Effectiveness of Sulphuric Acid and Gypsum for the Reclamation of a Calcareous Saline-Sodic Soil Under Four Crop Rotations

As a low‐cost strategy, the cultivation of certain salt‐tolerant crop species on calcareous saline‐sodic soils, i.e. phytoreclamation, has enjoyed great attention in recent years. A lysimeter study was carried out to evaluate whether a phytoreclamation approach alone, or in combination with some booster dose of either gypsum or sulphuric acid, is sufficient to reclaim a calcareous, moderately saline‐sodic soil. Four crop rotations, rice (Oryza sativa L.)–wheat (Triticum aestivum L.)–sesbania (Sesbania aculeata L.); rice–berseem (Trifolium alexandrinum L.); Kallar grass (Leptochloa fusca L.)–alfalfa (Medicago sativa L.) and sesbania–berseem were tested against three treatments: (T₁) control, (T₂) sulphuric acid application 25 % of soil gypsum requirement (SGR), and (T₃) application of gypsum 25 % SGR. To decrease the sodium adsorption ratio of the saline‐sodic soil well below the threshold level, especially from deeper depth, a booster dose of gypsum or sulphuric acid 25 % SGR was quite effective. Rice–berseem and Kallar grass–alfalfa rotations were more promising in combination with inorganic amendments than the rest of the rotations. The study also suggests that better yields of wheat and rice crops can be obtained with the application of inorganic amendments like gypsum or sulphuric acid. However, Kallar grass yield was somewhat suppressed with these amendments.     

Effect of Gypsum Application on Long Term Changes in Soil Properties and Crop Growth in Sodic Soils under Field Conditions

In a field study, conducted on farmer's waste sodic soils, Aquic Natrustalf, 12.5 t/ha gypsum was surface mixed. Effect of gypsum application on soil properties and crop yields of rice and wheat grown in succession was evaluated after one to five years of gypsum application. The results showed that soil pH, electrical conductivity, calcium carbonate and soil dispersion decreased, whereas organic carbon, hydraulic conductivity, water infiltration and storage increased considerably after five years of gypsum application. In the initial years the improvement in soil properties was more in the surface layers and extended to lower layers slowly in the following years. Average grain yields of rice and wheat in the first year were 4.2 and 1.8 t/ha, respectively. The yields further increased to 6.1 and 2.5 t/ha in the 5th year, but the yields were lower than the yields obtained in research experiment. Relationships between wheat grain yield and pH of 0–15 and 15–30 cm layers were established. Wheat yield reduced by 45 percent when pH of 0–15 cm layer increased from 9.0 to 9.5. The sodicity of sub soil was still too high to permit the cultivation of deep rooted crops even after five years of gypsum application. Normal crop production is possible in these sodic soils, given sufficient time to reduce the sub soil sodicity.     

Water Use and Yield of Wheat under Unmulched and Mulched Conditions in Laterite Soil of the Indian Sub-continent

A held experiment was conducted during three winter seasons on West Bengal laterite soil to study the effect of irrigation and paddy straw mulch on water consumption. Water use efficiency and yield of wheat are reported. Both irrigation and mulch increased wheat yield significantly; there was also significant interaction between irrigation and straw mulch application: three irrigations combined with mulch resulted in 21.6 q ha^-1 wheat grain yield compared with 17.5 q ha^-1 for three irrigations without mulch. Mulch consistently increased irrigation response. Both irrigation and mulch increased water consumption and water use efficiency of the wheat crop. To compare the two irrigation treatments, irrigation at crown root initiation followed up by at flowering stage gave higher values of water use efficiency as well as higher grain yield than that of irrigation applied at panicle stage followed by at crown root initiation.     

不同水肥运筹对再生季稻根际土壤酶活性及微生物功能多样性的影响

再生季水、肥管理措施是再生稻尤其是机收中低留桩再生稻获得高产稳产的一项关键措施,明确再生季合理的水肥运筹对提高机收中低留桩再生稻低节位再生芽的萌发成穗具有重要意义。本文以杂交籼稻泸优明占为材料,通过设置再生季分蘖期3个不同水肥处理盆栽试验,即淹水灌溉不施用促苗肥(S处理)、干湿交替灌溉不施用促苗肥(G处理)和干湿交替灌溉施用促苗肥(GN处理),研究不同水肥运筹对再生季稻腋芽、产量、根际土壤酶活性及微生物功能多样性的影响。结果表明,再生季稻不同水肥处理对根际氧化还原电位和根际土壤酶有显著影响,处理后10 d,与S处理相比,G处理可以显著提高根际土壤的氧化还原电位和根际土壤多酚氧化酶、过氧化物酶、磷酸单酯酶、过氧化氢酶活性,与G处理相比,GN处理可显著提高根际土壤多酚氧化酶、过氧化物酶、脲酶、蔗糖酶、磷酸单酯酶、过氧化氢酶活性。不同水肥调控下再生季稻根际土壤微生物对碳源的利用程度和碳源代谢的多样性差异显著,处理后10 d,GN处理和G处理根际微生物对6类碳源的利用程度显著高于S处理,GN处理根际土壤微生物对氨基酸、酚酸、羧酸类碳源的利用程度显著高于G处理。GN处理和G处理的根系伤流量分别比S处理的提高27.27%和14.84%,再生季分蘖数和产量分别比S处理的提高102.50%~111.11%、42.50%~44.44%和91.41%~108.72%、37.93%~40.94%。由此可见,再生季采用干湿交替灌溉或施用促苗肥均可提高根际土壤酶活性,促进再生季稻根际土壤微生物对碳源的利用程度和代谢多样性,从而有利于根际土壤有机质的氧化和腐殖质的形成及增加根际土壤中养分的有效性,促进再生季新根的形成和腋芽的萌发。采用干湿交替灌溉耦合促苗肥对再生季稻的促控效果是最佳的。     

Drip Irrigation Frequency: The Effects and Their Interaction with Nitrogen Fertilization on Sandy Soil Water Distribution, Maize Yield and Water Use Efficiency Under Egyptian Conditions

Irrigation frequency is one of the most important factors in drip irrigation scheduling that affects the soil water regime, the water and fertilization use efficiency and the crop yield, although the same quantity of water is applied. Therefore, field experiments were conducted for 2 years in the summer season of 2005 and 2006 on sandy soils to investigate the effects of irrigation frequency and their interaction with nitrogen fertilization on water distribution, grain yield, yield components and water use efficiency (WUE) of two white grain maize hybrids (Zea mays L.). The experiment was conducted by using a randomized complete block split‐split plot design, with four irrigation frequencies (once every 2, 3, 4 and 5 days), two nitrogen levels (190 and 380 kg N ha^?1), and two maize hybrids (three‐way cross 310 and single cross 10) as the main‐plot, split‐plot, and split‐split plot treatments respectively. The results indicate that drip irrigation frequency did affect soil water content and retained soil water, depending on soil depth. Grain yield with the application of 190 kg N ha^?1 was not statistically different from that at 380 kg N ha^?1 at the irrigation frequency once every 5 days. However, the application of 190 kg N ha^?1 resulted in a significant yield reduction of 25 %, 18 % and 9 % in 2005 and 20 %, 13 % and 6 % in 2006 compared with 380 kg N ha^?1 at the irrigation frequencies once every 2, 3 and 4 days respectively. The response function between yield components and irrigation frequency treatments was quadratic in both growing seasons except for 100‐grain weight, where the function was linear. WUE increased with increasing irrigation frequency and nitrogen levels, and reached the maximum values at once every 2 and 3 days and at 380 kg N ha^?1. In order to improve the WUE and grain yield for drip‐irrigated maize in sandy soils, it is recommended that irrigation frequency should be once every 2 or 3 days at the investigated nitrogen levels of 380 kg N ha^?1 regardless of maize varieties. However, further optimization with a reduced nitrogen application rate should be aimed at and will have to be investigated.     

灌溉和种植模式对冬小麦播前土壤含水量的消耗及水分利用效率的影响

为探讨华北平原地区冬小麦节水栽培的生产措施,2004-2006年,以冬小麦品种8049为试验材料,在大田4种灌溉条件下,研究了等行距平作、宽窄行平作、沟播和垄作4种种植模式对播前土壤含水量消耗及冬小麦耗水量、产量和水分利用效率的影响。结果表明,与等行距平作相比,另3种模式增加了播前土壤含水量的消耗,其耗水量显著提高,尤以沟播模式30 cm以下播前土壤含水量的消耗最为明显。和等行距平作相比,在灌拔节水+抽穗水和灌拔节水+抽穗水+灌浆水条件下,沟播模式显著提高冬小麦产量;而垄作模式的产量没有显著提高。在灌拔节水或灌拔节水+抽穗水条件下,沟播种植模式的水分利用效率显著高于其他3种种植模式。在本试验条件下,沟播种植结合灌拔节水或灌拔节水+抽穗水是一种值得推广的节水种植模式。     

Analysis of Water Supply of Plants Under Saline Soil Conditions and Conclusions for Research on Crop Salt Tolerance

Abstract In the dry areas of the world there is an increasing pressure to apply low quality brackish waters for plant irrigation (agriculture, horticulture, landscape greening). Consequently there is a demand to improve salt tolerance of conventional crops and to develop adequate irrigation techniques too. The efforts in the past decades to approach the understanding of salt stress mechanism by focusing on biochemical and physiological research were disappointing with respect to progress for crop growth and yields under saline soil conditions. However, it is generally agreed by all disciplines involved in research for crop salt tolerance that under saline soils conditions the reduced water supply of crops is the most critical growth factor. The paper presents some model calculations and field investigations that demonstrate the effect of root water uptake on the salinity of the root surrounding soil fraction (rhizospheric soil). It is shown that root hair length and rhizospheric soil volumes are factors most relevant for understanding crop salt tolerance, when growing in soils. It is postulated that short root hairs contribute to a lower salt tolerance (onions), whereas long root hairs enhance water uptake from saline soils and crop salt tolerance (rape). As interactions between roots and soil contribute to the salt tolerance of crops under field conditions, it is doubtful that selection for salt tolerant varieties and breeding for salt tolerance under conditions of water and flow culture experiments is very efficient. Breeding for more salt-tolerant crops and brackish irrigation techniques should consider root morphology and soil/root contact zone.     

Soil Organic Carbon Build-up and Dynamics in Rice–Rice Cropping Systems

Intensive irrigated rice system is the most important food production system in the world. Continued population growth necessitates increased rice production to meet the increased need of food production through increased rice productivity to ensure food security. In contrast, the recent slowdown in yield growth in intensive irrigated rice‐based cropping systems as a result of deterioration of soil health and decline in productivity level is a serious cause for concern. The objective of this research was to investigate the soil organic carbon (SOC) build‐up and its dynamics in rice–rice cropping system by including a green manure (GM) crop Sesbania rostrata Berm. either during fallow and/or intercrop at 4 : 1 ratio as additive series without changing rice geometry. The results revealed that there is a gradual build‐up of SOC when S. rostrata included and in situ incorporated at flowering stage as a basic means of improving soil quality in rice–rice cropping system. Further, the soil organic matter fractions viz. humic acid and fulvic acid were also improved in all GM‐incorporated systems. In general, the proportion of fulvic acid was higher than humic acid. Cropping system involving three GMs viz. S. rostrata‐rice/S. rostrata‐rice/S. rostrata registered significantly higher SOC and was 10.63 percent higher than traditional rice–rice cropping system (A₁). This was followed by S. rostrata‐rice/S. rostrata‐rice system. Although the traditional rice–rice cropping system (A₁) also conserved SOC (0.29 and 1.69 % higher than initial during first and second annual cropping cycle, respectively), the magnitude was very low. Repeated application of S. rostrata as GM improved SOC, which formed the basis for sustainable management of soil resources. It can be concluded that S. rostrata would affect the rate of loss of SOC in cropping systems and its ultimate level in soils.     

Yield potential and salt tolerance of quinoa on salt‐degraded soils of Pakistan

Quinoa is recently introduced to Pakistan as a salt‐tolerant crop of high nutritional value. Open field trials were conducted to evaluate its performance on normal and salinity/sodicity‐degraded lands at two locations of different salinity/sodicity levels, S₁ (UAF Farm, Normal Soil), S₂ (Paroka Farm UAF, saline sodic), S₃ (SSRI Farm, normal) and S₄ (SSRI Farm, saline sodic) during 2013–2014. Two genotypes (Q‐2 and Q‐7) were grown in lines and were allowed to grow till maturity under RCBD split‐plot arrangement. Maximum seed yield (3,062 kg/ha) was achieved by Q‐7 at normal field (S₁) soil which was statistically similar with yield of same genotype obtained from salt‐affected field S₂ (2,870 kg/ha). Furthermore, low yield was seen from both genotypes from both S₃ and S₄ as compared to S₁ and S₂. Q‐7 was best under all four conditions. Minimum yield was recorded from Q‐2 (1,587 kg/ha) at S₄. Q‐7 had higher SOD, proline, phenolic and K⁺ contents, and lower Na⁺ content in leaves as compared to Q‐2. High levels of antioxidants and K⁺/Na⁺ of Q‐7 helped to withstand salt stress and might be the cause of higher yields under both normal and salt‐affected soils. Seed quality (mineral and protein) did not decrease considerably under salt‐affected soils even improved seed K⁺, Mg²⁺ and Mn²⁺.     

土壤改良剂对盐化草甸土物理性质及水稻产量的影响

为解决盐化草甸土水稻种植产量低的问题,实现盐碱土可持续利用,本研究采用盆栽试验和大田对比法,通过测定土壤相关物理性状和水稻产量,以期明确土壤改良剂对盐化草甸土的改良效果。盆栽试验结果表明,与常规盆栽管理方式（T1）相比,施用改良剂处理（T2）可显著增加土壤的电导率,降低土壤的代换性钠含量和pH,提高土壤不同粒级水稳性团聚体的质量百分比、有机碳含量和水稻产量;大田对比试验结果表明,与仅灌水处理相比,4个试验地点施用改良剂处理可以显著增加水稻单位面积返青穴数、穗粒数和单位面积产量,增加幅度分别为83.7%~87.4%（P<0.01）、40.4%~98.3%（P<0.01）和293.0%~411.2%（P<0.01）。综上分析,施用土壤改良剂能够明显改善草甸盐土物理性状,提高水稻产量,增加种植户收益。     

Influence of Variable Amounts of Irrigation Water and Nitrogen Fertilizer on Growth, Yield and Water Use of Grain Sorghum

Sorghum hybrid CSH-6 was grown in fields in Delhi, India between July–November 1986 in order to study the effect of nitrogen nutrition and irrigation on dry matter accumulation, grain yield and water use. The treatments included 40 Kg Nha⁻¹ combined with two irrigations (30 DAS, 60 DAS), one irrigation (60 DAS) and no irrigation respectively. Rainfall during the crop season was only 17 cm. The unirrigated plants were considerably water stressed and exhibited very low leaf water potential, less leaf area, delayed anthesis, longer crop duration but shorter grain filling duration. The ears showed sterility and yield was only 0.41 t ha⁻¹ without nitrogen fertilization. Addition of nitrogen fertilizer had no significant effect on yield in unirrigated plants. A single irrigation 60 DAS increased yield due to increase in both grain number and grain weight per ear in fertilized and unfertilized crop respectively. Two irrigations in the unfertilized crop increased the yield to 2.2 t ha⁻¹ while similar treatment in the fertilized crop did not increase the yield significantly. Irrigation increased the WUE for grain yield. The results indicate that nitrogen stress and water stress reduced grain yield primarily through grain number rather than grain weight. Irrigation relieved both water stress and nutrient stress. Nitrogen nutrition was not beneficial under severe water stress conditions but was considerably helpful under mild stress. Biomass, grain yield and harvest index show significant correlation with preanthesis water use.     

不同栽培和灌溉方式对冷浸田障碍因子及水稻产量的影响

为了消减冷浸型中低产田长期浸渍、泥温低、结构差、还原性物质毒害、有效养分低等障碍因子,通过田间小区试验和动态取样与室内测定,研究了不同栽培和灌溉方式对冷浸田障碍因子及水稻产量的影响。结果表明：与常规灌溉方式比较,起垄栽培结合湿润灌溉方式增加了晴朗天气条件下冷浸田土壤温度,土壤气相比例提高3 倍,土壤液相比例减少20%,土壤活性还原物质含量降低了21.9%,土壤细菌数和微生物活性分别提高128.7%和3.8%,土壤排水通气性增强,还原性物质毒害减轻,土壤有效养分提升,为微生物活动创造了优良的条件,最终使早稻增产10.8%。起垄栽培结合湿润灌溉方式是适合于冷浸田早稻增产的农水管理措施。     

Soil sodicity is more detrimental than salinity for quinoa (Chenopodium quinoa Willd.): A multivariate comparison of physiological,biochemical and nutritional quality attributes

Soil salinization is a serious environmental problem worldwide. To explore the comparative effects of soil salinity and sodicity on physiological, biochemical and nutritional quality attributes of four quinoa genotypes (A1, A7, Puno, Vikinga), pot and field experiments were performed on non‐saline soil and two types of salt‐affected soils designated as SS1 (saline) and SS2 (saline‐sodic). The results of both the experiments showed similar reduction pattern in biomass (11%–44%), chlorophyll content (10%–36%), stomatal conductance (18%–32%) and grain yield (30%–47%) of four genotypes on SS2 compared with SS1. Higher sodicity level of SS2 resulted in more Na accumulation (23%–40%) and oxidative damage (12%–35% decrease in membrane stability) leading to an increase in the activities of antioxidant enzymes (SOD, POD, CAT) in all the genotypes. Grain mineral contents (except Na and Mg) were decreased more in SS2 than SS1. Multivariate analysis revealed that grain Na content has negative correlation with all the nutritional quality attributes except Mg and fibre contents. Genotypes A1 and A7 were more salt tolerant with better grain nutritional quality than Puno and Vikinga. It is concluded that soil sodicity is more detrimental than salinity, and quinoa genotypes A1 and A7 are better than Puno and Vikinga for cultivation on saline and saline‐sodic soils.     

不同改良剂与培肥方式对咸灌土壤改良效果的研究

为了探讨改良剂对咸灌土壤的改良效果,采用咸水灌溉下小麦大田种植试验的方法,通过对不同改良剂与培肥方式结合等10个处理的土壤进行采样,分析施用改良剂与培肥方式对咸灌土壤理化性质、养分状况与小麦产量等方面的影响。结果表明,施用改良剂和培肥可降低土壤容重,增大渗透系数和毛管孔隙度,降低土壤pH和全盐含量;增加土壤有机质、速效磷和速效钾含量,而各处理的碱解氮含量低于对照处理;同时可提高小麦产量。因此,在本试验中,T4和T5处理,即改良剂B（醋渣+牛粪+石膏）+有机肥+无机肥和改良剂B+无机肥对改善土壤理化性状、提高土壤养分含量和使小麦增产的效果最好,可作为充分利用咸水资源和盐渍化土壤改良的有效方法。     

Effect of Mulch and Irrigation Water Amounts on Soil Evaporation and Transpiration

Soil evaporation, transpiration, evapotranspiration, and yield of pepper as affected by mulch and five amounts of irrigation water were studied in greenhouse pot experiments during 1996 (March 26–July 13). Five different amounts of irrigation water were imposed on covered and open soil surface clay loam soil in five replicates. Water losses by evaporation and/or transpiration were measured daily by weighing. Irrigation water was applied once weekly. The amount of irrigation water added to each treatment was determined from the differences in weights.
Covering soil surface reduced the required amount of irrigation water. With deficit (under) irrigation, the reduction in applied irrigation water was about 14%. and increased to 29 % with excess (over) irrigation. Transpiration in covered soil surface treatments were higher than transpiration in open soil surface treatments with limited irrigation water applied, With limited (deficit) irrigation, increasing irrigation water applied decreased the percentage of soil evaporation and the contribution of soil evaporation to crop evapotranspiration. With excess irrigation, increasing water applied increased the percentage of soil evaporation and its contribution to the total evapotranspiration. Soil evaporation reduced pepper yield significantly, and this might be owing to the reduction in the available soil water associated with limited-to-complete irrigation.     

不同冬季覆盖作物轮作对农田土壤碳氮影响

风蚀是干旱区农田生态系统中土壤质量降低的关键因素,冬季作物覆盖可有效减少农田的土壤风蚀。通过探究河西灌区不同冬季覆盖作物轮作复种绿肥对农田土壤碳氮影响,以期为构建合理的周年覆盖轮作模式提供理论依据。本研究在热量一熟有余两熟不足的河西灌区春小麦种植区把冬小麦、冬油菜两种冬季覆盖作物和绿肥还田处理嵌套种植形成：（1）春小麦—冬油菜—箭筈豌豆(WCP)、（2）春小麦—冬小麦—箭筈豌豆(WWP)、（3）春小麦—箭筈豌豆(WP)、(4)春小麦—春小麦(W,CK)不同种植模式,在360 kg/hm² (N2)、270 kg/hm² (N1)、0 kg/hm² (N0) 3个施氮水平下,研究不同轮作模式对农田土壤碳、氮含量的提升效应。结果表明：在同一种植模式下土壤有机碳、土壤可溶性有机碳、热提取态有机碳、硝态氮、氨态氮、微生物量碳氮含量随施氮量的增加而增加,但在氮肥减量(N1)的条件下,与常规施氮(N2)相比较WCP轮作模式土壤有机碳、土壤可溶性有机碳、热提取态有机碳含量及微生物量氮无显著降低。相同施氮条件下,轮作模式间差异不显著,但与CK间差异显著;其中,0~10 cm土层,WCP轮作模式土壤有机碳、土壤可溶性有机碳、土壤热提取态有机碳、硝态氮、氨态氮、微生物量碳氮含量平均较CK提高5.42%、9.78%、10.96%、20.51%、15.76%、18.94%;10~30 cm土层,提高9.54%、7.06%、12.99%、20.12%、16.51%、18.16%。因此,春小麦轮作冬油菜复种绿肥模式在氮肥减量条件下仍对农田土壤碳氮有明显的提升效应,为河西灌区良好的周年覆盖作物轮作模式。     

Preliminary Research on Seed Production and Nutrient Content for Certain Quinoa Varieties in a Saline–Sodic Soil

The aim of the present study was to compare the potential seed yield of eight quinoa varieties, to explore their mineral composition of seeds and to identify superior varieties in two locations with different soil properties. Compared with neutral soil conditions, seed yield in the marginal (saline–sodic) soil was decreased by 45 %. Under the latter soil conditions seed yield was negatively correlated with crop density, indicating that a considerable yield loss was due to poor and uneven plant density caused by adverse soil properties. Among the varieties, ‘RU–5–PQCIP–DANIDA–UNA’ produced the highest seed yield (>20 dt ha^?1) when grown under neutral soil conditions. Under marginal conditions, the above‐mentioned variety and ‘N 407’ produced seed yields up to 10 dt ha^?1 whereas the rest reached yields of only about 5 dt ha^?1. The majority of the varieties accumulated significantly more protein (20 %) in the seeds under saline–sodic soil conditions (lower yielding environment). The varieties originated from South America were superior in accumulating protein in the seeds at both locations. Mineral contents of calcium (Ca), magnesium (Mg), zinc (Zn) and manganese (Mn) in the seeds were significantly higher in the neutral soil. No differences were found for phosphorous (P), iron (Fe), copper (Cu) and boron (B) between the two locations. The South American varieties were again superior in mineral composition. Adaptation of certain quinoa varieties even under marginal environments seems promising for seed production and/or protein and mineral content in the seeds. Agronomic data are needed in a due course, over a higher number of locations and/or various climatic conditions.     

不同底墒条件下补灌对冬小麦耗水特性、产量和水分利用效率的影响

我国黄淮平原水资源紧缺,而且年际间降水量及其时间分布存在较大差异,探明不同底墒条件下补充灌溉对冬小麦产量和水分利用效率的调节效应及其生理基础,可为该地区冬小麦节水高产栽培提供理论和技术支持。2013—2014和2014—2015年冬小麦生长季,在播种期0~100 cm土层土壤贮水量分别为201.5(A)、266.3(B)和317.0mm(C)3种底墒条件下,各设置4个补灌水处理,包括不灌水、拔节期+开花期补灌、越冬期+拔节期+开花期补灌、播种期+拔节期+开花期补灌,研究不同处理冬小麦耗水特性、旗叶光合、干物质积累与分配、产量及水分利用效率的差异。结果表明,冬小麦生育期总耗水量和土壤水消耗量均随播种期底墒的提高而增加。在底墒A和B条件下,冬小麦主要消耗降水和灌溉水。提高播种期补灌水平或于越冬期补灌,冬小麦在底墒A条件下对土壤水的消耗量显著增加,在底墒B条件下对土壤水的消耗量显著减少。在底墒C条件下,冬小麦耗水以土壤水为主,其次为降水,再次为灌溉水;播种期或越冬期补灌显著增加生育期总耗水量,对土壤水消耗量则无显著影响。于播种期、拔节期和开花期补灌,冬小麦在底墒A条件下可获得较高的籽粒产量,但水分利用效率较低;在底墒B条件下籽粒产量和水分利用效率均较高;在底墒C条件下,仅于拔节期和开花期补灌即可获得高产和高水分利用效率,播种期和越冬期无需补灌。综上所述,播前底墒是实施冬小麦合理补灌的重要依据。     

Irrigation and Nutrient Effects on Growth and Water–Yield Relationship of Wheat (Triticum aestivum L.) in Central India

Increasing production of wheat from a limited water supply can result from efficient irrigation and nutrient management. A 3‐year field experiment was conducted at the Indian Institute of Soil Science, Bhopal, to study the growth, yield, seasonal evapotranspiration (ET) and water use efficiency (WUE), and the water–yield relationship of wheat in a soybean–wheat cropping system on vertisols. Three levels of irrigation, viz. I₀, no post‐sowing irrigation; I₁, two irrigations [crown root initiation (CRI) and flowering stage]; and I₂, three irrigations (CRI, maximum tillering and flowering stage) and three nutrient management treatments, viz. F₀, control (without fertilizer/manure); F₁, 100 % NPK (100–21.5–24.9 kg ha^?1); and F₂, 100 % NPK + farmyard manure (FYM‐10 t ha^?1) were tested in a split‐plot design with three replication. It has been established (through anova ) that the year effect was rather negligible and the interaction effects of irrigation and nutrient management on the growth parameters, ET, yield components, yield and WUE were significant. Plant height, progressive leaf area index, dry matter accumulation and crop growth rate were higher in I₂F₂, and I₂F₁ and I₁F₂ were statistically at par. The seasonal ET increased significantly with the increase in water supply in every nutrient treatment and it was highest in I₂F₂ and lowest in I₀F₀. The highest grain yield was obtained in I₂F₂; and a similar yield was recorded in I₃F₁ and I₂F₂. This shows a strong interaction effect between irrigation and nutrients. Yield components, viz. number of ears m^?2, number of grains ear^?1 and 1000‐grain weight were significant. The higher number of ears m^?2 containing greater number of grains with relatively heavier weights appeared to have contributed to the higher yield in I₁F₂, I₂F₁ and I₂F₂. The highest WUE obtained in I₀F₂ did not correspond to the highest yield and maximum ET, but a WUE of 10.43 kg ha^?1 mm^?1 in the I₂F₂ combination corresponded with the highest yield and the seasonal ET requirement was 391.8, which was 137 % greater than the water use at maximum WUE. The ET–grain yield relationship was linear, with a lowest regression slope (i.e. marginal WUE) and elasticity of water production (E_wp) in F₀ and a considerably higher slope and E_wp in F₁ and F₂. As the E_wp is positive and close to one in 100 % NPK treatment, the scope of improving WUE and yield with only inorganic fertilizer is very little, and relatively greater scope exists in the integrated management of organic manure and inorganic fertilizer. The results suggest that integrated nutrient management (100 % NPK + FYM) in conjunction with three irrigations maximized yield of wheat with concomitant improvement in ET and WUE under limited water availability.     

灌溉制度对机采棉生长、产量及品质的影 响简

 1膜2管6行是新疆机采棉的主要种植模式。为确定该模式适宜的灌溉制度,采用田间试验研究了灌溉频率（F5、F8）与灌水定额（I80、I60和I40）对棉花生长、产量、品质及水分利用效率的影响。结果表明,高频高定额（F5I80）与高频中定额（F5I60）灌溉可有效降低棉花株高,增加叶面积指数,提高蕾铃生物量在地上部中的比例。灌溉频率相同时,灌水量过高与过低均不利于棉花增产;灌水定额相同时,高频（F5）较低频（F8）灌溉增产0.59%~1.56%。灌溉制度对棉花纤维品质无显著影响。灌水定额显著影响棉花耗水量及水分利用效率,而灌溉频率对二者影响不显著。研究认为高频（F5）和中灌溉定额（I60）是南疆地区机采棉种植模式适宜的灌溉制度,即在全生育期内灌水12次,灌溉定额300 mm左右。