Effect of water management on dry seeded and puddled transplanted rice: Part 2: Water balance and water productivity

Labour and water scarcity in north west India are driving researchers and farmers to find alternative management strategies that will increase water productivity and reduce labour requirement while maintaining or increasing land productivity. A field experiment was done in Punjab, India, in 2008 and 2009 to compare water balance components and water productivity of dry seeded rice (DSR) and puddled transplanted rice (PTR). There were four irrigation schedules based on soil water tension (SWT) ranging from saturation (daily irrigation) to alternate wetting drying (AWD) with irrigation thresholds of 20, 40 and 70 kPa at 18–20 cm soil depth. There were large and significant declines in irrigation water input with AWD compared to daily irrigation in both establishment methods. The irrigation water savings were mainly due to reduced deep drainage, seepage and runoff, and to reduced ET in DSR. Within each irrigation treatment, deep drainage was much higher in DSR than in PTR, and more so in the second year (i.e. after 2 years without puddling). The irrigation input to daily irrigated DSR was similar to or higher than to daily irrigated PTR. However, within each AWD treatment, the irrigation input to DSR was less than to PTR, due to reduced seepage and runoff, mainly because all PTR treatments were continuously flooded for 2 weeks after transplanting. There was 30–50% irrigation water saving in DSR-20 kPa compared with PTR-20 kPa due to reduced seepage and runoff, which more than compensated for the increased deep drainage in DSR. Yields of PTR and DSR with daily irrigation and a 20 kPa irrigation threshold were similar each year. Thus irrigation and input water productivities (WP_I and WP_I+R) were highest with the 20 kPa irrigation threshold, and WP_I of DSR-20 kPa was 30–50% higher than of PTR-20 kPa. There was a consistent trend for declining ET with decreasing frequency of irrigation, but there was no effect of establishment method on ET apart from higher ET in DSR than PTR with daily irrigation. Water productivity with respect to ET (WP_ET) was highest with a 20 kPa irrigation threshold, with similar values for DSR and PTR. An irrigation threshold of 20 kPa was the optimum in terms of maximising grain yield, WP_I and WP_I+R for both PTR and DSR. Dry seeded rice with the 20 kPa threshold outperformed PTR-20 kPa in terms of WP_I through maintaining yield while reducing irrigation input by 30–50%.     

Evaluation and application of ORYZA2000 for irrigation scheduling of puddled transplanted rice in north west India

Water-saving technologies that increase water productivity of rice are urgently needed to help farmers to cope with irrigation water scarcity. This study tested the ability of the ORYZA2000 model to simulate the effects of water management on rice growth, yield, water productivity (WP), components of the water balance, and soil water dynamics in north-west India. The model performed well as indicated by good agreement between simulated and measured values of grain yield, biomass, LAI, water balance components and soil water tension, for irrigation thresholds ranging from continuous flooding (CF) to 70 kPa soil water tension.Using weather data for 40 different rice seasons (1970-2009) at Ludhiana in Punjab, India, the model predicted that there is always some yield penalty when moving from CF to alternate wetting and drying (AWD). With an irrigation threshold of 10 kPa, the average yield penalty was 0.8 t ha⁻¹ (9%) compared with CF, with 65% irrigation water saving, which increased to 79% at 70 kPa with a yield penalty of 25%. The irrigation water saving was primarily due to less drainage beyond the root zone with AWD compared to CF, with only a small reduction in evapotranspiration (ET) (mean 60 mm).There were tradeoffs between yield, irrigation amount and various measures of WP. While yield was maximum with CF, water productivity with respect to ET (WP_ET) was maximum (1.7 g kg⁻¹) for irrigation thresholds of 0 (CF) to 20 kPa, and irrigation water productivity (WP_I) increased to a maximum plateau (1.3 g kg⁻¹) at thresholds ≥30 kPa.Because of the possibility of plant stress at critical stages known to be sensitive to water deficit (panicle initiation (PI) and flowering (FL)), treatments with additional irrigations were superimposed for 2 weeks at one or both of these stages within the 10, 20 and 30 kPa AWD treatments. Ponding for two weeks at FL was more effective in reducing the yield penalty with AWD than ponding at PI, but the biggest improvement was with ponding at both stages. This reduced the average yield loss from 9% (0.8 t ha⁻¹) to 5% (0.5 t ha⁻¹) for AWD with thresholds of 10 and 20 kPa. However, maximum WP_I (1.1 g kg⁻¹) was achieved with an irrigation threshold of 20 kPa combined with more frequent irrigation at FL only, but with a greater yield penalty (8%). Thus the optimum irrigation schedule depends on whether the objective is to maximise yield, WP_ET or WP_I, which depends on whether land or water are most limiting. Furthermore, the optimum irrigation schedule to meet the short term needs of individual farmers may differ from that needed for sustainable water resource management.     

Estimation of paddy water productivity (WP) using hydrological model: an experimental study

Water productivity (WP) expresses the value or benefit derived from the use of water. A profound water productivity analysis was carried out at experimental field at Field laboratory, Centre for Water Resources, Anna University, India, for rice crop under different water regimes such as flooded (FL), alternative wet and dry (AWD) and saturated soil culture (SSC). The hydrological model soil-water-atmospheric-plant (SWAP), including detailed crop growth, i.e, WOFOST (World Food Studies) model was used to determine the required hydrological variables such as transpiration, evapotranspiration and percolation, and bio-physical variables such as dry matter and grain yield. The observed values of crop growth from the experiment were used for the calibration of crop growth model WOFOST. The water productivity values are determined using SWAP and SWAP–WOFOST. The four water productivity indicators using grain yield were determined, such as water productivity of transpiration (WP_T), evapotranspiration (WP_ET), percolation plus evapotranspiration (WP_ET+Q) and irrigation plus effective rainfall (WP_I+ER). The highest value of water productivity was observed from the flooded treatment and lowest value from the saturated soil culture in WP_T and WP_ET. This study, reveals that deep groundwater level and high temperature reduces the crop yield and water productivity significantly in the AWD and SSC treatment. This study reveals that in paddy fields 66% inflow water is recharging the groundwater. There is good agreement between SWAP and SWAP–WOFOST water productivity indicators.     

Applicability of APSIM to capture the effectiveness of irrigation management decisions in rice-based cropping sequence in the Upper-Gangetic Plains of India

Rice–wheat (RW) production system, which covers over 13.5 million ha in the Indo-Gangetic Plains of south Asia, is vital for food and nutritional security and livelihood of millions of poor people in this part of the region. Availability of irrigation water under projected climate change scenarios is a great concern, and demonstration of the impact of different irrigation regimes on rice, wheat, and system yields is essential to adopt suitable water saving technologies to minimize risk. This study tested the ability of the agricultural production systems simulator (APSIM) model to simulate the effects of different irrigation regimes on yield, irrigation water requirement, and irrigation water productivity (WP_i) of rice, wheat, and RW system in upper-gangetic plains of India. The long-term simulated rice yield showed a steadily declining trend at an average rate of 120 kg ha^?1 yr^?1 (R ² = 0.94, p < 0.05), while long-term simulated wheat yields showed a lower declining trend at an average rate of 48 kg ha^?1 yr^?1 (R ² = 0.48, p < 0.05). The highest WP_i of 8.31 kg ha^?1 mm^?1 was observed under RW system with the rice irrigation (IR) regime of 8 days alternate wetting and drying (AWD) and five irrigations for wheat with a yield penalty of 25.5 %. The next highest WP_i was observed in the treatment with a 5-day AWD regime in rice and five irrigations for wheat, with a yield penalty of 20.1 %. Thus, we can suggest that a 5-day AWD irrigation regime for rice combined with five irrigations during wheat could be the best option under water limiting situations.     

Phenological variations,yield differences and free proline accumulation in rice under alternate inundation and suspension of irrigation in Central Thailand

Pot and field experiments were conducted to investigate the phenological and physiological adjustments, yield performance and water productivity of rice under variable periods of suspension of irrigation. Four different water management schedules [viz. conventional water management (CWM), 2-week inundation followed by 2-week suspension of irrigation (I₂ S₂), 1-week inundation followed by 3-week suspension of irrigation (I₁ S₃), and 1-week inundation followed by 4-week suspension of irrigation (I₁ S₄)] were evaluated in greenhouse pots with transplanted rice. Only CWM, I₂ S₂, and I₁ S₃ were tested under field conditions. In the greenhouse pot experiment, the commencement of flowering and physiological maturity of rice occurred in the shortest period with CWM, and delayed with increasing the period of suspension of irrigation during vegetative phase. Some of shoot and root growth parameters of rice had significant differences among different water management practices. Free proline accumulated in leaves was lowest in CWM, increased with increasing the period of suspension of irrigation. The I₁ S₃ water management reported highest water productivity. Field experiment conducted, confirmed the results observed in the greenhouse experiment showing similar pattern of shoot and root growth characteristics and free proline accumulation in rice plants. The water productivity and grain yield was significantly higher in I₂ S₂ over CWM and I₁ S₃. Overall results suggest that the 2-week inundation followed by 2-week suspension of irrigation water management is a better option for water saving with higher yield in transplanted rice for 120 days old Suphan Buri 1 hybrid in Central Thailand.     

Yield response,water productivity,and seasonal water production functions for maize under deficit irrigation water management in southern Taiwan

As the challenges toward increasing water for irrigation become more prevalent, knowledge of crop yield response to water can facilitate the development of irrigation strategies for improving agricultural productivity. Experiments were conducted to quantify maize yield response to soil moisture deficits, and assess the effects of deficit irrigation (DI) on water productivity (water and irrigation water use efficiency, WUE and IWUE). Five irrigation treatments were investigated: a full irrigation (I₁) with a water application of 60 mm and four deficit treatments with application depths of 50 (I₂), 40 (I₃), 30 (I₄), and 20 mm (I₅). On average, the highest grain yield observed was 1008.41 g m^?2 in I₁, and water deficits resulted in significant (p < .05) reduction within range of 6 and 33%. This reduction was significantly correlated with a decline in grain number per ear, 1000-grain weight, ear number per plant, and number of grain per row. The highest correlation was found between grain yield and grain number per ear. The WUE and IWUE were within range of 1.52–2.25 kg m^?3 and 1.64–4.53 kg m^?3, respectively. High water productivity without significant reduction in yield (<13%) for I₂ and I₃ compared to the yield in I₁ indicates that these water depths are viable practices to promote sustainable water development. Also, for assessing the benefits of irrigation practices in the region crop water production functions were established. Maize yield response to water stress was estimated as .92, suggesting the environmental conditions are conducive for implementing DI strategies.     

氮水运筹对苏北平原稻茬麦干物质积累、产量和氮肥利用的影响

为明确苏北平原稻茬麦的最优氮水运筹模式,以淮麦30为材料,在大田测土施肥条件下,设置0 kg·hm^-2（N₀）、180 kg·hm^-2（N₁）、270 kg·hm^-2（N₂）3个施氮量和生育期不灌水（W₀）、灌拔节水（W₁）、灌拔节水+孕穗水（W₂）3个灌水处理,研究小麦干物质积累与转运、产量形成和氮素吸收与利用对不同氮水运筹的响应。结果表明,小麦干物质积累量、转运量和转运效率,氮素积累量、转运量和转运效率,花后干物质贡献率及氮素贡献率均随施氮量和灌水次数的增加而增加,各处理均以N₂W₂效果最佳。氮肥和灌水次数的增加对小麦成穗数、穗粒数、千粒重和产量、氮素收获指数与氮素利用效率均有显著促进作用,以N₂W₂效果最佳。氮肥农学效率、氮肥表观利用率和氮肥偏生产力则随施氮量增加而降低,以N₁W₂效果最佳;在相同氮肥水平下,灌水处理的上述三个指标较不灌水处理高。对本试验条件下各测定指标,氮肥在氮水运筹中起主导作用,且氮肥和灌水有显著的互作效应。综上,在苏北平原稻茬麦区,施氮量180 kg·hm^-2结合浇灌拔节水和孕穗水（W₂）的氮水模式可在协调小麦干物质和氮素的积累、转运与分配、促进增产的同时,提高氮肥利用效率,从而实现节氮增产的目标。     

冬小麦产量及土壤肥力的水氮调控效应

为了解水分和氮素调控对冬小麦产量及土壤肥力的影响,通过长期定位试验,设置0、150和225kg N·hm-2 3个施氮水平以及不灌水(CK)、越冬期灌水80mm(WF)、越冬期灌水40mm(WS)、秸秆覆盖+越冬期灌水40mm(MWS)、秸秆覆盖+拔节期灌水40mm(MJS)和拔节期灌水40mm(JS)6个水分调控模式,比较分析了不同水氮处理间小麦产量和土壤肥力的差异。结果表明,施氮可增加冬小麦产量,施氮量150与225kg N·hm-2的产量差异不显著(P0.05);水分调控模式中JS的产量最高,但与MJS差异不明显;水氮处理中,以施氮150kg N·hm-2条件下JS的产量最高。施氮降低了土壤速效磷和速效钾含量,但提高了速效氮、全氮和有机质含量;不同水分调控模式中MJS改善耕层土壤肥力的效果最佳;以施氮150kg N·hm-2水平下MJS处理的综合效应最好。     

Factors affecting irrigation water savings in raised beds in rice and wheat

Raised beds have been proposed for rice–wheat (RW) cropping systems in the Indo-Gangetic Plains as a means of increasing irrigation water productivity, among many other potential benefits. Field experiments were carried out in Punjab, India, during 2002–2006 to compare irrigation water use and productivity of transplanted rice and drill-sown wheat on fresh and permanent beds and conventionally tilled flats.     

Rice straw mulching and nitrogen response of no-till wheat following rice in Bangladesh

Wheat (Triticum aestivum L.) cultivation in no-till soil of a postrice harvest field utilizes residual soil moisture and reduces the time period from rice harvest to wheat seeding in intensive rice-wheat cropping systems. Some of the major constraints in no-till wheat production are high weed infestation, poor stand establishment due to rapid drying of topsoil and low nitrogen use efficiency (NUE). A field experiment was conducted at the research farm of the Wheat Research Centre, Dinajpur, Bangladesh, for two consecutive years to overcome those constraints, to evaluate rice straw as mulch, and to determine the optimum application rate of nitrogen (N) for no-till wheat. The treatments included 12 factorial combinations of three levels of mulching: no mulch (M₀), surface application of rice straw mulch at 4.0 Mg ha⁻¹ that was withdrawn at 20 days after sowing (M₁), the same level of mulch as M₁ but allowed to be retained on the soil surface (M₂), and four nitrogen levels (control 80, 120 and 160 kg ha⁻¹). Rice straw mulching had a significant effect on conserving initial soil moisture and reducing weed growth. Root length density and root weight density of wheat were positively influenced both by straw mulching and N levels. N uptake and apparent nitrogen recovery of applied N fertilizer were higher in mulch treatments M₁ and M₂ as compared to M₀. Also mulch treatment of M₁ and M₂ were equally effective at conserving soil moisture, suppressing growth of weed flora, promoting root development and thereby improved grain yield of no-till wheat. N application of 120 kg ha⁻¹ with straw mulch was found to be suitable for no-till wheat in experimental field condition.     

Effect of Phosphorus and Irrigation Levels on Yield,Water Productivity,Phosphorus Use Efficiency and Income of Lowland Rice in Northwest Pakistan

With decreasing availability of water for agriculture and increasing demand for rice production, an optimum use of irrigation water and phosphorus may guarantee sustainable rice production. Field experiments were conducted in 2003 and 2004 to investigate the effect of phosphorus and irrigation levels on yield, water productivity (WP), phosphorus use efficiency (PUE) and income of low land rice. The experiment was laid out in randomized complete block design with split plot arrangements replicated four times. Main plot consisted of five phosphorus levels, viz. 0 (P0), 50 (P50), 100 (P100), 150 (P150), and 200 (P200) kg/hm2, while subplots contained of irrigation times, i.e. 8 (I8), 10 (I10), 12 (I12), and 14 (I14) irrigation levels, each with a water depth of 7.5 cm. Mean values revealed that P150 in combination with I10 produced the highest paddy yield (9.8 t/hm2) and net benefit (1 231.8 US$/hm2) among all the treatments. Phosphorus enhanced WP when applied in appropriate combination with irrigation level. The highest mean WP [13.3 kg/(hm2?mm)] could be achieved at P150 with I8 and decreased with increase in irrigation level, while the highest mean PUE (20.1 kg/kg) could be achieved at P100 with I10 and diminished with higher P levels. The overall results indicate that P150 along with I10 was the best combination for sustainable rice cultivation in silty clay soil.     

Crop establishment method and irrigation schedule effect on water productivity,quality, economics and energetics of aerobic direct-seeded rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Rice is cultivated through transplanting of seedling in submerged field which is a cumbersome, labour intensive and water-guzzling practice. A field experiment was conducted to study the effect of crop establishment methods and irrigation schedules on water productivity, economics and energetics of aerobic direct-seeded rice at Punjab Agricultural University, Ludhiana, India, during Kharif 2012–2013. The experiment was laid out in split plot design, keeping combinations of two tillage system (no-tillage and conventional tillage) and two methods of sowing (uni-directional and bi-directional) in main plots and four irrigation schedule [(30, 45, 60 and 75 mm CPE (cumulative pan evaporation)] in sub plots. Aerobic direct-seeded rice sown after conventional tillage gave significantly higher grain yield than no-till with 15.4 % higher water expense efficiency. The energy gain and net monetary returns were 13.2 and 21.2 % higher in conventional sown crop than no-till, respectively. Bi-directional sowing resulted in 26.5 % higher grain yield than uni-directional with no effect on quality traits of grains. The net energy gain and net monetary returns were 26.5 thousands MJ/ha and 125.3 $/ha higher from bi-directional sown crop than uni-directional sown crop. Crop irrigated at 30 mm CPE schedule resulted in significantly higher grain yield than that irrigated at 45, 60 and 75 mm CPE. The energy gain, energy use efficiency and net returns were also maximum at 30 CPE schedule than at 45, 60 or 75 CPE. However, brown, milled and head rice recoveries were statistically at par between irrigation scheduling at 30 and 45 mm CPE but significantly better than 60 and 75 mm CPE. Bi-directional sowing with conventional tillage and irrigation at 30 CPE is an energy efficient and economical viable technique for direct-seeded rice.     

Effects of straw mulch on mungbean yield in rice fields with strongly compacted soils

In rice-based lowland areas in the Mekong region, the lack of full irrigation water availability for post-rice legume crops and the poor soil physical and chemical conditions are major constraints for development of sound rice/legume double cropping system. In order to improve legume productivity, use of rice straw mulch and various crop establishment methods were examined in two series of mungbean experiments in Cambodia where soils were coarse and strongly compacted. In one set of experiments conducted at four locations in the first year the effect of straw mulch, planting method (manual vs seed drill) and tillage method (conventional vs no-till) was examined. Another set of experiments were conducted in the second year at three locations with four levels of mulch under two planting densities. On average in year 1, mulching of rice straw at 1.5 t/ha increased mungbean crop establishment from 72 to 83%, reduced weed biomass from 164 to 123 kg/ha and increased yield from 228 to 332 kg/ha. Mulch was effective in conserving soil moisture, and even at maturity the mulched area had on average 1% higher soil moisture content. The amount of mulch between 1 and 2 t/ha did not show consistent effects in year 2, partly because some mulch treatments resulted in excessive soil moisture content and were not effective. Rice straw mulch had a significant effect on mungbean yield in 6 out of the 7 experiments conducted in two years, and mean yield increase was 35%. This yield advantage was attributed to better crop establishment, improved growth and reduced weed pressure, but in some cases only one or two of these factors were effective. On the other hand, planting method, tillage method and planting density had only small effects on mungbean yield in most experiments. Only in one location out of four tested, the no-till treatment produced significantly higher yield than the conventional method. Seed drill produced similar mungbean establishment and grain yield to the manual planting suggesting that the planter can be used to save the labour cost which is increasing rapidly in the Mekong region. Maximum root depth varied little with mulch or planting density, and was shallow (<20 cm) in all three locations where this character was determined. It is concluded that while rice straw mulch increased yield of mungbean following rice, the inability of mungbean roots to penetrate the hard pan is a major constraint for development of a sound rice/mungbean cropping system in the lowlands with compacted soils.     

An improved water-use efficiency for winter wheat grown under reduced irrigation

Single irrigation, compared to the conventional four or five irrigations, has been practised in northern China on winter wheat on a relatively large scale since 1991. In a field study, irrigation was reduced from normally four times (I₄, 4×75 mm) to one (I₁, 75 mm at the end of the second internode elongation) in an area with an annual rainfall of about 600 mm. A control without irrigation (I₀) was also included. Late sowing and early soil drying at seedling stage resulted in a relatively deep root system. Leaf area index, the size of upper leaves and the length of base internodes were also significantly reduced under I₁, but kernel number per panicle was not reduced, suggesting that the development of inflorescence was not disrupted. During the active grain-filling stage, it was found that leaf water potential under I₁ was maintained similar to that of I₄, while daytime stomatal conductance was substantially reduced. Leaf temperature was increased, indicating an inhibited leaf transpiration. Early senescence was induced in I₁ and I₀ crops and resulted in a substantially lower kernel weight. Although the grain yield of I₁ was reduced by about 15% from I₄, the water-use efficiency (WUE) for total water consumption was increased by 24–30%. Single irrigation can potentially make wheat cropping sustainable in this area in terms of water usage and prevent further depletion of the underground water resource. Explanations for the small or zero reduction in yield are: (1) the encouraging development of a deep root system that enabled the plants to use more water at depth (below 1 m), which is recharged annually by the relatively high summer rainfall. (2) A large portion of root system in the drying soil and its induced shoot physiological changes, that is, reduced leaf expansion and stomatal conductance, which helped the plants to establish a better canopy structure with a much reduced water consumption. (3) An improved harvest index.     

Effect of water management on dry seeded and puddled transplanted rice. Part 1: Crop performance

An alarming rate of ground water depletion and increasing labour scarcity are major threats to future rice production in north west India. Management strategies that reduce the irrigation amount and labour requirement while maintaining or increasing yield are urgently needed. Dry seeded rice (DSR) has been proposed as one means of achieving these objectives, but little is known about optimal water management for DSR. Therefore a field study was conducted on a clay loam soil in Punjab, India, during 2008 and 2009, to investigate the effects of irrigation management on the performance of puddled transplanted rice (PTR) and dry seeded rice. Irrigation scheduling treatments were based on soil water tension (SWT) ranging from ponding/saturation (daily irrigation) to alternate wetting and drying (AWD) with irrigation thresholds of 20, 40 and 70 kPa at 18–20 cm soil depth. Rainfall was above average and well distributed in 2008 (822 mm), and average and less well distributed in 2009 (663 mm).     

Potato growth with and without plastic mulch in two typical regions of Northern China

Plastic film mulching is an important agricultural practice to save water and improve crop productivity in Northern China. Three field experiments were conducted to examine the effect of plastic mulch on soil temperature, potato (Solanum tuberosum L.) growth and evapotranspiration under drip irrigation in two typical regions of Northern China in 2001 and 2006. Results suggest that daily mean soil temperature under mulch was 2–9 °C higher than without mulch, especially during the early growth. Potato growth was restrained under mulching conditions in the North China Plain mainly due to the higher air temperature in this region and thus the higher soil temperature. The negative effects of mulching included a lower emergence and fewer marketable tubers per plant. Evapotranspiration and potato tuber yield were both reduced by mulch, especially in the North China Plain. In northwest China, mulch favorably increased the weight of jumbo tubers (W ≥ 300 g) per plant. Mulching duration had little effect on potato evapotranspiration in northwest China. However, both tuber yield and water use efficiency (WUE) decreased with increases in mulch duration, which suggests the plastic mulch should be removed early.     

地膜玉米免耕轮作春小麦水氮生产力对灌水施氮水平的响应

针对绿洲灌区春小麦生产中水氮消耗量大、连作普遍问题,2015-2018年,在河西走廊甘肃农业大学绿洲试验站进行田间试验,设两种耕作措施(玉米茬免耕一膜两年用,NT;玉米茬传统翻耕,CT)、两种灌水水平(2400m^3·hm^-2,传统水平,I2;1920m^3·hm^-2,传统灌水减量20%,I1)和三种施氮水平(225kg·hm^-2,传统施氮,N3;180kg·hm^-2,减量20%施氮,N2;135kg·hm^-2,减量40%施氮,N1),分析了不同处理下春小麦籽粒产量、灌溉水生产力和氮肥偏生产力特征。结果表明,与CT、I2相比,NT和I1均能提高春小麦的籽粒产量、灌溉水生产力和氮肥偏生产力;与N3相比,N2的氮肥偏生产力提高11.6%~30.4%,籽粒产量和灌溉水生产力在2016、2017年均无显著变化,在2018年分别降低10.7%和10.4%;N1的籽粒产量降低6.1%~23.5%,灌溉水生产力和氮肥偏生产力分别增加6.1%~23.0%和27.6%~56.5%。在所有处理中,NTI1N2和NTI2N3处理的籽粒产量三年中均较高,二者间差异不显著,但NTI1N2处理灌溉水生产力和氮肥偏生产力较NTI2N3处理分别提高7.6%~20.4%和16.5%~30.4%;NTI1N2处理的籽粒产量、灌溉水生产力和氮肥偏生产力较CTI2N3处理分别提高3.8%~22.0%、19.7%~40.8%和29.7%~52.5%。综上所述,在西北绿洲灌区以覆膜玉米为前茬,免耕穴播小麦,配套施氮180kg·hm^-2、生育期灌水1920m^3·hm^-2的种植方式是适用于小麦节约水氮的高效生产模式。     

新型酸碱平衡剂对膜下滴灌水稻土壤盐渍化的改良效果及对产量的影响

土壤盐渍化加剧会导致稻田水肥利用效率下降,对水稻产量造成较大影响。针对这一现象,利用市场上已有的新型酸碱平衡剂,试验分析施用不同用量（7.5 kg/hm²、15.0 kg/hm²、22.5 kg/hm²）酸碱平衡剂后稻田土壤pH值和电导率的变化,及对膜下滴灌水稻产量的影响。结果表明,施用新型酸碱平衡剂能显著降低土壤pH值和电导率,且在20~30 cm土层改良效果最佳;显著提高了膜下滴灌水稻有效穗数,达到增产的目的。综合考虑施用后的经济效益,15.0 kg/hm²的用量较为适宜。     

减少灌水次数对河北冬性强筋小麦产量和品质的影响

为明确不同生态环境下减少灌水次数对冬性强筋小麦产量和品质的影响,以冬性强筋小麦品种农优3号和中麦998为材料,分别在冀中北生态区的徐水区和冀东生态区的昌黎县进行大田试验,设3个灌水次数处理(CK:越冬水+拔节水+开花水;W_2:越冬水+拔节水;W_1:越冬水),研究了不同灌水次数对冬性强筋小麦叶面积系数、干物质积累、籽粒产量和品质的影响。结果表明,随灌水次数减少,两个供试小麦品种孕穗期叶面积系数呈下降趋势,W_1处理显著低于其他处理;减少灌水次数导致2个冬性强筋小麦地上部的干物质积累量显著降低,而对收获指数的影响因品种而异,其中农优3号收获指数呈上升趋势,而中麦998以W_2处理最大。减少灌水次数使冬性强筋小麦有效穗数、穗粒数和千粒重显著降低,导致产量显著降低。灌水次数减少造成冬性强筋小麦籽粒容重和蛋白质含量提高,稳定时间延长,但湿面筋含量和沉降值下降。本研究条件下,徐水点农优3号的产量较高,而昌黎点中麦998的产量较高;相同灌水处理下,同一品种在昌黎点的品质指标优于徐水试验点。综上,在河北冬性强筋小麦种植区可以选用灌越冬水和拔节水协调其籽粒产量和品质。     

灌水次数和施磷量对冬小麦养分积累量和产量的影响

为给利用灌水和施肥措施调控小麦生长提供科学依据,在大田环境条件下,分别于2007-2008年（丰水年）在保定市、2008-2009年（平水年）在藁城市用当地冬小麦推广品种（河农822、冀5265）进行二因素裂区试验,研究了灌水次数（保证底墒的基础上设全生育期灌0、1、2和3次水3个灌水水平,分别用W0、W1、W2和W3表示）和施磷量（设0、75和150 kg·hm^-2 3个施磷水平,分别用P0、P1和P2表示）对小麦养分积累量和产量的影响。结果表明,灌水次数和施磷量对小麦植株的氮、磷、钾积累都有促进作用,但促进效果受降水年型的影响。丰水年灌水次数对氮、磷、钾积累量的影响较小,平水年灌水次数对氮、磷积累量的影响显著,氮、磷积累量在生育中后期都随灌水次数增加而提高,钾素积累量各生育时期受灌水影响不一致。丰水年施磷对氮素积累量影响不明显,磷素积累量随施磷量增加而增加,钾素积累量生育前中期以P0和P2较高,后期以P2较高;平水年,氮素和钾素积累量均随施磷量增加而增加,而磷素积累量受施磷量影响较小。适当灌溉和施磷可提高小麦养分生产效率、氮素和磷素收获指数,对钾素收获指数的影响较小。2年中灌水处理（W1、W2、W3）的籽粒产量均显著高于不灌水处理W0,但2007-2008年W1产量最高,2008-2009年则表现为W3>W2>W1。2年中P1和P2的籽粒产量均显著高于P0,但2007-2008年P1产量最高,2008-2009年P2产量最高,显示出磷素与水分的互补作用,即“水少磷多”或“水多磷少”都可以实现高产。根据研究结果,在河北平原常年降水（小麦全生育期100 mm左右）条件下全生育期灌溉2次,施P₂O₅ 150 kg·hm^-2;丰水年（200 mm左右）全生育期灌溉1次,施P₂O₅ 75 kg·hm^-2,可以取得较理想的产量。