分别显著提高7.7%—10.0%和7.4%—12.9%,灌浆中期NL较CK、SN和NH处理显著提高5.2%—16.2%;夏玉米大喇叭口期NL和NH较CK、SN处理3年均值分别显著提高9.0%—9.4%和6.7%—7.1%,吐丝和灌浆中期NL较CK、SN和NH分别显著提高5.1%—9.4%和4.1%—9.2%;净光合速率3年均值,小麦拔节、开花和灌浆中期NL较CK、SN处理分别提高8.9%—13.3%、14.0%—18.1%和20.1%—24.4%;夏玉米大喇叭口、吐丝和灌浆中期NL较CK、SN处理分别提高4.2%—5.7%、8.7%—13.4%和7.7%—12.8%。NL处理通过增加氮肥后移量,改善了各生育阶段地上部干物质积累强度,稳定或提高了各生育时期地上部干物质积累量,冬小麦拔节、开花和成熟期地上部干物质积累量的3年均值较CK分别显著提高26.7%、27.4%和18.1%,夏玉米吐丝期显著提高14.4%。氮肥后移通过改善氮肥减量条件下光合特性,促进了各生育时期地上部干物质积累,最终实现冬小麦、夏玉米及周年籽粒产量的3年均值,NL较CK处理分别显著提高20.5%、18.1%和19.1%,经济效益分别显著提高32.4%、23.8%和27.9%。【结论】黄淮海平原麦-玉两熟体系,周年减氮30%制度下通过增加氮肥后移量,改善了作物光合特性(叶面积指数、叶片SPAD值和净光合速率),优化了各生育阶段地上部干物质积累强度和干物质积累量,从而促进冬小麦、夏玉米及周年总产和经济效益的提高。

不同降水年型与不同茬口对小麦植株氮素吸收转运与利用的影响

为明确不同降水年型与小麦植株氮素吸收转运的关系,探索不同茬口的高效生产技术路径,本试验连续2年在河南驻马店农业科学院试验示范基地,研究不同降水年型和不同茬口对小麦植株氮素吸收利用、转运特性以及氮效率的影响。结果表明,丰水年较歉水年有利于大豆茬小麦植株氮素的吸收,提高小麦植株氮素的积累,促进花后积累的氮素向籽粒中运转;大豆茬和花生茬较玉米茬均可提高小麦植株含氮率,有利于小麦植株氮素积累,促进叶片和茎秆+茎鞘中的氮素向籽粒转移,提高小麦植株花前氮运转量和氮素转移率,最终增加小麦籽粒的氮效率和籽粒产量;丰水年较歉水年可明显提高不同茬口小麦植株的氮素吸收效率及氮素生产效率。不同降水年型下,大豆茬和花生茬均可促进小麦植株氮素吸收,有利于花后氮素积累向籽粒的运转,从而提高籽粒产量,最终提高小麦植株氮素利用效率,在歉水年条件下以大豆茬效果较好,丰水年条件下以花生茬效果较好。

“春白菜—夏黄瓜—秋生菜”一年三作高效栽培技术

从茬口安排、品种选择、田间管理、病虫害防治等方面,详细介绍了大棚蔬菜种植中“春白菜—夏黄瓜—秋生菜”一年三作高效栽培技术,以供蔬菜种植户参考。

Impact of Annual Ryegrass on Nitrate-N Losses during One Growing Season of Maize in the Midwestern United States <br/>—An On-Farm Case Study

Winter cover crops have been shown to reduce nitrate-N (NO3-N) losses in runoff water and are recommended by the Illinois Nutrient Loss Reduction Strategy (NLRS) for reducing nutrient losses from agricultural fields. With an estimated 80 percent of the NO3-N load in Illinois coming from agriculture, the NLRS stresses the importance of farmers’ voluntary implementation of best management strategies in order to reach these goals. This study compares the difference in NO3-N losses from tile drainage water from an annual ryegrass (AR, Lolium multiflorum) winter cover-cropped treatment to a conventional tillage (CT) control (fall chisel and spring field cultivation). Throughout the maize (Zea mays L.) growing season, tile drainage water was collected and analyzed for NO3-N concentrations. Despite the AR treatment having a 29% lower mean daily NO3-N concentration, there was no significant difference in total daily NO3-N flux between AR and CT for this study period of April-July 2015. The cumulative losses of NO3-N were calculated at 11.65 and 10.56 kg ha?1 NO3-N for the CT and AR treatment, respectively, or a 9.4% reduction in the AR treatment during the period of study. When the season was divided based on growing season periods, the NO3-N flux values were less for the cover crop while the AR was actively growing, greater for the cover crop for the period following annual ryegrass termination through maximum crop canopy, and lower for the cover crop in the late stages of vegetative growth through relative maturity.

Uptake of U-and Th-series radionuclides by cereal crops in Upper Egypt

The main aim of this study is to determine the activity concentrations of uranium series and thorium series radionuclide in crops cultivated in Upper Egypt.Fifteen types of cereal crops were collected from local markets and analyzed by γ-ray spectrometry.The mean activity concentrations of the natural radionuclides 238U,226Ra and 232Th were 0.67,1.27 and 0.56 Bq·kg-1,respectively.The annual effective doses from these radionuclides were estimated for different age groups.

极端气温事件对贵州茶叶种植面积及产量的影响分析

选取贵州省19个气象站点1980—2019年间逐日最高、最低气温数据,运用Sen斜率、Mann-Kendall(M-K)法和Pearson相关分析等方法,对贵州省1980—2019年极端气温事件变化特征及其对贵州茶叶的种植面积及产量的影响进行分析。结果表明:1980—2019年间贵州省极端气温指数中的夜指数的增加幅度大于昼指数的增加幅度;近40年来,贵州省茶叶种植面积和产量在2000年前变化趋势不明显,而在2000年之后呈现出快速增加的趋势;贵州省茶叶种植面积与产量主要是受冷昼日数(TX10p)、冷夜日数(TN10p)、气温日较差(DTR)、热夜日数(TR)、夏日日数(SU)、暖夜日数(TN90p)、暖昼日数(TX90p)和日最低气温最大值(TNx)这8个极端气温指数的影响,其他几个指数对茶叶种植面积与产量影响较小。

目标树经营对油松人工林生长的影响

为了解目标树经营对油松生长的影响,以冀北山地典型油松人工林为研究对象,对采取目标树经营及未经营的油松人工林的径生长进行了比较分析。研究结果表明,目标树经营实施4年后,油松人工林的径级结构明显向右偏移,对照样地的径级结构则未发生明显变化;经营样地平均木胸径和胸高断面积年生长量分别为对照样地的1.55倍和1.81倍(P<0.05);目标树胸径及胸高断面积生长量分别为平均木的1.24~1.58倍和1.55~2.01倍(P<0.05);目标树经营明显促进了大径级林木的蓄积生长量,经营样地大径级(DBH>20 cm)林木生长率为对照样地的1.33倍;油松对目标树经营措施响应迅速,采取经营措施后,经营林分与对照林分的胸径生长过程出现明显分化。由此得出结论,目标树经营措施明显促进了油松人工林目标树的生长,达到了培育优质大径材的目标。

机遇与挑战:多年生作物研究进展

随着全球气候的急剧变化,人们期望改变传统的农业生产模式,建立可持续性发展的低碳绿色农业生产体系。中国的粮食作物种植收益低,年轻人不愿意从事农业生产,耕地撂荒问题愈发严重。传统农作物大都是一年生作物,生产中需要使用大量的化肥、农药,由此带来了严重的环境生态问题;此外,经过长期人为选择的一年生作物,普遍对环境变化的适应能力较弱,越来越难以适应复杂的气候变化。而多年生粮食作物的生命周期较长,可以连续多年生长,比一年生作物的自然资源利用率更高、劳动力投入更少、环境适应力更强。而且多年生作物一般根系发达,除了可以减少水土流失,还能减少碳元素从土壤向大气中的转移,有利于截留更多的碳、发展低碳绿色农业。因此,发展多年生作物是目前实现农业可持续发展的重要途经之一。目前,多年生作物的培育还存在着一定的困难,不过新技术的出现和发展大大加速了多年生作物驯化过程,在改良多年生作物农艺性状的同时,保持与多年生有关的生长特性。

节水灌溉对冬小麦/夏玉米周年两熟作物光合和细胞保护参数及产量性状的影响

改善河北平原区节水栽培冬小麦/夏玉米周年两熟作物生产能力对于促进该生态区水资源可持续利用和保障我国粮食安全具有重要实践意义。本研究在前期工作基础上,对节水灌溉处理下小麦和玉米群体物质生产、光合特性、细胞保护系统特征和产量进行了研究。与生产通常采用的灌溉对照相比,小麦节水处理T1(灌溉底墒水和拔节水,节水44.4%)和玉米节水处理T2(灌溉蒙头水和吐丝水,节水42.1%)生育后期群体干物质量、光合参数和细胞保护酶活性均表现不同程度下降。此外,成熟期T1小麦穗数、穗粒数、千粒重、产量以及T2玉米穗粒数、千粒重和产量较对照(CK)也呈不同程度降低(降幅1.69%~9.21%)。与CK相比,T3处理下,小麦群体干物质量、光合参数、细胞保护系统参数和产量性状表现与T1相似,玉米上述性状表现与T2相似。但与CK相比,T1和T2处理生育期间耗水量减少(小麦减幅20.54%,玉米减幅12.73%),植株水分利用效率显著提高(增幅5.37%~8.40%)。表明节水灌溉处理下,小麦和玉米通过维持生育后期良好光合和细胞保护系统功能,改善植株群个体发育和干物质生产能力,实现周年小麦玉米两熟生产下较高产量水平。

我国葡萄一年两收栽培的区划研究进展

葡萄一年两收栽培技术是指一年生产两造（两茬、两季）葡萄的栽培模式,通过促进葡萄二次花芽分化,利用绿枝夏芽、冬芽当年开花,或打破老熟枝条冬芽休眠,形成两季葡萄产量。文章通过分析我国葡萄一年两收不同产区的气候条件与栽培模式,并与葡萄生长所需的气候要求进行对比,对不同区域适用的栽培模式及品种类型进行划分,得知年均气温是决定能否发展葡萄一年两收栽培的关键气象因子。年均气温在20.0℃以上的南方地区可在露地进行早、中熟品种的两代不同堂一年两收栽培,是葡萄特殊优势栽培区,年均气温17.5-20.0℃的地区可进行早熟品种的两代不同堂一年两收栽培和早、中熟品种的两代同堂一年两收栽培,年均气温16.0-17.5℃的地区可进行早熟品种的两代同堂一年两收栽培;北方年均气温在12.0℃左右及以上的地区,采取适当的栽培措施也可在露地条件下实现早熟品种的两代同堂一年两收栽培,在日光温室等设施栽培条件下,即使年均气温仅在5.0℃左右也可进行一年两收栽培生产。

耕作方式对冬小麦–夏玉米光合特性及周年产量形成的影响

【目的】作物的光合特性及干物质积累与转运是影响产量的重要因素。研究不同耕作方式对冬小麦–夏玉米光合特性、干物质积累转运及周年产量的影响,以期为冬小麦–夏玉米两熟地区选择适宜的耕作方式提供理论和实践依据。【方法】以黄淮海地区2003~2014年连续12年定位试验为平台,在秸秆还田前提下,试验设4种耕作方式:传统翻耕(PC)为对照、免耕(PZ)、深松(PS)和旋耕(PR)。对2014~2015季冬小麦和2015季夏玉米各项光合参数、干物质积累和产量进行了测定。【结果】长期不同耕作方式对冬小麦–夏玉米光合特性和周年产量影响显著,免耕、深松和旋耕处理的光合特性和周年产量均优于对照传统翻耕,依次为PS>PZ>PR>PC。PZ、PS和PR耕作方式显著提高了生育后期冬小麦和夏玉米功能叶的叶绿素含量、光合速率、气孔导度和蒸腾速率,其中冬小麦灌浆后期叶绿素含量分别提高了97.0%、121.1%和71.4%,光合速率分别提高了57.6%、71.6%和51.2%;夏玉米灌浆期叶绿素含量分别提高23.6%、28.1%和10.4%,光合速率分别提高18.6%、26.5%和19.2%,延缓了叶片衰老,使光合作用始终维持在较高水平。PZ、PS和PR处理冬小麦花后同化物对籽粒的贡献率分别达65.3%、67.8%和65.0%,夏玉米为66.3%、70.6%和63.4%,而对照处理(PC)冬小麦和夏玉米的贡献率仅为59.3%和60.9%。PZ和PS处理冬小麦和夏玉米的穗粒数和千粒重显著高于PC处理,穗数显著低于PC和PR。PZ、PS和PR可显著提高周年产量,分别提高15.4%、18.2%和11.0%。【结论】在黄淮海地区,采用长期秸秆还田下免耕、深松和旋耕均可提高冬小麦和夏玉米叶绿素含量和光合速率,提高胞间CO_2利用能力,降低非气孔限制,增强花后干物质积累能力,增加花后同化物对籽粒的贡献率,协调产量构成因素的关系,提高单季和周年产量,其中深松效果最佳,免耕次之。

耕作方式对华北一年两熟区土壤及作物特性的影响

为了研究不同耕作方式在华北一年两熟区的适应性,设置深松、旋耕、传统翻耕、免耕4种不同耕作方式,分析耕作方式对土壤水稳团聚体、容重、含水率、土壤温度和植株生长特性的影响。结果表明:免耕、深松可分别提高0~10 cm、10~30 cm土层内粒径大于0.25 mm水稳团聚体的含量;随土层深度的增加,土壤容重增大,其中旋耕、深松分别降低0~10 cm、10~30 cm土层的容重,在0~20 cm土层免耕的容重最大,20 cm以下,旋耕、翻耕、免耕间容重的差异不明显;深松有较好的蓄水保墒能力,其中10~30 cm土层的效果最好,0~30 cm土层的含水率分别比翻耕、旋耕、免耕高2.5%、1.6%、0.4%;翻耕的土壤温度受气温影响的变化幅度最大,免耕的变化幅度和日平均土壤温度最小;深松可促进玉米前期的生长,免耕促进后期生长,且深松能提高冬小麦的产量。

高寒牧区一年生牧草种间竞争的动态研究

在河北坝上高寒地区，用替代试验(相同密度400粒／m2下5种播种比例，6次刈割)研究了燕麦(冬牧70黑麦)＋箭舌豌豆混播草地种间竞争的动态变化，结果表明，巴燕6号燕麦(冬牧70黑麦)在混播群落中其竞争力一直超过箭舌豌豆，箭舌豌豆处于竞争劣势地位。

秸秆还田对农田周年地表径流氮、磷、钾流失的影响

2009—2010年在大田试验条件下,小麦季和水稻季分别以扬麦16和运2645为供试材料,两季均设置常规处理(A)、秸秆还田(B)、秸秆还田减肥(C)、肥料运筹(D)和少免耕(E)5个处理组合。研究不同处理对稻麦两熟制农田周年地表径流氮、磷、钾流失的影响。结果表明:(1)稻麦两季农田共发生地表径流20次,总地表径流水量为6.4×106kg·hm-2;(2)秸秆还田能够显著降低稻麦两熟制农田周年地表径流氮、磷、钾流失量,不同处理周年地表径流总氮和钾的流失量由高到低均依次为少免耕、常规处理、肥料运筹、秸秆还田和秸秆还田减肥,不同处理周年地表径流总磷流失量由高到低依次为少免耕、肥料运筹、常规处理、秸秆还田和秸秆还田减肥,秸秆还田使稻麦两熟制农田地表径流氮、磷、钾流失量分别比常规处理下降7.7%、8.0%、6.8%;(3)水稻季农田地表径流总氮、总磷、钾流失量分别占稻麦两熟制周年总氮、总磷、钾流失量的61.5%、44.0%、73.3%;(4)秸秆还田使稻麦两熟制农田周年地表径流氮、磷、钾流失率显著降低;(5)秸秆还田使水稻成熟期土壤速效养分质量分数显著提高;(6)秸秆还田使稻麦两熟制农田周年作物产量比常规处理略有增加。

河南省参考作物蒸散量变化特征及其气候影响分析

基于河南省111个气象站1971-2010年逐日平均气温、最高气温、最低气温、相对湿度、风速和日照时数等气候要素资料,应用Penman-Monteith模型计算各站点逐日参考作物蒸散量(ET0),结合数理统计方法,分析近40a来河南省年ET0的时空变化特征,并对其主要影响因子进行探讨。结果表明,Penman-Monteith模型对河南省ET0的模拟能力较强,模拟值与同期小型蒸发皿蒸发量的相关系数r=0.84(P<0.01)。近40a,河南省年ET0平均值为796.1mm(±102.2mm,n=4169),在空间分布上,总体表现出北高南低的特征,并以24.7mm.10a-1(P<0.01)的线性倾向率减少,呈明显减少的站点主要分布在34°N以北地区。偏相关分析表明,全省各地(市)年ET0与各气象要素关系密切,除济源外,年ET0均表现出与风速呈负相关且相关系数最大。逐步回归分析显示,年ET0与平均气温、日照时数、风速和相对湿度的关系密切;风速、日照时数和平均气温对年ET0的贡献为正效应,而相对湿度为负效应。近40a,风速减小是导致河南省年ET0呈显著减小的主要原因;但从综合影响看,这是各气象因素综合作用的效果,且各因子的贡献存在区域差异。