Evaluation on the irrigation and fertilization management practices under the application of treated sewage water in Beijing, China

Irrigation and fertilization management practices play important roles in crop production. In this paper, the Root Zone Water Quality Model (RZWQM) was used to evaluate the irrigation and fertilization management practices for a winter wheat–summer corn double cropping system in Beijing, China under the irrigation with treated sewage water (TSW). A carefully designed experiment was carried out at an experimental station in Beijing area from 2001 to 2003 with four irrigation treatments. The hydrologic, nitrogen and crop growth components of RZWQM were calibrated by using the dataset of one treatment. The datasets of other three treatments were used to validate the model performance. Most predicted soil water contents were within ±1 standard deviation (S.D.) of the measured data. The relative errors (RE) of grain yield predictions were within the range of −26.8% to 18.5%, whereas the REs of biomass predictions were between −38% and 14%. The grain nitrogen (N) uptake and biomass N uptake were predicted with the RE values ranging from −13.9% to 14.7%, and from −11.1% to 29.8%, respectively. These results showed that the model was able to simulate the double cropping system variables under different irrigation and fertilization conditions with reasonable accuracy. Application of RZWQM in the growing season of 2001–2002 indicated that the best irrigation management practice was no irrigation for summer corn, three 83 mm irrigations each for pre-sowing, jointing and heading stages of winter wheat, respectively. And the best nitrogen application management practice was 120 kg N ha⁻¹ for summer corn and 110 kg N ha⁻¹ for winter wheat, respectively, under the irrigation with TSW. We also obtained the alternative irrigation management practices for the hydrologic years of 75%, 50% and 25%, respectively, in Beijing area under the conditions of irrigation with TSW and the optimal nitrogen application.     

Assessing benefits of irrigation and nutrient management practices on a southeast Florida royal palm (Roystonea elata) field nursery

Many of the best management practices (BMPs) that are recommended for agricultural producers have not been scientifically evaluated for their conservation benefits considering the soil, climate, and hydrology of the proposed application location. The goal of this study was to compare royal palm (Roystonea elata) production in south Florida, USA, using tensiometer automated irrigation and reduced soil applications of nitrogen (N) and phosphorus (P), to that of traditional grower practices considering water savings, nutrient inputs, crop yield, crop nutrient status, soil nutrient status, and economic analyses. The study consisted of six treatments: (1) control (i.e., a grower irrigation rate and N and P fertilizer rates); (2) irrigation system automated to irrigate when soil water suction exceeded 5 kPa and the grower N and P rates; (3) irrigation system automated to irrigate when soil water suction exceeded 15 kPa and the grower N and P rates; (4) irrigation system automated to irrigate when soil water suction exceeded 15 kPa and 50% of the grower N and P rates; (5) the grower irrigation rate and 75% of the grower N and P rates; and (6) the grower irrigation rate and 50% of the grower N and P rates. Irrigation water volume applied, plant diameters, and plant heights were measured periodically throughout the study and plant tissue samples and soil samples were collected periodically for analysis of N and P content. Significant differences among treatments were only observed for the irrigation water volume applied. Automating the irrigation system to irrigate at soil suction exceeding 5 and 15 kPa resulted in 75 and 96% less water applied, respectively, than traditional irrigation scheduling practices used by a grower. Economic analyses suggested that all treatments would result in financial savings ranging from 7 to 34% per ha considering a 5-year, 2 ha investment. Thus, automating irrigation based on soil water suction for palm production in southern Florida, USA and similar locations will result in more sustainable agricultural production systems by benefiting the environment (less nutrients and water applied) and the grower (lower cost).     

Synthetic and organic mulching and nitrogen effect on winter wheat (Triticum aestivum L.) in a semi-arid environment

Field experiments were conducted in 2002-2003 and 2003-2004 to evaluate the relative performance of synthetic (black polyethylene) and organic (paddy husk and straw) mulches on soil and plant water status vis-a-vis N uptake in wheat in a semi-arid environment of India. Scope of better utilization of soil moisture was documented through all the mulches, especially during initial crop growth stages, when the moisture content was 1-3% higher in mulches. Soil temperature was more moderate under organic mulches. Paddy husk recorded significantly higher plant biomass, while the effect of mulching in enhancing root growth was clearly documented. Organic mulches produced more roots (25 and 40% higher root weight and root length densities compared to no-mulch) in sub-surface (>0.15 m) layers, probably due to greater retention of soil moisture in deeper layers and relatively narrow range of soil temperature changes under these systems. Incremental N dose significantly improved all the plant parameters in both mulch and no-mulch treatments. Grain yield was 13-21% higher under mulch and so with increasing N levels. Nitrogen uptake was higher in organic mulches and also with higher N doses, while polyethylene mulch showed mixed trend. Mulches were effective in reducing 3-11% crop water use and improved its efficiency by 25%. Grain yield and biomass were well-correlated with leaf area index (r = 0.87 and 0.91, respectively) and water use was better correlated with root length than its weight. Results indicated substantial improvement in water and N use efficiency and crop growth in wheat under surface mulching, and the organic mulches, especially rice husk performed better than synthetic mulches.     

Crop yield and soil water restoration on 9-year-old alfalfa pasture in the semiarid Loess Plateau of China

The alfalfa pastureland in the semiarid Loess Plateau region of Northwest China usually has dry soil layers. A field experiment was conducted from October 2000 to October 2004 to examine soil water recovery and crop productivity on a 9-year-old alfalfa pasture. This experiment included six treatments: alfalfa pasture for 10-14 years, a conventional farming system without prior alfalfa planting, and four alfalfa-crop rotation treatments. For the rotation treatments, after 9 years of alfalfa selected crops were planted from 2001 to 2004 in the following sequence: (1) millet, spring wheat, potatoes, peas; (2) millet, corn, corn, spring wheat; (3) millet, potatoes, spring wheat, corn; (4) millet, fallow, peas, potatoes. The results showed that dry soil layers occurred in alfalfa pasture. We then plowed the alfalfa pasture and planted different crops. The soil water gradually increased during crop growth in the experimental period. The degree of soil water recovery in the four alfalfa-crop rotation treatments was derived from comparison with the soil water in the conventional system. After 4 years, the soil water recovery from the alfalfa-crop rotation systems at 0-500 cm soil depth was 90.5%, 89.8%, 92.2% and 96.7%, respectively. Soil total N content and soil respiration rate were high in the alfalfa-crop rotation systems. The yields of spring wheat in 2002, peas in 2003 and potatoes in 2004 in the alfalfa-crop rotation systems were not significantly different from yields in the conventional system. In the alfalfa-crop rotation systems, the yields of spring wheat and peas were greatly influenced by rainfall and were lowest in the dry year of 2004; the yields of corn and potatoes had a direct relationship with water use and were lowest in 2003. In summary, soil water in dry soil layers can recover, and crop yields in the alfalfa-crop systems were equal to those of the conventional system.     

拔节期淹水条件下施氮量对玉米干物质积累和氮素吸收利用的影响

[目的]揭示拔节期淹水胁迫下施氮量对玉米干物质积累分配及氮素吸收利用的影响.[方法]以春玉米"宜单629"为供试作物,采用2因素裂区田间试验,主处理为土壤水分状况,包括全生育期适宜水分(CS处理)和拔节期淹水6d(YS处理);副处理为施氮量,包括0、90、180、270 kg/hm2和360 kg/hm2,分别记为N0...     

不同生育阶段土壤水分和养分空间变异与冬小麦产量关系的研究

以江苏省姜堰市沈高农场为例,分析了冬小麦生育期内土壤水分和养分产量的空间变异性,主成分-逐步回归的适当组合,能较为满意地降低土壤特性与产量关系分析中多重共线性的干扰,分析结果表明,土壤水分属弱变异性,养分属程度不同的中等变异性;所测土壤特性与产量关系的亲疏大致为:有机质和全氮量最密切,其次是速效氮,再次是速效钾,接下来是土壤水分和速效磷。     

秸秆覆盖对冬小麦的影响

研究了"黄淮海"一年两熟地区秸秆覆盖对冬小麦的生长发育和产量性状及其构成要素的影响.试验表明:秸秆覆盖可以改善土壤的理化性状,增加土壤养分有效性,可提高水分利用率,提高土壤的生物活性,明显地调节作物生长的水、肥、气、热等生态条件,促进了小麦的生长发育,可以明显提高小麦的产量.未进行秸秆覆盖的处理产量为4 617.93kg/hm2;进行秸秆覆盖的处理,小麦平均产量最高可达到 5 360.00kg/hm2,提高了1 303.67kg/hm2,增产可达到 28.23%.     

Water and nitrogen interaction on soil profile water extraction and ET in maize-wheat cropping system

In the present study, water and nitrogen interaction on soil profile water extraction and evapo-transpiration (ET) was investigated taking a field experiment on a clay loam soil (Typic Haplustept) at the Indian Agricultural Research Institute, New Delhi with four consecutive crops (maize-wheat-maize-wheat) taken from July 2002 to April 2004. Three levels of water regime, namely W1, W2 and W3 referring to limited, medium and maximum irrigation were applied to each crop depending on the seasonal rainfall and the critical crop growth stage. The three water regimes were used with five nitrogen levels from T1 to T5, (T1, 0% N; T2, 75% N; T3, 100% N; T4, 150% N; T5, 100% N from organic source) in a split plot design for the four crops grown in sequence.Significant water and nitrogen interaction was observed for ET and soil profile water extraction pattern. Averaged across nitrogen treatments, ET in W2 and W3 were higher by 17 and 26%, respectively than W1 in maize 2002 and by 12 and 19% in maize 2003. In case of wheat, ET in W2 and W3 were higher by 27 and 58% than W1 in 1st crop and by 37 and 70% in 2nd crop. The effect of nitrogen regime, however, was prominent in both crops of maize and wheat, with significantly higher profile soil moisture depletion in T4 of each water regime. In all cases, lowest water depletion was observed in control plots receiving 0% N.In both crops, water extraction from surface 60 cm was highest in W3 followed by W2 and W1. In maize, the % extraction from 0 to 60 cm layer varied from 71 to 76% (W1), 70-79% (W2) and 75-82% (W3), whereas the values for wheat were 70-77, 72-79 and 75-83% for W1, W2 and W3, respectively. The 90-120 cm layer contributed only 3-14% to total water extraction in both the crops. From 90 to 120 cm layer, higher extraction was observed in W1 as compared to W3. The extraction values in W1, W2 and W3 in maize were 9-13, 7-14 and 3-9, respectively, whereas the corresponding values in wheat were 8-14, 5-12 and 3-7% for the three water regimes. Effect of nitrogen treatments on water extraction from deeper layer was observed with higher extraction in highest fertilized treatment (T4) as compared to other treatments.     

Effect of treated effluent irrigation and nitrogen on yield and nitrogen use efficiency of wheat

Yield and nitrogen use efficiency (NUE) of wheat was investigated under field conditions using two types of irrigation waters with and without nitrogen on a sandy-loam to loamy-sand soil during 1992–1993 and 1993–1994. Depending upon different nitrogen treatments, the mean crop yield ranges in 1992–1993 were: grain yield 6.19–6.87 Mg ha⁻ and biomass 15.41–16.34 Mg ha⁻¹ receiving treated effluent. The mean crop yield ranges in 1993–1994 were: grain yield 0.46–3.23 Mg ha⁻¹ (well water) and 5.20–6.54 Mg ha⁻¹ (treated effluent); and biomass 1.84–10.80 Mg ha⁻¹ (well water), and 16.00–19.29 Mg ha⁻¹ (treated effluent). The NUE for grain yield in 1992–1993 was between 16.70–50.23 kg kg⁻¹ N (well water) and 20.65–91.56 kg kg⁻¹ N (treated effluent). Whereas the NUE in 1993-94, varied between 10.49–32.13 kg grain kg⁻¹ N (well water) and 21.30–72.93 kg grain kg⁻¹ N (treated effluent). The NUE for total biomass in 1992–1993 varied between 46.54–130.32 kg kg⁻¹ N (well water) and 53.66–158.77 kg kg⁻¹ N (treated effluent). Similarly, the NUE in 1993–1994 varied between 35.99–102.1 kg biomass kg⁻¹ N (well water) and 59.27–161.89 kg biomass kg⁻¹ N (treated effluent). A significant decrease in NUE was observed with increasing nitrogen application both for grain and biomass production. In conclusion, a higher grain yield and NUE of wheat crop can be achieved with low application rates of nitrogen if the crop is irrigated with treated effluent containing nitrogen in the range of 20 mg L⁻¹ and above.     

Effect of mulching on soil and plant water status, and the growth and yield of wheat (Triticum aestivum L.) in a semi-arid environment

Mulching is one of the important agronomic practices in conserving the soil moisture and modifying the soil physical environment. Wheat, the second most important cereal crop in India, is sensitive to soil moisture stress. Field experiments were conducted during winter seasons of 2004-2005 and 2005-2006 in a sandy loam soil to evaluate the soil and plant water status in wheat under synthetic (transparent and black polyethylene) and organic (rice husk) mulches with limited irrigation and compared with adequate irrigation with no mulch (conventional practices by the farmers). Though all the mulch treatments improved the soil moisture status, rice husk was found to be superior in maintaining optimum soil moisture condition for crop use. The residual soil moisture was also minimum, indicating effective utilization of moisture by the crop under RH. The plant water status, as evaluated by relative water content and leaf water potential were favourable under RH. Specific leaf weight, root length density and dry biomass were also greater in this treatment. Optimum soil and canopy thermal environment of wheat with limited fluctuations were observed under RH, even during dry periods. This produced comparable yield with less water use, enhancing the water use efficiency. Therefore, it may be concluded that under limited irrigation condition, RH mulching will be beneficial for wheat as it is able to maintain better soil and plant water status, leading to higher grain yield and enhanced water use efficiency.     

Effect of frequency of sodic and saline-sodic irrigations and gypsum on the buildup of sodium in soil and crop yields

The effect of three frequencies of irrigation with sodic (high residual alkalinity) and saline-sodic (high residual alkalinity and high NaCl concentration) waters in presence and absence of gypsum application on soil properties and crop yields were investigated under millet (fodder) — wheat — maize (fodder) rotation in a field experiment carried out for 6 years (1986–1992) on a well drained sandy loam Typic Ustochrept soil. Irrespective of the irrigation intervals, sustained use of sodic and salinesodic waters increased pH, electrical conductivity and ESP of the soil and hence significantly decreased crop yields. Application of gypsum decreased ESP and significantly improved crop yields. The beneficial effect of gypsum was lower under saline-sodic irrigation. There were no significant beneficial effects of increasing the frequency of sodic and saline-sodic irrigation, both in presence and absence of applied gypsum, on the yields of wheat and millet (f) crops grown during winter and monsoon seasons, respectively. But decrease in irrigation interval significantly improved yields of maize (f) grown during the hot dry summer period. Frequency of irrigation did not appreciably alter the effectiveness of applied gypsum in wheat and millet (f) but in maize (f), the gypsum treatment was more effective under more frequent irrigation.     

Identification and discrimination of water stress in wheat leaves (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) by means of reflectance measurements

Available water is one of the most limiting factors in crop production. As current methods for the determination of plant water content are time-consuming and require numerous observations to characterize a field, managers could benefit from remote sensing techniques to assist in irrigation decisions and further management practices. Adoption will depend on the development of technologies, which allow real time sensing of the soil and plant water status and the discrimination of several stress factors. A greenhouse study was initiated to determine specific wavelengths and/or combinations of wavelengths indicative of water stress in wheat and to evaluate these wavelengths for discriminating water stress from other biotic stresses. Reflectance of wheat leaves from plants grown under six different water treatments ranging from 65 to 26% field capacity was determined once a week from the beginning of the fourth leaf stage until the sixth leaf stage. Reflectance measurements were performed at the fourth leaf of wheat plants with an imager (LEICA S1 Pro) under controlled light conditions. Reflectance was measured in different wavelength ranges throughout the visible and infrared spectra (380–1,300 nm). Leaf scans were evaluated within the L*a*b*-color system. Total water content of wheat leaves was calculated after the difference between total fresh and total dry weight of wheat plants. Significant reflectance changes and correlations between water status and leaf reflectance were obtained at a water content <71% and enabled the identification and quantification of water status of wheat plants. Reflectance patterns at 510₇₈₀, 540₇₈₀, 490_1,300, and 540_1,300 nm were found most suitable to describe to the water status regardless of the sampling date or growth stage. To evaluate the validity of leaf reflectance as a method for separating water stress from other biotic stresses such as nutrient deficiencies reflectance pattern of water deficient plants were compared with reflectance patterns of N, P, Mg, and Fe deficiency obtained in earlier studies by calculating the color distance ΔEab as additional reflectance parameter. ΔEab increased under different nutrient deficiencies, but remained constant under water stress, thus enabling the discrimination of the investigated stress factors. The approach indicated that various stress factors could be clearly identified by reflectance measurements, thus enhancing a better plant management by the use of remote sensing techniques.     

Optimizing the yield of winter wheat by regulating water consumption during vegetative and reproductive stages under limited water supply

To ensure sustainable agricultural water use in water shortage regions, practices of deficit irrigation should be adopted. This study investigated the performance of winter wheat (Triticum aestivum L.) under limited water supply from 2005 to 2011, a six-season field test on the North China Plain. The test was comprised of four treatments: rain-fed, single irrigation applied at sowing to obtain a good level of soil moisture at the start of crop growth (I1s), single irrigation applied during recovery to jointing (I1r), and full irrigation supplied as three irrigations (control, I3). The results showed that grain yield was significantly correlated with rainfall before heading and with evapotranspiration (ET) after heading (P < 0.01) under rain-fed conditions. The average contribution of soil water stored before sowing to seasonal ET was 90, 103, and 145 mm for rain-fed, I1s, and I1r, respectively, during the six seasons. A smaller root length density (RLD), which restricted utilization of deep soil water by the crop, was one of the reasons for the lower yield with rain-fed and I1s treatments compared with the I1r treatment in dry seasons. The results also showed that the limited irrigation applied from recovery to jointing stage (Treatment I1r) significantly promoted vegetative growth and more efficient soil water use during the reproductive (post-heading) stage, resulting in a 21.6 % yield increase compared with that of the I1s treatment. And although the average yield of the I1r treatment was 14 % lower than that of the full irrigation treatment, seasonal irrigation was reduced by 120–140 mm. With smaller penalties in yield and a larger reduction in applied irrigation, I1r could be considered a feasible irrigation practice that could be used in the NCP for conservation of groundwater resources.     

Tillage and irrigation effects on crop yields and soil properties under the rice-wheat system in the Indian Himalayas

Conservation tillage systems generally improve soil organic C (SOC), plant available water capacity (PAWC), aggregation and soil water transmission. A field experiment was conducted for 4 years (2001-2002 to 2004-2005) to study tillage (conventional tillage (CT) and zero tillage (ZT)) systems. The selected irrigation treatments were at four levels (I₁: pre-sowing (PS), I₂: PS + active tillering (AT)/crown root initiation (CRI), I₃: PS + AT/CRI + panicle initiation (PI)/flowering (FL), and I₄: PS + AT/CRI + PI/FL + grain filling (GF)), applied at the critical growth stages on rice (Oryza sativa L.) and wheat (Triticum aestivum L.). Their effects on direct seeded rice productivity and soil properties (SOC and selected physical properties) after rice and wheat harvest were investigated. Soil organic C contents after rice and wheat harvest in the 0-15 cm soil depth were higher under ZT than under CT. Soil organic C increased significantly with I₂ over I₁ for both crops and with I₄ over I₂ for the wheat crop. The PAWC was significantly higher with ZT than CT. Zero tilled and frequently irrigated plots showed enhanced infiltration characteristics (infiltration rate, cumulative infiltration and sorptivity) and saturated hydraulic conductivity. Both direct seeded rice and wheat yields were not significantly different in the plots under ZT and CT. There was a significant increase in both rice and wheat yields in the plots under I₂ over I₁. However, water use efficiency between irrigation treatments was not significantly different. Hence, under direct seeded rice-wheat system in a sandy clay loam soil of the sub-temperate Indian Himalayas, farmers may adopt ZT with two irrigations in each crop for optimum resource conservation.     

不同年代冬小麦品种水分利用效率差异分析

通过田间试验对黄淮地区不同年代代表性冬小麦品种的需水特性、产量组成及水分利用效率进行了研究。结果表明,虽然不同年代冬小麦品种的耗水量存在一定的波动,但基本上保持稳定。在低水、中水和高水条件下,各品种耗水量的平均值分别为289.40、357.64、402.70mm。与20世纪50—60年代的品种相比,现代冬小麦品种的籽粒产量能提高53%(低水)、78%(中水)和46.6%(高水),水分利用效率(WUE)则分别提高了45.6%(低水)、63.4%(中水)和57.8%(高水)。在耗水量基本保持稳定的实际情况下,产量水平提高是不同年代冬小麦品种WUE提高的主导因素。     

Studies on the nitrogen and water relations of wheat

Summary The interrelations between nitrogen and water supply on the growth and yield of wheat (Triticum aestivum L.) were studied with particular attention to water use and grain yield in relation to the time of application of nitrogen to the plants. Nitrogen was applied at seeding or deferred until the double ridge-stage of development. Effects of both soil-applied and foliar-applied nitrogen were investigated under deficient or adequate water supply. The supply of water to the crop controlled the level of yield obtained and the response of the crop to applied N was markedly greater in drought-free conditions. Application of N resulted in increases in both crop leaf area duration and water use. Greater responses to N were obtained when the fertilizer was applied to the soil, rather than as a foliar spray.     

花前干旱胁迫对冬小麦生长指标的影响

【目的】研究干旱胁迫对冬小麦生长指标的影响。【方法】选用周麦22为试验材料,在拔节期和抽穗期分别设置轻度干旱(土壤含水率控制在田间持水率的60%~70%)、中度干旱(土壤含水率控制在田间持水率的50%~60%)和重度干旱(土壤含水率控制在田间持水率的40%~50%),对比分析了冬小麦根系形态、根系分布、株高及叶面积的变化过程。【结果】干旱胁迫处理根长相比CK均降低,T1、T2、T3处理总根长随干旱程度的加深而增长;经过连续处理的各根系特征在轻旱、中旱条件下均大于单阶段处理,重旱条件下各根系特征则明显降低;但复水后拔节期处理的根系补偿恢复能力高于抽穗期。随着干旱胁迫程度及时间增加,根系向下伸展生长,使各根系指标向深层转移,但根系总体绝对量明显减少,T9处理根干质量相比CK降低64.79%,并且株高、叶面积所受的抑制增大。其中拔节期对株高影响更大,T1、T2、T3处理株高相比CK降低3.78%、7.59%、16.09%;抽穗期对叶面积影响更大,T4、T5、T6处理叶面积相比CK降低8.11%、23.45%、29.43%;而经连续干旱处理后的株高和叶面积都明显低于各单阶段处理;抽穗期经干旱胁迫处理的株高、叶面积在干旱胁迫1周后就表现出较强补偿效应,而拔节期表现则相对迟缓;在经历连续干旱胁迫后均无明显补偿。【结论】在冬小麦实际生产中应避免连续干旱,花前若需控水,应尽量满足拔节期供水,控水在抽穗期保持轻旱水平。     

Measurements and simulations of heat and water balance components in a clay soil cropped with winter wheat under drought stress or daily irrigation and fertilization

Soil water and temperature dynamics were measured in a field experiment with winter wheat on a clay soil. There were four treatments: Control (C), receiving natural precipitation, drought (D), protected from rain by plastic screens during the growing season, daily irrigation (I) and daily irrigation and fertilization (IF). Treatments C, D and I received the nitrogen fertilizer as a single application of solid fertilizer in spring. In IF daily dressings of nutrients were supplied in the irrigation water. All treatments received 20 g Nm^–2. An associated experiment with a newly sown grass ley (L) that was irrigated and fertilized daily (total 5.6 g Nm ^–2) was also performed. Standard meteorological variables (air temperature and humidity, wind speed, precipitation, global radiation, and relative cloudiness) and crop development data (green area index, crop height, relative root distribution in depth) above and below ground were used as driving variables within a physically based dynamic model (SOIL) for simulating water and heat fluxes. Measured soil temperature and water content from one treatment (I) were used to tune the model parameters, tentatively set from literature data. Thereafter, water and heat fluxes in the other treatments were simulated using the same parameter values but with different crop-related measurements as driving variables for each treatment. Measured soil temperature and water content in C, D, IF and L could thus be used for validation of the simulations. The theory formulated in the model could accurately explain measured treatment differences in soil water and temperature dynamics. Since the soil-related parameters were identical in all treatments, the model was shown to be applicable over a wide range of moisture conditions.     

干旱环境下春小麦最优调亏灌溉制度确定

以河西绿洲灌区春小麦调亏灌溉2年的平均产量、水分利用效率、供水效率和2年后的土壤养分综合指标4个单项参评因子为参数建立单因子评判矩阵,对干旱环境下春小麦调亏灌溉制度进行了综合评价。结果表明,调亏灌溉处理的综合评价指标以HFF处理最高,其次为MFM处理,而以LLL处理最低,但所有调亏灌溉处理综合评价指标均显著高于高水分处理FFF。因此,无论是从作物生产力、水资源利用效率还是水资源和土壤养分的可持续利用方面来说,HFF处理调亏灌溉模式均因其最高的作物生产力和水分利用效率、较高的供水效率(为最大值的96.3%)及较高的土壤养分综合指标(为最大值的97.7%)而具有最高的综合评价指标,成为试区推荐的春小麦全生育期最优调亏灌溉模式,即春小麦孕穗和抽穗期及灌浆—生理成熟期均高水分处理(65%~70%田持)而拔节期重度水分调亏(45%~50%田持),其灌溉定额为440 mm左右(包括晚秋季储水灌100 mm)。     

Integrated management of irrigation water and fertilizers for wheat crop using field experiments and simulation modeling

The reported study aimed at developing an integrated management strategy for irrigation water and fertilizers in case of wheat crop in a sub-tropical sub-humid region. Field experiments were conducted on wheat crop (cultivar Sonalika) during the years 2002–2003, 2003–2004 and 2004–2005. Each experiment included four fertilizer treatments and three irrigation treatments during the wheat growth period. During the experiment, the irrigation treatments considered were I₁ = 10% maximum allowable depletion (MAD) of available soil water (ASW); I₂ = 40% MAD of ASW; I₃ = 60% MAD of ASW. The fertilizer treatments considered in the experiments were F₁ = control treatment with N:P₂O₅:K₂O as 0:0:0 kg ha⁻¹, F₂ = fertilizer application of N:P₂O₅:K₂O as 80:40:40 kg ha⁻¹; F₃ = fertilizer application of N:P₂O₅:K₂O as 120:60:60 kg ha⁻¹ and F₄ = fertilizer application of N:P₂O₅:K₂O as 160:80:80 kg ha⁻¹. In this study CERES-wheat crop growth model of the DSSAT v4.0 was used to simulate the growth, development and yield of wheat crop using soil, daily weather and management inputs, to aid farmers and decision makers in developing strategies for effective management of inputs. The results of the investigation revealed that magnitudes of grain yield, straw yield and maximum LAI of wheat crop were higher in low volume high frequency irrigation (I₁) than the high volume low frequency irrigation (I₃). The grain yield, straw yield and maximum LAI increased with increase in fertilization rate for the wheat crop. The results also revealed that increase in level of fertilization increased water use efficiency (WUE) considerably. However, WUE of the I₂ irrigation schedule was comparatively higher than the I₁ and I₃ irrigation schedules due to higher grain yield per unit use of water. Therefore, irrigation schedule with 40% maximum allowable depletion of available soil water (I₂) could safely be maintained during the non-critical stages to save water without sacrificing the crop yield. Increase in level of fertilization increases the WUE but it will cause environmental problem beyond certain limit. The calibrated CERES-wheat model could predict the grain yield, straw yield and maximum LAI of wheat crop with considerable accuracy and therefore can be recommended for decision-making in similar regions.