A straw mulch system to allow continuous wheat production in an arid climate

Cereal Cyst Nematode (CCN, Heterodera avenae Woll.) has been shown to be a devastating pest for wheat (Triticum aestivum L.) in dryland regions. Fallowing in the season preceding the cropping season has been hypothesized to sanitize the soil of CCN and allow wheat production. This paper explores management options that might allow the continuous production of wheat in these regions. In a 20-year study in the Negev, Israel, on a sandy loam, loessial, soil, it was found that in those seasons with high rainfall there was virtually no decrease in annual wheat yields for continuous crops as compared to biennial fallow yields obtained with the conventional wheat system. The hypothesis that high soil water content substantially alleviates the damage resulting from CCN infestation was confirmed in a pot study. A practical solution for maintaining high soil water content in the field was to leave a straw mulch on the soil surface to decrease soil evaporation. A chopper was added to a grain harvester to finely chop the straw so that it settles to the soil surface through the stubble, and a no-till drill was used for sowing through the straw. The straw-mulch system was shown to result in annual yields from continuous wheat that were equivalent to yields in alternate years with the conventional fallow wheat system, thereby doubling wheat production in this dryland region.     

Cereal cyst nematode effects on wheat water use,and on root and shoot growth

Wheat (Triticum aestivum L.) is grown in many arid regions using fallow management whereby no crop is grown in alternate cropping seasons. Although fallowing is important in increasing the availability of water and nitrogen to crops in many environments, experiments in Israel revealed that water carryover from the fallow season for wheat production was rare. This paper examines the possibility that improved water use, and improved root and shoot growth, result from soil sanitation of cereal cyst nematode (CCN, Heterodera avenae Woll.) in the fallow season. Pot experiments in controlled environments revealed a dramatic, negative effect of various populations of CCN on wheat root growth. The decrease in root growth was associated with decreased shoot growth and decreased rates of transpiration. Mechanical pruning of roots mimicked the effects of CCN infestation indicating that root pruning is probably the primary damage of CCN. In the field, dry weight yields of wheat were maintained even in continuous wheat management when a soil biocide was used to control CCN. It is proposed that the success of the fallow management is based on the fact that CCN cysts hatch in wet soil during rainy periods of the fallow year but fail to produce a new generation of cysts because no host plants are present.     

Simulated long-term effects of different soil management regimes on the water balance in the Loess Plateau, China

A soil management regime that improves water use efficiency (WUE) is urgently required to increase the sustainability of the winter wheat-summer fallow system in the Loess Plateau, China. However, the long-term partitioning of the water balance must be understood in order to evaluate the viability of possible soil management regimes. Therefore, an ecosystem model (CoupModel) was used to explore the effects on components of the water balance of five types of soil management regimes: conventional practice, wheat straw mulching, incorporation of high organic matter contents, compaction, and use of a harvested fallow crop. Three variants of the fallow crop approach were also considered, in which the crop was harvested 15, 30 and 45 days before sowing the wheat (designated Fallow-15d, Fallow-30d and Fallow-45d, respectively). Simulations were used to identify the relative magnitude of soil evaporation, wheat transpiration and deep percolation and to elucidate the temporal variability in these components for a selected location using climate records spanning 45 years. However, the soil management regime significantly influenced the magnitude of every component of the water balance (in terms of minimum, maximum and mean values) over the long periods considered. Consequently, wheat yield and WUE differed significantly among the simulated treatments. Mulching led to significantly lower soil evaporation, higher transpiration, and more frequent and extensive deep percolation than other regimes, thereby improving fallow efficiency (percentage of rainfall stored in the soil during the fallow period at the end of the fallow period), wheat yields and WUE. In contrast, soil compaction gave the opposite results, leading to the most unfavourable partitioning of the water balance reflected in the lowest wheat yield and WUE values of all the regimes. In 90% of the years no deep percolation occurred in the soil compaction simulations. Use of a fallow crop with optimal harvest timing (Fallow-30d) improved partitioning of the water balance (decreased soil evaporation) and did not significantly reduce wheat yield compared with conventional practice. High organic matter contents in the soil also had a positive influence on the water balance and improved wheat yield and WUE relative to conventional practice. Therefore, mulching appears to be the best management practice for the winter wheat-summer fallow system in the Loess Plateau, according to the simulations. Increasing soil organic matter may be the best option if mulching cannot be implemented. The ideal time for harvesting a fallow crop for use as green manure or fodder appears to be ca. 30 days before sowing the winter wheat.     

Effects of Crop Residue and Nitrogen Rates on Yield and Yield Components of Two Dryland Wheat (Triticum aestivum L.) Cultivars

Abstract

In most southern parts of Iran, wheat (Triticum aestivum L.) residues have been traditionally burned or removed; that is often criticized for soil organic and nutrient losses, reducing soil microbial activity and increasing CO₂ emission. A 2-years (2005?2007) field study was carried out at the College of Agriculture, Shiraz University, Shiraz, Iran, to evaluate the influence of crop residues management and nitrogen (N) rates on dryland wheat. The experiment was conducted as strip split plot with four replications. Horizontal plots were three crop residues rates (0, 500 and 1000 kg ha-¹), vertical plots consisted of two dryland current wheat cultivars (CVs) (Azar 2 and Nicknejad), and sub-plots were three N rates (0, 35, and 70 kg N ha-¹). Increasing crop residue rates increased soil organic carbon. Number of spike per plant, grains per spike, grains per plant and 1000-grain weight of both CVs significantly increased with increased N and residue rates in both years. The lowest grain yield was obtained from 1000 kg ha-¹ residue incorporation without N application showing the soil N imbalance. The optimum crop growth and the highest grain yield was achieved from the highest crop residues and N rates, indicating that the most reliable system for dryland wheat production in the region is complete residues incorporation into the soil following disking, seeding with chisel seeder and application of 70 kg N ha-¹.     

Simulation analysis of lucerne–wheat crop rotation on the Loess Plateau of Northern China

The Agricultural Production System Simulator (APSIM) was parameterised and tested against datasets from two field experiments being conducted on Heilu soil at the Qingyang Research Station, Gansu, China as to investigate long-term lucerne productivity and management options of reducing impact of lucerne on winter wheat yield in a lucerne–wheat rotation system. With minimal parameterisation and configuration of the APSIM-Lucerne module, APSIM was able to simulate phenological development and seasonal growth of winter-dormant lucerne cultivar, Longdong compared with the observed data. Flowering date was accurately simulated using the established relationship between accumulated thermal time and mean photoperiod. After the APSIM-Lucerne module was configured for the seasonal variation in RUE (radiation use efficiency), the model simulated lucerne seasonal biomass production over three growing seasons in the continuous lucerne treatment with a root mean squared deviation (RMSD) of 1132 kg/ha (30% of the mean observed biomass). In the treatment where lucerne was removed in August 2001 and two winter wheat crops were sown and harvested in 2001/2002 and 2002/2003 growing seasons, APSIM simulated winter wheat crop biomass in both growing seasons with a RMSD of 1420 kg/ha (20% of the mean observed crop biomass). Wheat grain yield was simulated with a RMSD of 918 kg/ha (27% of the mean observed grain yield). Using measurements of drained upper limit (DUL) and lower limit (LL), and standard soil evaporation and runoff parameters, the model was able to simulate soil water dynamics and water use by lucerne in the lucerne-fallow, continuous lucerne and lucerne–wheat treatments.     

Effects of tillage,crop rotation and nitrogen fertilization on wheat-grain quality grown under rainfed Mediterranean conditions

The grain quality of wheat is influenced by the protein content, which in turn depends on environmental conditions and cropping practices. We carried out a 3-year field study in a rainfed Mediterranean region on the effects of tillage, crop rotation and nitrogen fertilization on the grain quality of hard red spring wheat (Triticum aestivum) in terms of protein content, test weight and alveogram indices. Tillage treatments were no tillage (NT) and conventional tillage (CT). Crop rotations were wheat–sunflower (Helianthus annus L.) (WS), wheat–chickpea (Cicer arietinum L.) (WCP), wheat–fababean (Vicia faba L.) (WFB), wheat–fallow (WF) and continuous wheat (CW). Fertilizer nitrogen was used at three different rates: 50, 100 and 150 kg N ha⁻¹. A split–split plot design with four replicates was used. Grain protein content was found to be inversely proportional to rainfall during the growing season. The tillage method was also found to affect grain protein content, test weight and some grain quality indices. Through its effect on moisture and nitrate in the soil. The crop rotations that included a legume (WCP and WFB) had marked effects on wheat quality. The increased grain protein content and resulted in improved rheological properties of the dough (viz. a higher alveogram index and a more balanced tenacity/extensibility ratio). However, no differences due to N dilution in the plant were observed in the wettest year studied, which was also the highest yielding. Increasing the fertilizer N rate increased the grain protein content; this variable had the most marked influence on grain quality indices, though in the year that gave the highest yield the N dilution effect was observed. The many significant interactions among experimental variables reveal a close relationship among grain yield, protein content, grain quality and the wheat growth conditions. Specifically, the amount of rainfall and its distribution in the growing season strongly influenced N availability and uptake by the crop, as well as wheat-grain quality indices.     

Cereal–legume rotations in a Mediterranean environment: biomass and yield production

The effects of various crop rotations on the biomass and yield of barley (Hordeum vulgare L.), faba bean (Vicia faba L.), and pea (Pisum sativum L.) grown under Mediterranean conditions were studied during three growing seasons in the semiarid Spanish Central Plateau. The treatments comprised six crop sequences: barley monoculture, fallow–barley (currently used in the area), faba bean–barley, pea–barley, fallow–barley–faba bean, and fallow–barley–pea. The fallow was of 16-month duration. The site is representative of cultivated areas of the Plateau, and the soil has a loam texture. Results concentrate on barley as the main crop. Season distribution of rainfall restricted the effectiveness of the management practices and in consequence there were few differences between rotations. Barley had greater biomass and yield after fallow than after other crops but significant differences were dependent on year. Legumes, an alternative to fallow, increased land use, permitted alternative weed control measures, and reduced the need for fertiliser. The intensification of the fallow–barley cropping system is best achieved by reducing the frequency of fallow and including other crops of relatively small biomass production, thereby minimising the impact on yield of the succeeding barley crop.     

夏闲期施肥与覆盖处理对旱地冬小麦产量和土壤水分利用的影响

为给旱地夏闲期管理提供参考依据,采用大田试验,研究了夏闲期施肥与覆盖处理对旱地冬小麦土壤储水量、产量及水分利用效率的影响。结果表明,夏闲期施肥可明显提高播前0~100、100~200 cm土层储水量,增加了冬小麦穗数、籽粒产量和水分利用效率;不论施肥与否,地膜覆盖与纸覆盖均可提高播前底墒,增加小麦穗数和穗粒数,显著提高籽粒产量和水分利用效率,且地膜覆盖处理效果优于纸覆盖;施肥可增进覆盖的保水、增产及高效用水的作用。因此,旱地夏闲期可通过施肥与覆盖技术改善土壤水分状况,为旱地秋播作物高产创造条件。     

Effects of transition season management on soil N dynamics and system N balances in rice–wheat rotations of Nepal

In the low-input rice–wheat production systems of Nepal, the N nutrition of both crops is largely based on the supply from soil pools. Declining yield trends call for management interventions aiming at the avoidance of native soil N losses. A field study was conducted at two sites in the lowland and the upper mid-hills of Nepal with contrasting temperature regimes and durations of the dry-to-wet season transition period between the harvest of wheat and the transplanting of lowland rice. Technical options included the return of the straw of the preceding wheat crop, the cultivation of short-cycled crops during the transition season, and combinations of both. Dynamics of soil N_min, nitrate leaching, nitrous oxide emissions, and crop N uptake were studied throughout the year between 2004 and 2005 and partial N balances of the cropping systems were established. In the traditional system (bare fallow between wheat and rice) a large accumulation of soil nitrate N and its subsequent disappearance upon soil saturation occurred during the transition season. This nitrate loss was associated with nitrate leaching (6.3 and 12.8 kg ha⁻¹ at the low and high altitude sites, respectively) and peaks of nitrous oxide emissions (120 and 480 mg m⁻² h⁻¹ at the low and high altitude sites, respectively). Incorporation of wheat straw at 3 Mg ha⁻¹ and/or cultivation of a nitrate catch crop during the transition season significantly reduced the build up of soil nitrate and subsequent N losses at the low altitude site. At the high altitude site, cumulative grain yields increased from 2.35 Mg ha⁻¹ with bare fallow during the transition season to 3.44 Mg ha⁻¹ when wheat straw was incorporated. At the low altitude site, the cumulative yield significantly increased from 2.85 Mg ha⁻¹ (bare fallow) to between 3.63 and 6.63 Mg ha⁻¹, depending on the transition season option applied. Irrespective of the site and the land use option applied during the transition season, systems N balances remained largely negative, ranging from −37 to −84 kg N ha⁻¹. We conclude that despite reduced N losses and increased grain yields the proposed options need to be complemented with additional N inputs to sustain long-term productivity.     

Modeling responses of dryland spring triticale,proso millet and foxtail millet to initial soil water in the High Plains

Dryland farming strategies in the High Plains must make efficient use of limited and variable precipitation and stored water in the soil profile for stable and sustainable farm productivity. Current research efforts focus on replacing summer fallow in the region with more profitable and environmentally sustainable spring and summer crops. In the absence of reliable precipitation forecasts for the crop growing season, farmers rely mainly upon knowledge of plant available water (PAW) in the soil profile at planting for making crop choice decisions. To develop a decision support strategy for crop selection based on initial PAW, experiments were conducted with spring triticale (XTiticosecale Wittmack), proso millet (Panicum miliaceum L.), and foxtail millet (Setaria italica L. Beauv.) under artificially controlled Low, Medium, and High initial PAW levels during 2004 and 2005 at Akron, Colorado, and Sidney, Nebraska. The objectives of this study were to adapt an existing cropping systems model for the simulation of triticale and millet and to evaluate simulations from the adapted model by comparing results with field data collected under varying initial PAW conditions. The Root Zone Water Quality Model with DSSAT v4.0 crop growth modules (RZWQM2) was used. Specifically, the Cropping System Model (CSM)–CERES–Wheat module was adapted for simulating triticale, and CSM–CERES–Sorghum (v4.0) module was adapted for simulating proso millet and foxtail millet. Soil water, leaf area index, grain yield, and biomass data for the highest PAW treatment from one crop season for each of the three crops were used to adapt and calibrate the crop modules. The models were then evaluated with data from the remaining PAW treatments. The proso millet module was further tested with four years of data from a crop rotation experiment at Akron from 2003 to 2006. Simulation results indicated that the adapted and calibrated crop modules have the potential to simulate these new crops under a range of varying water availability conditions. Consequently, these models can aid in the development of decision support tools for the season-to-season management of these summer fallow replacement crops under dryland conditions in semi-arid environments.     

Evaluating decision rules for dryland rotation crop selection

No-till dryland winter wheat (Triticum aestivum L.)-fallow systems in the central Great Plains have more water available for crop production than the traditional conventionally tilled winter wheat-fallow systems because of greater precipitation storage efficiency. That additional water is used most efficiently when a crop is present to transpire the water, and crop yields respond positively to increases in available soil water. The objective of this study was to evaluate yield, water use efficiency (WUE), precipitation use efficiency (PUE), and net returns of cropping systems where crop choice was based on established crop responses to water use while incorporating a grass/broadleaf rotation. Available soil water at planting was measured at several decision points each year and combined with three levels of expected growing season precipitation (70, 100, 130% of average) to provide input data for water use/yield production functions for seven grain crops and three forage crops. The predicted yields from those production functions were compared against established yield thresholds for each crop, and crops were retained for further consideration if the threshold yield was exceeded. Crop choice was then narrowed by following a rule which rotated summer crops (crops planted in the spring with most of their growth occurring during summer months) with winter crops (crops planted in the fall with most of their growth occurring during the next spring) and also rotating grasses with broadleaf crops. Yields, WUE, PUE, value-basis precipitation use efficiency ($PUE), gross receipts, and net returns from the four opportunity cropping (OC) selection schemes were compared with the same quantities from four set rotations [wheat-fallow (conventional till), (WF (CT)); wheat-fallow (no-till), (WF (NT)); wheat–corn (Zea mays L.)-fallow (no-till), (WCF); wheat–millet (Panicum miliaceum L.) (no-till), (WM)]. Water use efficiency was greater for three of the OC selection schemes than for any of the four set rotations. Precipitation was used more efficiently using two of the OC selection schemes than using any of the four set rotations. Of the four OC cropping decision methods, net returns were greatest for the method that assumed average growing season precipitation and allowed selection from all possible crop choices. The net returns from this system were not different from net returns from WF (CT) and WF (NT). Cropping frequency can be effectively increased in dryland cropping systems by use of crop selection rules based on water use/yield production functions, measured available soil water, and expected precipitation.     

休闲期覆膜与施氮量对旱地小麦水氮利用效率和籽粒产量的影响

为探寻旱地小麦休闲期覆盖下的适宜施氮量,在旱地小麦休闲期覆盖与不覆盖条件下,分别设置75、150和225kg·hm-2三个施氮量,分析了休闲期覆盖配施氮肥对旱地小麦水氮利用效率和籽粒产量的影响。结果表明,休闲期覆盖显著提高播种至孕穗期0~300cm土壤蓄水量,其中播种期土壤水分增加70~81mm,其蓄水保墒效果可延续至孕穗期,进而提高了小麦产量和水分利用效率。休闲期覆盖促进了小麦植株对氮素的吸收和积累,增加了植株花前氮素转运量、花后氮素积累量以及籽粒氮素积累量,提高了氮素收获指数和氮素生产效率。休闲期覆盖配施氮素150kg·hm-2时,蓄水、增产和水分高效利用、氮素积累与转运的效果最好。     

Analysis of yield-attributing traits for high-yielding wheat lines in southwestern Japan

Development of wheat cultivars that achieve high yields despite the short growing season is essential for increasing wheat production in southwestern Japan. The objectives of this study were to assess the genetic progress in grain yield and to clarify yield-attributing traits of high-yielding wheat lines in southwestern Japan. We conducted field experiments for two growing seasons (2012–2013 and 2013–2014) using three commercial wheat cultivars (Shiroganekomugi, Chikugoizumi, and Iwainodaichi) and four high-yielding wheat lines including Hakei W1380 developed in southwestern Japan. In an ancillary field experiment, we compared a commercial cultivar, Shiroganekomugi, and a high-yielding line, Hakei W1380, in the 2014–2015 season. Across the two seasons, grain yield of high-yielding lines was generally higher than commercial cultivars. Hakei W1380 achieved the highest grain yield across the two seasons, and successfully produced more than 900 g m^?2 in the 2013–2014 season. Correlation analysis showed that recent yield progress of wheat lines in southwestern Japan was derived from enhanced biomass production and grain number m^?2. Larger numbers of grains m^?2 in high-yielding lines than in commercial cultivars were associated with higher crop growth rate at the pre-anthesis stage, and therefore higher spike dry weight m^?2 at anthesis. Genotypic differences in crop growth rate from jointing to anthesis resulted mainly from differences in leaf area index. These results indicate that further improvements in grain yield in southwestern Japan could be achieved by increasing the amount of radiation intercepted at the pre-anthesis stage and grain number m^?2.     

Effects of Soil Type,Vertical Root Distribution and Precipitation on Grain Yield of Winter Wheat

Abstract

In Abashiri in eastern Hokkaido, Japan, grain yields of winter wheat (Triticum aestivum L. cv. Hokushin) in the western area, with umbric andosol or dystric cambisol soil types, are lower and unstable compared to those in the eastern area, with mostly haplic andosol soil type. The aim of this study was to evaluate yield differences between the eastern and western areas. The vertical root distribution of wheat plants was examined over two seasons in farmers’ fields in both areas by a wall profile method. Plants grown in the western area had shallower root systems than those grown in the eastern area. Poor soil porosity and high soil penetration resistance suppressed the vertical distribution of root systems in umbric andosol and dystric cambisol. Grain yields were not always correlated with the amount and distribution of the root system. Grain yield in the 2004/2005 season was not correlated with root depth index, whereas it was positively correlated in the 2005/2006 season. During the period from heading to maturity (mid June to late July) over the two seasons, grain yield was associated with precipitation more than with temperature and total solar radiation. In the 2005/2006 season, during the late growing stage of wheat, precipitation was extremely low and soils were very dry. The difference in grain yield between the eastern and western areas was significant and negatively related to precipitation during the period from heading to maturity. Significant correlations of yield with sunshine duration and solar radiation from the heading stage to maturity were observed only on haplic andosol. The results suggest that the major factor controlling yearly changes in the difference in grain yield of winter wheat between the eastern and western areas is the difference in photosynthetic ability, which is based on rooting depth and water supply in response to solar radiation during the late growing stage.     

休闲期耕作对旱地小麦籽粒蛋白质形成及其相关酶活性的影响

为给旱地小麦高产优质栽培提供理论依据,通过大田试验研究了旱地小麦休闲期不同时间深翻、深松对0～300 cm土壤蓄水量、小麦籽粒蛋白质形成及其与氮代谢相关酶活性关系的影响.结果表明,休闲期深翻或深松均可提高旱地小麦播前0～300 cm土壤蓄水量,且欠水年效果明显,以前茬小麦收获后45 d深翻效果较好.休闲期耕作均显著提高了小麦蛋白质产量.耕作时间对籽粒蛋白质含量的影响因降雨年型不同而异,欠水年的休闲期耕作均显著降低了籽粒蛋白质含量;丰水年在麦收后15d耕作显著降低了籽粒蛋白质含量,而麦收后45 d耕作则显著提高了籽粒蛋白质含量,尤其显著提高了醇溶蛋白和麦谷蛋白含量,从而改善了品质.此外,丰水年麦收后45 d耕作可提高花后旗叶和籽粒谷氨酰胺合成酶(GS)活性、旗叶和籽粒谷氨酸合成酶(GOGAT)活性,降低花后旗叶和籽粒谷氨酸脱氢酶(GDH)活性;籽粒蛋白质的累积在麦收后15d耕作条件下与籽粒GDH活性关系密切,而麦收后45 d耕作条件下与旗叶GS和GOGAT活性相关性较大.总之,旱地小麦休闲期耕作在不同降雨年型下均可起到良好的蓄水保墒作用,且欠水年效果较明显;耕作时间对土壤水分、小麦氮代谢酶活性、籽粒蛋白质及其组分含量具有较大的调控效应,休闲期雨后耕作有利于籽粒蛋白质形成,且深翻效果较好.     

休闲期不同耕作模式对旱地麦田土壤水分、养分及产量的影响

为探索适宜晋南旱地小麦高效生产的耕作模式,以晋麦92为试验材料,设置休闲期深翻/深翻、深松/深翻、深松/深松、常规耕作(对照)4个耕作模式,研究其对土壤水分及养分、作物生长和水分利用效率的影响。结果表明,深翻/深翻、深松/深翻、深松/深松模式较对照休闲末期3m内土壤蓄水量和土壤蓄水效率显著提高,土壤蓄水效率提高达52.5%~91.3%,以深松/深松模式较好;越冬-孕穗期3m内土壤蓄水量提高,且深松/深松模式与对照差异显著;各生育时期单株干物质积累量提高,且越冬-拔节期深松/深松、深松/深翻模式与对照差异显著,孕穗-成熟期各耕作模式与对照差异均显著;穗数、千粒重、产量和水分利用效率显著提高,其中穗数提高22.7%~29.9%,水分利用效率提高15.1%~21.6%,产量提高39.4%~60.3%,以深松/深松模式较好;收获后0~40cm土层土壤有机质平均含量提高2.5%~8.7%,速效磷含量提高11.1%~34.4%,碱解氮含量提高5.1%~20.2%,以深松/深松模式较好。总之,深翻/深翻、深松/深翻、深松/深松模式均能提高土壤蓄水保墒能力,改善养分供应状况,有利于促进小麦干物质积累,最终提高产量和水分利用效率,以深松/深松模式最佳。     

秸秆带状覆盖对旱地冬小麦产量及土壤水分的影响

为探讨西北半干旱雨养条件下秸秆带状覆盖麦田水分利用特征和增产效果,通过田间试验,以露地条播为对照(CK),研究了3种不同覆盖处理[秸秆带状覆盖常规条播(SM1)、秸秆带状覆盖宽幅条播(SM2)和全膜覆土穴播(PM)]对旱地冬小麦田土壤含水量、小麦产量和水分利用效率的影响。结果表明,秸秆带状覆盖和全膜覆土穴播均可显著改善小麦全生育期0~20cm以及开花前20~90cm土壤墒情,但开花后20~90cm以及全生育期90~200cm土壤墒情普遍不如CK。3种覆盖处理均能促进冬小麦对土壤贮水的利用,显著提高开花至成熟阶段的耗水量及其占总耗水量的比例。秸秆带状覆盖和全膜覆土穴播生育期耗水量分别比CK增加4.6%和7.6%。秸秆带状覆盖在孕穗前0~200cm土壤墒情与全膜覆土穴播无显著差异,孕穗期开始则好于全膜覆土穴播;全膜覆土穴播0~200cm土壤贮水消耗量显著高于秸秆带状覆盖,而开花至成熟阶段的耗水量及其占总耗水量的比例则略低于秸秆带状覆盖。3种覆盖处理均显著提高产量和水分利用效率,PM、SM1和SM2较CK分别增产36.8%、29.7%和27.5%,水分利用效率分别提高27.3%、23.9%和22.7%。产量与生育期耗水量呈显著正相关(r=0.97*)。覆盖处理中,全膜覆土穴播产量虽最高,但从产量、水分利用效率和经济效益角度综合考虑,秸秆带状覆盖优于全膜覆土穴播。因此认为,秸秆带状覆盖是一种更加高产高效、适宜在西北半干旱雨养区推广的覆盖种植方式。     

Rice establishment method affects nitrogen use and crop production of rice–legume systems in drought-prone eastern India

The inclusion of grain legumes in rainfed lowland rice farming systems provides an opportunity to increase food production, household income, and human nutrition of impoverished rice farmers in Asia. We examined the effect of rice establishment method on the performance of wet season rice (Oryza sativa L.) and post-rice crops of either chickpea (Cicer arietinum L.) or moong [Vigna radiata (L.) Wilczek] on an Udic Haplustalf in the drought-prone, rainfed lowlands of eastern India. Rice was either direct seeded in lines on moist soil immediately after the onset of wet season rain or transplanted after sufficient rainwater accumulated for soil submergence. Crop establishment method had no effect on rice performance in a season (2001) with normal rainfall. In a drought season (2002), direct seeding resulted in mean rice grain yield of 2.3 t ha⁻¹, whereas the transplanted rice crop failed. The agronomic efficiency of N fertilizer applied to direct-seeded rice was comparable for the 2 years (18 and 24 kg grain per kg N applied). Topsoil inorganic N was markedly higher following chickpea and moong than following a post-rice fallow. Direct-seeded rice had higher yield and accumulation of N following a post-rice legume than following fallow, but transplanted rice derived no such benefit from the legume. Direct-seeded rice was established 1–2 months before transplanted rice, and direct-seeded rice matured before transplanted rice by 8 days in the favorable season and by 26 days in the drought season. The soil nitrate present after legumes and fallow rapidly disappeared, presumably by denitrification, following the onset of rains and soil flooding prior to transplanting. A portion of this accumulated soil nitrate was taken up by the direct-seeded rice before it could be lost. But transplanted rice did not benefit from this inorganic N derived from legumes because virtually all soil nitrate was lost before transplanting. Direct seeding of rice ensured better use of residual and applied N, reduced risk due to drought, and favored intensification with post-rice legumes in drought-prone lowland systems.     

Integrating the effects of climate and plant available soil water holding capacity on wheat yield

In the Mediterranean farming systems of the Western Australian wheatbelt, crop yields are influenced primarily by the amount and distribution of rainfall and the soil's capacity to hold moisture. The wheatbelt's growing season rainfall varies in the range of 200–400 mm (average) and the plant available water holding capacity (PAWC) of soils is generally in the 40–140 mm range. The grain yield of wheat is sensitive to this combination of small rainfall and small storage capacity.In this study, we explore the relationship between yield and PAWC using a combination of simulation modelling and analysis of field data. Crop yields and soil properties were monitored in detail at 17 locations (PAWCs 43–131 mm) across six seasons (1997–2005). Crop yields were also simulated using the APSIM crop simulator (RMSE = 311 kg/ha) to evaluate the long-term relationship between crop yield and plant available water capacity using 106 years of historical climate data.The relationship between crop yield and PAWC varied with season, and two important factors emerged: (1) for PAWC < 65 mm, there was a linear relationship with crop yields that ranged from 17 kg/ha/mm to 58 kg/ha/mm of PAWC across seasons; (2) for PAWC 65–131 mm the crop yield response to PAWC ranged from 11.5 kg/ha/mm in 45% of seasons to no response.The impact of PAWC on crop yield was reduced in seasons with late rainfall, and magnified in seasons with reduced rainfall late in the growing season. Six distinct season types with different yield–PAWC relationships are identified and season-specific management strategies that exploit within-field variation in PAWC are developed to manage the spatial variation of PAWC in a field.     

Improving Rice-Based Cropping Pattern Through Soil Moisture and Integrated Nutrient Management in Mid-Tropical Plain Zone of Tripura,India

An experiment was conducted in three fallow paddy fields situated on the mid-tropical plain zone of a northeastern Indian state(Tripura) to provide rice fallow management options using leftover soil moisture and nutrients. The three experimental fields were managed by growing rice under the system of rice intensification as the rainy season crop and then groundnut, lentil, rapeseed and potato as the post-rainy season crops. Fertilization under the integrated nutrient management system and lifesaving irrigation at critical stages of each post-rainy season crop were provided. Results showed that the field water use efficiency values were 5.93, 2.39, 2.37 and 59.76 kg/(hm2·mm) and that the yield of these crops increased by approximately 20%, 34%, 40% and 20% after applying two lifesaving irrigations in groundnut, lentil, rapeseed and potato, respectively. Therefore, fallow paddy field can provide possible profitable crops during the post-rainy season by utilizing the residual moisture and minimum supplemental irrigation under improved nutrient management practices.