Effects of tillage, weed control method and row spacing on soybean yield and certain soil properties

Soybean (Glycine max (L.) Merr.) is an important crop in the southeastern United States, and thus there is a need for additional information on the effects of tillage, weed control methods and row spacing on soybean yields, weed populations and soil properties. The objective of this study was to determine the effects of three weed control methods (none, cultivation, and herbicide) and three row spacings (45, 60 and 90 cm) on soybeans planted in a conventionally prepared seedbed or planted in wheat stubble (no-till (NT)) on a Decatur silty clay loam (Rhodic Paleudult) soil during the 1987 and 1988 growing seasons. Following NT planting, soybean plots produced a seed yield of 3102 kg ha⁻¹ with herbicide, 2911 kg ha⁻¹ with cultivation and 2216 kg ha⁻¹ with no weed control. On a conventionally prepared seedbed, herbicide and cultivation resulted in almost equal seed yields (3898 kg ha⁻¹ and 3954 kg ha⁻¹ respectively) which were significantly higher than those from the no weed control plots (3151 kg ha⁻¹). Soybeans in narrow (45 cm) rows (3997 kg ha⁻¹) consistently out-yielded those in the wider 60 cm rows (3130 kg ha⁻¹) and 90 cm rows (2490 kg ha⁻¹) in both growing seasons, results averaged across years showed that conventionally planted soybeans produced higher yields (3668 kg ha⁻¹) than NT planted soybeans (2743 kg ha⁻¹). The weed infestation was significantly less with herbicide or cultivation than with no weed control and also less in narrow rows (45 cm) than in wider rows (60 and 90 cm). Data on the soil properties (from a depth of 0–15 cm) showed that moisture content, organic matter content and total soil nitrogen were higher in NT plots than in conventional plots. Similarly, disease ratings and infestation of bacterial blight of soybean were significantly higher in NT than in conventional tillage systems.     

行距和行向对不同密度玉米群体田间小气候和产量的影响

"浚单20"是目前我国种植面积较大的紧凑性高产玉米品种。为充分发挥该品种在安徽种植区域的高产潜力, 开展了种植密度、行距和行向三者相配置的田间试验, 在60 000株·hm^-2和67 500株·hm^-2两种种植密度下, 研究了不同行距和行向对"浚单20"的田间小气候和玉米产量的影响。结果表明: 随着行距增大, 玉米群体内部的日均风速和日均光照强度逐渐增大, 累计积温和日均相对湿度则呈下降趋势。在同一种植密度和行距条件下, 东西行向种植比南北行向种植的玉米群体日均风速较大、日均光照强度较高、累计积温较低和日均相对湿度较小, 且产量高。同一种植行向, 不同种植密度和行距配置条件下, 玉米产量差异达显著水平(P<0.05)。其中种植密度为60 000株·hm^-2, 东西行向种植, 行距为50 cm时, 玉米群体结构较为合理, 所形成的田间小气候较有利于"浚单20"的生长发育, 籽粒产量达到10 582.5 kg·hm^-2。通过研究阐明了行距、行向和密度三者不同配置所形成的田间小气候与玉米产量形成的关系, 为提高"浚单20"在安徽省的种植水平提供指导。     

不同播量与行距对小麦产量与辐射截获利用的影响

在田间试验条件下,设置了3个播种量(6 kg·667m 2、9 kg·667m 2和12 kg·667m 2)和3个种植行距(20 cm、25 cm和30 cm)共9个处理。通过测定小麦群体生长动态、辐射截获量和籽粒产量,研究分析不同行距和播种量对小麦产量形成和辐射利用效率的影响。结果表明:群体总茎数和叶面积指数表现为随播种量增大而增加;在相同播种量下,尽管20 cm行距的小麦分蘖数最高,但其有效成穗数却最低;叶面积指数与群体总茎数变化动态一致,而叶日积却表现为随行距和播量加大而增加。在相同播种量下,籽粒产量和辐射利用效率均随着种植行距增加呈递增趋势变化,在3个播种量下表现趋势一致。行距由20 cm增加到25 cm和30 cm,籽粒产量平均增加81.62 g·m 2和162.53 g·m 2,截获辐射利用效率平均增加0.18%和0.35%。产量和截获辐射利用率在行距间的差异均达到极显著水平,而播种量之间没有表现出显著差异,播种量和行距之间也没有明显互作效应。由此说明:调整行距对产量的影响作用大于调整播种量对产量的影响作用。因此,在水肥条件较好的黄淮海平原区小麦生产中,把传统种植行距15~20 cm调整为25~30 cm,播种量在常规播种量的基础上适量增加,可以提高小麦单产与辐射资源利用潜力。     

行距配置方式对夏玉米氮素吸收利用及产量的影响

为确定黄淮南部夏玉米产区机械化生产适宜的行距配置方式,2012—2013年同时在河南省方城县和辉县两个试验点设置大田试验,以高、中、低3种株高类型的玉米杂交种‘先玉335’、‘郑单958’和‘512-4’为材料,设置2个种植密度(低:60 000株·hm~(-2);高:75 000株·hm~(-2))、5个行距配置方式(50 cm、60 cm、70 cm、80cm等行距和80 cm+40 cm宽窄行距),研究了不同株型玉米品种在不同密度和行距配置条件下对氮素吸收利用效率和产量的影响。结果显示,低密度种植条件下,高秆的‘XY335’和矮秆的‘512-4’均以60 cm等行距处理产量优势明显;中秆的‘ZD958’在辉县和方城分别以60 cm和70 cm等行距产量最高。在高密度种植条件下,高秆的‘XY335’和中秆的‘ZD958’均以60 cm等行距处理产量最高;而矮秆的‘512-4’则以50 cm等行距种植产量优势明显,但与60 cm等行距处理差异不显著。植株氮积累量随行距的扩大呈先升高后降低的趋势,以60 cm等行距的氮积累量较大,低密度时显著高于80 cm等行距和80 cm+40 cm宽窄行距处理,而高密度下与各行距处理差异不显著;不同品种植株氮积累量对行距反应不同,高秆品种在行距间差异不显著,中秆品种80 cm等行距最低且与其余行距处理差异显著,矮秆品种50 cm和60 cm等行距氮积累量最高且与其余行距差异显著。两个密度种植条件下,籽粒氮积累量和氮素收获指数均随行距的扩大先升高后降低,在60 cm等行距处理达到最大值,并且均显著高于其他行距处理;氮肥偏生产力随行距的扩大呈现先升高后降低的趋势,60 cm等行距处理较高,但在低密度下与其他行距处理差异不显著,高密度时与80 cm等行距处理差异显著。与其他行距处理相比,60 cm等行距处理具有相对较高的氮素吸收利用效率和产量,能够较好地协调玉米土壤与植株的氮素吸收利用关系,兼顾不同株高类型玉米品种在一定密度范围内获得高产,可作为目前黄淮南部地区夏玉米统一的行距配置方式进行推广。     

河西灌区不同耕作与秸秆还田方式对春小麦出苗及产量的影响

出苗率及出苗整齐度在很大程度上决定了作物生长状况和产量丰欠,针对不同耕作措施结合秸秆还田对绿洲灌区小麦出苗及群体动态影响研究薄弱问题,研究不同秸秆还田与耕作方式对小麦出苗与产量的影响,以及二者的相关关系,对于优化耕作措施具有重要指导意义。2014—2015年,在甘肃河西绿洲灌区,通过田间定位试验,研究了不同秸秆还田和耕作措施[少耕25~30 cm高茬收割秸秆立茬还田(NTSS)、少耕25~30 cm高茬收割秸秆覆盖还田(NTS)、翻耕25~30 cm高茬收割秸秆还田(TS)和不留茬翻耕(CT)]对小麦出苗状况及产量、产量构成因素的影响,以期为优化试区小麦栽培技术提供依据。结果显示,与CT相比,NTSS、NTS降低了小麦出苗率以及出苗整齐度,TS则提高了小麦出苗率以及出苗整齐度。NTSS、NTS较CT的分蘖数分别高7.4%~10.5%、14.6%~19.1%,分蘖成穗率分别高13.5%~20.1%、33.0%~34.7%,有效穗数分别高7.5%~9.3%、10.3%~11.2%,穗粒数分别高15.7%~16.1%、18.5%~22.6%,千粒重分别高7.2%~8.9%、13.9%~14.2%,但TS与CT在以上指标间没有显著差异。NTSS、NTS与CT相比较,分别增产16.6%~17.4%、18.6%~21.4%,以NTS增产幅度较大,比TS高10.3%~11.0%。穗数和穗粒数的增加是少耕秸秆还田获得高产的主要原因,出苗率及整齐度对产量影响不显著。同时NTSS和NTS均获得较高的收获指数,提高比例分别为9.4%~10.7%与10.5%~11.1%,说明少耕秸秆还田提高籽粒产量的另一原因是提高了光合产物向籽粒中的转化。本研究表明,少耕秸秆还田是适用于试区小麦高产的理想耕作措施。     

不同机械化耕播模式对冬小麦幼苗质量和产量的影响

该研究选用不同小麦耕播复式作业机械,并以传统耕播机械及人工撒播种植为对照,进行不同机械化耕播模式对小麦幼苗生长和产量的影响研究,以期为小麦高产高效机械化栽培提供理论与实践依据。研究结果表明,LCB-10型小麦精确施肥旋耕播种机复合作业模式（模式2）与双轴分层切削施肥播种镇压开沟复式作业模式（模式1）的作业效率、植被覆盖率和出苗率高,越冬初期的幼苗叶面积与干物质积累量均较大,越冬苗体健壮度高,群体穗数与总粒数多,产量高,经济效益好,适宜大面积推广。其中模式2与模式1的作业效率比其他模式分别高0%～260%、100%～620%,2 a出苗率平均高6.77%～20.60%、6.13%～19.87%,2 a产量平均分别达9 894.38和9 689.64 kg/hm2,分别比其他模式高23.84%～42.90%、21.28%～39.94%,2 a经济效益平均分别比其他模式高51.54%～112.68%、46.94%～106.23%;模式2的播种深度较深,出苗均匀度不高,而模式1的露籽率相对较高;2BFG-10（6）230旋耕智能施肥播种机复合作业模式（模式4）的植被覆盖率高于模式3（LCB-10型小麦精确施肥旋耕播种机少免耕机条播模式）与模式6（传统浅旋耕整与人工撒播模式）,出苗率与出苗均匀度高于模式3、模式5（传统机械施肥旋耕撒播模式）与模式6,露籽率少于模式5与模式6,群体干物质积累量较高,成熟期群体穗数、总粒数、产量与经济效益也均显著高于模式3、模式5与模式6,其中2 a产量平均高7.01%～15.39%,经济效益高14.23%～40.35%,也较适宜大面积推广应用。模式6由于大量使用人工,人工成本高于机械费用,虽播深适宜,但作业效率低,露籽率高,出苗均匀度差,幼苗单株分蘖数少,成熟期穗数少,穗型小,产量与经济效益最低,不适合小麦规模化丰产高效生产。     

Influence of nitrogen rates and row spacing on corn yield,protein content,and other plant parameters

New maize hybrids has been intensively used as the first and second crop at the Cukurova region of Turkey in recent years. Therefore, nutritional problems of corn needs to be solved for the optimum yield, and protection from the potential insect and disease damages. Influence of nitrogen (N) and row spacing (RS) on corn yield, grain protein content, and selected plant parameters have been studied under field conditions in 1994 and 1995. Nitrogen was applied in the rates of 200, 250, 300, and 350 kg N ha^‐1 to main plots where row spacings were 10, 15, 20, and 25 cm in each subplots. Phosphorus (P) and potassium (K) were applied to each plot as basal rates. The experiment was arranged in a split‐plot design in three replications. During course of the experiment and after harvest, selected plant parameters, leaf nutrient contents, root length, grain yield, and crude protein content were measured, and the data were statistically analyzed for determination of treatment effects. The selected plant parameters either influenced by N, RS, or both in 1994 and 1995. The leaf N content was affected by N and RS in 1995, and a RS effect was only observed in 1994. Grain yield was influenced by RS and N and RS in the first and second years, respectively. Grain yield ranged between 7.3 to 12.8 Mg ha"¹ for both years. Treat ment effects on crude protein content was significant in 1994 but no response was obtained in 1995.     

改变玉米行距种植对豌豆/玉米间作体系产量的影响

间作体系中改变作物的种植行距可改变体系作物的种间互作效应,影响作物产量。本研究通过设置豌豆/玉米间作种植体系中玉米的5种种植行距(0 cm、20 cm、40 cm、60 cm和80 cm),以期揭示间作体系中作物种植行距变化对体系作物产量的影响。结果表明:豌豆/玉米间作体系产量优势明显,各处理的土地当量比均大于1。玉米种植行距在0~80 cm区间改变时对体系产量的影响总体表现为随玉米行距增大,产量先增后降,且玉米种植行距与体系混合产量和间作玉米产量均呈现二次曲线相关关系,产量峰值出现在玉米种植行距为40 cm时,间作玉米产量达10 118 kg.hm 2。玉米行距变化对豌豆产量的影响不明显,间作体系产量主要受间作玉米产量影响。改变玉米行距种植明显改变了玉米的产量性状,主要表现在穗粒数上,行距为60 cm时,穗粒数最大,达549粒。种间相对竞争力总体表现为随玉米行距的增大玉米相对于豌豆在产量形成方面的竞争力逐渐增强;在玉米行距0~60 cm之间,豌豆相对于玉米的种间相对竞争力均<0,表明竞争力玉米强于豌豆,而当玉米行距为80 cm时,种间竞争力为0.14,表明此时豌豆竞争力强于玉米。因此,通过合理调整玉米种植行距从而提高间作玉米产量有利于提高豌豆/玉米间作体系的整体产量。     

Impact of tillage and nitrogen on cotton yield and quality in a wheat-cotton system,Pakistan

Growing cotton (Gossypium hirsutum L.) after wheat (Triticum aestivum L.) is an important cropping system in Pakistan. However, numerous tillage practices commonly applied for cotton production are not productive. Conservation tillage may optimize cotton yield and quality if nitrogen (N) is not a limiting factor. Field experiments were conducted on silty clay soil (Hyperthermic, and Typic Torrifluvents) of Dera Ismail Khan, Pakistan to study the impact of tillage techniques (zero (ZT), reduced (RT), and conventional tillage (CT)) and nitrogen, namely 0, 50, 100, 150, and 200 kg ha^–1 on cotton yield and quality. Mean values for N revealed that bolls plant^–1, boll weight, seed cotton yield, ginning out turn (GOT), fiber length, strength, and micronaire were highest at 150–200 kg N ha^–1. Averaged over years, tillage × nitrogen revealed that RT had higher bolls plant^–1, boll weight, GOT, fiber length, and strength at 150–200 kg N ha^–1 compared to other tillage system. The micronaire revealed that RT had no adverse effect on fiber fineness compared to ZT/CT. RT had accumulated higher soil organic matter and total soil N compared to CT. RT with 150–200 kg N ha^–1 may be a sustainable and environmentally safe strategy to enhance cotton yield and quality.     

施氮量与行距对冬小麦品质性状的调控效应

在当今小麦产量不断提高的同时,籽粒品质逐渐受到人们的重视,不同的栽培措施会对小麦籽粒品质产生一定影响。为探明施氮量与行距互作对强、中筋小麦品质的调控效应及小麦类型间差异,于2013—2014年在中国农业科学院作物科学研究所中圃场试验田,以强筋小麦‘济麦20’和中筋小麦‘中麦8号’为试验材料,采用裂区试验设计,以施氮量(150 kg·hm-2、210 kg·hm-2、270 kg·hm-2)为主区,行距(12 cm、20 cm)为裂区,供试品种为小裂区,研究田间高产栽培条件下不同施氮量和行距配置对不同类型冬小麦品质的影响。结果表明,‘济麦20’和‘中麦8号’花后蛋白质积累量、成熟期籽粒蛋白质及其组分含量均随施氮量和行距增加而显著提高,且在低氮条件下施氮效果较为显著。在270 kg·hm-2施氮量水平下,增大行距对2个小麦品种灌浆后期籽粒蛋白质积累量的影响存在显著差异。在20 cm行距条件下,210 kg·hm-2施氮量有利于强筋小麦‘济麦20’硬度、出粉率、湿面筋含量、沉降值及粉质参数等品质指标的改善,而270 kg·hm-2施氮量能够有效提高中筋小麦‘中麦8号’磨粉品质和粉质参数;2个筋型小麦面包体积和面包评分均随着施氮量的增加而升高,而2个小麦品种容重随施氮量的增加而显著下降。当施氮量在150 kg·hm-2以上时,增大行距,‘济麦20’和‘中麦8号’加工品质均能够显著提升,即在20 cm行距水平下2个筋型小麦加工品质较好。适当的施氮量和合理的行距配置能够提高小麦籽粒品质,本试验条件下,‘济麦20’和‘中麦8号’籽粒品质在行距20 cm、施氮量分别为210 kg·hm-2和270 kg·hm-2时达到最优。说明适当增加施氮量和增大行距均有利于强、中筋冬小麦品质的改善。     

Effects of naturally and microbially decomposed cotton stalks on cotton seedling growth

Cotton stalk directly returning to cotton field has impeded the cotton growth to a large extent in Xinjiang province, China. The allelopathic effects of products from naturally and microbially decomposed cotton stalks on the cotton seedling growth were studied. The results showed that when the seedlings were treated with the 30-day microbially decomposed cotton stalks, they displayed better growth and physiological characteristics than those treated with the products of 30-day naturally decomposed cotton stalks. When treated with the microbially decomposed cotton stalks at a low concentration of 5 g kg^?1, the seedling dry weight and plant height even increased significantly compared to the untreated control (P < 0.05). The gas chromatography–mass spectrometry analysis showed that two compounds, dibutyl phthalate (DBP) and diisobutyl phthalate (DIBP), were detected with higher concentrations in the naturally decomposed cotton stalk extracts, which strongly inhibited the cotton seedling growth in bioassay, suggesting the two compounds might be the responsible allelochemicals inducing autotoxicity to cotton growth.     

保护性耕作对土壤水分和小麦产量的影响

采用3种稻田保护性耕作栽培模式与传统栽培模式的定位试验,对成都平原稻田小麦季的土壤水分及产量进行了研究。结果表明:小麦全生育期,免耕覆盖处理的土壤含水率明显地高于翻耕覆盖处理,而翻耕不覆盖处理最差;小麦分蘖高峰期,覆盖处理的土壤含水率比不覆盖处理高17.7%～75.9%,免耕覆盖处理的土壤含水率比翻耕覆盖处理高12.7%～41.0%;免耕覆盖处理的小麦最高茎蘖数又比翻耕覆盖处理增加23.8%～72.3%,均极显著优于翻耕处理;覆盖处理的小麦产量比不覆盖处理增产6.3%～19.5%,免耕覆盖处理比翻耕覆盖处理增产3.2%～8.0%。稻田保护性耕作有利于提高成都平原区小麦产量。     

棉花调亏灌溉效应研究

盆栽试验研究棉花调亏灌溉效应结果表明 ,棉花苗期为水分亏缺最佳时期 ,土壤含水量应维持在田间持水量的 5 0 %～ 5 5 % ,吐絮期维持在田间持水量的 5 0 %左右 ,蕾期维持在田间持水量的 6 5 %～ 70 % ,花铃期是棉花生长关键期 ,其土壤含水量应维持在田间持水量的 75 %左右 ,适当降低土壤含水量有助于提高棉株蕾铃数量 ,可减少蕾铃脱落。     

调亏灌溉对棉花生长、生理及产量的影响

通过盆栽试验在棉花不同生育时期进行不同程度的调亏灌溉试验。结果表明,调亏灌溉对棉花株高、蕾铃脱落、成桃数等影响较显著;苗期和吐絮期重度水分亏缺、蕾铃期中度水分亏缺均有利于棉花产量的形成。棉花的光合速率和气孔阻力随土壤含水量变化的阈值约在14％土壤含水量水平,该阈值相当于田间持水量的60％～65％。合理的棉花调亏灌溉制度是苗期控制水分供应,土壤含水量维持在田间持水量的55％～60％;蕾期和花铃期是棉花的需水关键期,土壤含水量应分别保持在田间持水量的65％和70％左右;吐絮期应控制水分供应,土壤含水量维持在田间持水量的50％～55％。     

田间微集雨种植方式及播种行距对小麦产量和水分利用效率的影响

为高效利用天然降水资源, 提高自然降水水分利用效率, 在山西临汾采用随机区组设计方法研究了田间微集雨种植方式及其播种行距对小麦产量及水分利用效率的影响.结果表明: 集雨产流带覆盖面积与种植带面积比例为1:1.5和1:1的种植方式平均产量均较对照(露地种植)显著增产, 1:1.5、1:1和露地种植的播种行距分别以11.3 cm、15 cm和15 cm具有较好的增产效应; 1:1.5和1:1种植方式在拔节期的个体生物学性状株高、单株分蘖和单株绿叶数优于露地栽培; 1:1.5、1:1和露地栽培的水分利用效率分别为19.8 kg·mm-1·hm-2、17.4 kg·mm-1·hm-2、14.3 kg·mm-1·hm-2.该项研究同时明确了不同田间微集雨种植方式在各生育时段的土壤水分变化动态特征.     

Effect of tillage depth on physical properties of a tropical soil and on yield of maize, sorghum and cotton

Field experiments were carried out to study the effect of three tillage depths (5, 15 and 30 cm) on soil physical properties and on yield of maize (Zea mays), sorghum (Sorghum bicolor) and cotton (Gossypium hirsutum) on a ferruginous tropical soil. The increase in porosity due to deep tillage was only temporary and differences in water storage and movement were only noticeable during the early part of the rainy season. Deep tillage increased the yield of maize and cotton by about 10% but sorghum yield was not affected.     

保护性耕作对土壤物理特性及玉米产量的影响

保护性耕作措施是干旱区农田提高作物产量的新型耕作技术。为了探讨其区域适应性,在2004～2007年期间,以毛乌素沙地南缘的靖边县北部风沙区农田为研究对象,选用了免耕、秸秆覆盖、覆膜和传统翻耕(CK)4种措施,采用完全随机试验设计进行了田间定位试验研究。结果表明,秸秆覆盖和免耕地的地温在春播初期略比传统翻耕低0.1℃,但随后迅速回升,覆膜在玉米生长期都高于其他措施。耕作措施对播种前土壤容重没有显著影响,而对收获后土壤容重影响显著,与传统翻耕相比,免耕降低了表层土壤容重1.65%,但次层20～40 cm容重增加了1.8%。3种保护性耕作措施均增加了土壤含水量,顺序依次为秸秆覆盖>覆膜>免耕>翻耕,且在作物需水关键期免耕和秸秆覆盖下的土壤含水量相对稳定,保证作物需水,提高水分利用率,分别为8%、22.0%和13.3%。使作物分别增产4.44%、13.14%和19.26%。因此,保护性耕作在风沙区有利于改善农田土壤物理条件,提高作物产量,适于在风沙区推广。     

不同耕作方式对水稻产量和土壤肥力的影响

于2005～2006年在双季稻田研究了不同耕作方式对水稻生长、产量和土壤肥力的影响。结果表明:免耕抛秧水稻根干重低于翻耕移栽稻,根系绝大部分分布在表层土壤,根系活力比翻耕处理的高,分蘖时间比翻耕移栽的早而比翻耕抛秧的迟;每公顷有效穗数略低于翻耕抛秧而高于翻耕移栽,结实率高于翻耕处理。随着免耕次数的增加,各处理产量基本持平;免耕1年有利于土壤物理性质的改善,免耕有利于土壤养分在表层土壤富集。     

不同行距对冬小麦麦田蒸发、蒸散和产量的影响

为了研究不同行距对冬小麦田棵间蒸发、蒸散和产量的影响,于2002～2003年在中国科学院栾城农业生态实验站进行了试验。结果表明：不同行距处理对棵间蒸发的影响在不同的冬小麦生育时期表现不同,在4月份呈现显著性差异,在12月-3月之间,处理之间没有明显差异,在其它时期7.5 cm的行距处理与30 cm行距的处理呈显著性差异,15cm的处理与它们均没有明显的差异;在整个生育期内,7.5 cm的行距处理比15 cm和30 cm的行距处理分别减少棵间蒸发13.26和29.04 mm,蒸散量减少22.76 mm和51.88 mm;7.5 cm的行距处理比15 cm和30 cm的行距处理分别提高产量水分利用效率0.11 kg/m³和0.23 kg/m³。     

The effect of reduced tillage of an irrigated silty soil and of a mulch on seedling emergence, growth and yield of maize (Zea mays) harvested for silage

Maize was grown for 1 season as a row-crop on raised beds in a factorial experiment on reduced tillage. The effects of 2 passes of a spring-tined cultivator (Treatment C), of a small 70-mm wide rotary-hoe, ahead of the seeder (Treatment R) and of a mulch (Treatment M) on emergence, growth and yield of maize were determined. Treatment C produced a coarse tilth (41% aggregates > 20-mm diameter; 9% aggregates 0.5–2 mm) in the top 30 mm of pre-irrigated beds of a silty soil. Treatment R produced a fine seed-bed (4% aggregates > 20-mm diameter; 21% aggregates 0.5–2 mm), 70 mm wide and 30 mm deep, along each of the 2 sowing-lines. In the same pass, 2 rows of maize were sown at a depth of 25 mm into the wet soil.

In the mulched treatments (M), where 5 t ha⁻¹ of barley straw was applied after the crop was sown, to cover the bed, the water content around the seed (0–30-mm depth) over the first 9 days after the crop was sown was 29–74% higher than in the unmulched treatments (M₀). For example, 1 day after the crop was sown, the water content of soil around the seed was 21% in Treatment M, close to field capacity, and 14% in Treatment M₀. In Treatment M, the temperature around the seed (25-mm depth) at 15.00 h over the first 9 days after the crop was sown was almost always significantly lower than in Treatment M₀; for example, the maximum temperatures of Treatments M and M₀ were 32 and 41°C, respectively.

Either Treatment M or R, but not Treatment C hastened emergence of maize seedlings and increased percentage final emergence. There were no significant effects of any treatments on plant yield. However, there was a trend within Treatment M for either Treatments R or C to increase yields.