System of rice intensification in promising rice hybrids in north-western Himalayas: crop and water productivity,quality, and economic profitability

System of Rice Intensification (SRI) has spread as an innovation of rice cultivation that can produce higher crop yields and conserve seed and water resources. The SRI innovation is also gaining popularity in north-western (NW) Himalayas on one hand and hybrid rice technology on the other in the region. Moreover, rice productivity in NW Himalayas is quite low owing to the use of low-yielding germplasm and poor crop management. Thus, SRI principles coupled with hybrid rice technology seems to be a boon to boost rice productivity in the irrigated ecosystem of wet-temperate NW Himalayas well known for rice cultivation. Therefore, comparative performance of promising rice hybrids under SRI was assessed at three locations in wet-temperate NW Himalayas (India) using nine promising rice hybrids including state-recommended rice hybrid “Arize–6129” as check cultivar. It was revealed that various hybrids differed significantly w.r.t. days to 50% flowering, days to 75% maturity, plant height, tillers hill^?1, panicles hill^?1, panicles m^?2, and panicle length. Highest number of panicles m^?2 (370) was observed in Arize–6129 followed by US–312, Bioseed–786, and NK–3325, respectively. Significantly longer panicles were observed in Dhanya–2366 followed by Arize–6129, US–312, Bioseed–786, NK–3325, and US–10, respectively. Arize–6129 resulted in significantly higher grain (75 q ha^?1) and straw yield (125 q ha^?1) followed by US–312, Dhanya–2366, NK–3325, PAC–801, US–10, Bioseed–786, Uday–111, and Uday–131, respectively. The production- and monetary-efficiency as well as gross and net returns and B:C ratio also followed the similar trend as that of crop productivity with significantly higher production– (67 kg ha^?1 day^?1) and monetary–efficiency (INR 608.4 ha^?1 day^?1), and net returns (INR 68138 ha^?1) and B:C ratio (3.66) in check cultivar “Arize–6129” over other rice hybrids. Higher grain productivity (49.5–75.0 q ha^?1), net returns (INR 39238–68138 ha^?1), and B:C ratio (2.53–3.66) in current study conclusively inferred that SRI coupled with hybrid rice technology can harness higher productivity and profitability. Protein content (8.30–8.45%) exhibited higher values under Bioseed–786 followed by NK–3325, UDAY–111, and Arize–6129; however, NPK uptake (grains, straw, total) was significantly highest in Arize–6129 followed by US–312, Dhanya–2366, and NK–3325, respectively. Total water productivity (6.4–9.75 kg ha^?1 mm^?1), irrigation water productivity (16.5–25 kg ha^?1 mm^?1), and economic water productivity (64.0–97.5 INR ha^?1 mm^?1) collectively followed the trend of Arize–6129 > US–312 > Dhanya–2366 > NK–3325 > US–10 > PAC–801 > Bioseed–786 > Uday–111 > Uday–131 in current study. Overall, Arize–6129, US–312, and Dhanya–2366 were proved as potential rice hybrids in terms of their higher crop and water productivity and economic profitability among above nine rice hybrids for their large-scale cultivation under SRI in wet-temperate NW Himalayas.     

华北平原不同降水年型和作物种植模式下的产量和耗水模拟

华北平原是中国重要的粮食生产基地,在国家粮食产业中地位较高,但长期灌溉造成了华北平原地下水资源的严重亏损,地下水位持续下降。该研究利用APSIM模型对华北平原1986－2015年不同种植模式下的产量和耗水情况进行模拟研究,为华北平原调整作物种植模式、农业水资源管理以及农业发展政策的制定提供科学依据。研究结果表明：APSIM模型能够较好地模拟冬小麦和夏玉米的生育期、产量及水分利用特征,其中生育期模拟结果的误差在5 d之内,产量、ET和下渗量模拟结果的R2均在0.84以上,表明该模型在华北平原具有较好的适用性;在华北平原地区,冬小麦-夏玉米一年两熟种植模式（M2Y1）年均产量（13 445 kg/hm2）最高,但耗水量（724 mm）也是最大,水分亏损（233 mm）最为严重;一年一熟种植模式（M1Y1）年均耗水量（534 mm）较小,水分亏损量（43 mm）最少,但产量（9 215 kg/hm2）较低;两年三熟种植模式（M3Y2）兼顾产量和耗水,在保证一定产量的前提下减少了耗水量,产量耗水综合效果最好,适合在华北平原推广实行。此外,该研究对栾城站丰水年、平水年和枯水年等不同降水年型下的3种种植模式产量耗水特征进行了对比分析,研究表明在华北平原降水资源对于作物生长有重要意义,年降水量越大,作物产量越高,水分亏损量越少。     

黄土高原地区苜蓿生产力动态及其土壤水分消耗规律

为了解不同生长年限苜蓿生产力及土壤水分的变化特征,该文系统研究了黄土高原地区3年、4年、6年、8年、12年、18年及26年生紫花苜蓿生产力动态及土壤水分的消耗规律。结果表明：不同生长年限苜蓿鲜草产量存在极显著差异。苜蓿草地土壤水分呈现规律性的变化：随土层深度的增加,土壤含水率增加,300cm土层以下,土壤含水率变化趋势平缓。苜蓿生长超过18年,上层土壤水分开始恢复,但深层土壤通体干化,水分难以恢复。苜蓿水分利用效率随生长年限的延长而降低。研究表明在黄土高原半湿润区紫花苜蓿适宜的生长年限为8年,第6年为苜蓿的生长高峰期。     

Amelioration of Acidic Soil and Production Performance of Cowpea by the Application of Different Organic Manures in Eastern Himalayan Region,India

Acidic soils are limiting the production potential of the crops because of low availability of basic ions and excess of hydrogen (H⁺), aluminium (Al³⁺), and manganese (Mn²⁺) in exchangeable forms. Therefore, a field study was conducted to know the ameliorating effect of organic manures on acidic soils and production performance of cowpea (Vigna unguiculata L., Walp.) by using different locally available organic manures. Growth and yield attributes were observed to be significantly greater with vermicompost (VC) followed by poultry manure (PM). Porosity, maximum water-holding capacity (MWHC), and organic carbon were greater with farmyard manure (FYM) and cow dung manure (CDM). However, water retention at field capacity (FC), permanent wilting point (PWP), bulk density (BD), pH, and availability of nitrogen (N), phosphorus (P), and potassium (K) were greater with VC. However, physical and chemical properties were deteriorated in control plots.     

Influence of municipal compost on temperature, water, nutrient status and the yield of maize in a temperate soil

Abstract. Composted domestic waste was applied either as a mulch or was incorporated into the topsoil. Mulching reduced the seasonal midday soil temperature ranges from between 14 °C and 27.5 °C to between 14 °C and 26 °C, averaging a 0.6 °C fall. However, at sub-optimal temperatures for maize production under the temperate conditions of South East England, the difference may be critical. Compost mulch also improved soil-water conservation in an average year, but not in a very dry year. Compost application increased soil-available N, but increased K uptake was considered to be more important for crop yield than either N additions or the effect on retained soil water. Overall, compost applied as a surface mulch, or incorporated into medium-textured soils in the south and east of England increased crop yield.     

Impact of boron fertilization on boron fractions at different crop growth stages in cauliflower_cowpea_okra sequence in an inceptisols of North East India

Abstract

A field experiment was conducted at Horticultural Experimental Farm, Assam Agricultural University, Jorhat during the year 2015–17 to assess the impact of boron fertilization on dynamics of boron fractions in soil and crop yields in cauliflower–cowpea–okra cropping sequence. Five levels of boron (0, 0.5, 1.0, 1.5 and 2.0?kg ha^?1) along with the recommended dose of NPK fertilizer were applied in soil in cauliflower once in each 2 years (2015–17) of experimentation to assess the direct effect of boron fertilization, while cowpea and okra were grown as a suceeding test crop to study the residual effects of boron fertilization in the cropping sequence. Among the different levels of boron, the highest content of all the boron fractions in soil was recorded at rate of 2?kg B ha^?1 at different crop growth stages for all the three crops. Progressive decrease in content of all the boron fractions with crop ageing was noticed. The content of different boron fractions in soil follows the order readily soluble boron (RSB)<oxide bound boron (OXB)<organic bound boron (ORBB)<specifically adsorbed boron (SAB) <residual boron, respectively. The boron level of 2?kg B ha^?1 was found to prominent in increasing the yield in all the crops. In respect of contributions of different boron fractions to yield of crops, oxide bound boron(2.10) was found to be the highest contributor of cauliflower yield, while the residual boron (1.10), contributed the highest to cowpea yield and organic bound boron fraction (1.24) was found to be most prominent contributor of boron in leveraging okra yield.     

Impact of precursor crop and nitrogen fertilizer on the productivity of finger millet based cropping system and soil fertility in Lake Tana basin of Ethiopia

Abstract

Traditional short-term diversification of annual crops for the purpose of improving soil fertility and food security is a common practice in Ethiopia. However, the best cropping systems have not been selected yet though field research. Experiments were conducted for two years with an objective of establishing sustained finger millet based short term cropping sequence in two major finger millet producing areas of Ethiopia. The experiments were laid out in a split-plot arrangement with six precursor crops (haricot bean, maize, sweet lupine, niger seed, wheat, and teff) as a main plot factor, where determined residues were retained in the main plot after harvesting and two nitrogen fertilizer levels (30 and 60?kg ha^?1) applied for finger millet as sub-plots with three replications. Soil analysis result examined immediately after finger millet harvest showed a significant effect of precursor crops and nitrogen fertilizer rates on soil properties. Planting finger millet following lupine increased the soil organic carbon, total nitrogen and cation exchange capacity by 17.37%, 65.50%, 26.15%, respectively, over planting finger millet following teff. Use of different amount of nitrogen fertilizer likely contributed to observed differences in residual soil nutrients. Accordingly, finger millet following lupine with the addition of 60?kg ha^?1 nitrogen fertilizer gave significantly higher finger millet grain yield (3.24 tone ha^?1) and relative production (22.37%) and economic (40.7%) efficiency. This system with their high sustainability and multiple benefits can be readily accepted by the farming community.     

Phosphorus skipping effect on productivity,profitability and sustainability of rice-wheat cropping systems in Indo-Gangetic plains of India

A field experiment was conducted for eight years at ICAR-Indian Institute of Wheat and Barley Research, Karnal, Haryana, India to study the skipping effect of P application on productivity, profitability and sustainability of rice-wheat cropping system. Rice yield and biomass were 8.35% and 6.6% higher where cowpea was grown after wheat compared to rice-vegetable pea-wheat crop sequence, respectively. Phosphorus application to rice or wheat or both crops exhibited at par rice grain yield, biomass, harvest index. Phosphorus application to both crops or only in rice crop produced maximum and significantly higher wheat yield (4.62 t ha^?1) as compared to P application only to wheat (4.48 t ha^?1). Eight years growing of green gram, cowpea and vegetable pea increased the organic carbon content 42.89, 16.38 and 4.57 %, respectively compared to the initial level. Skipping of P to either crop, by considering 13.5 million ha rice-wheat area, will save approximately Rs 40,500 million (Rs = Indian rupee) or US $ 623 million ($ = Rs 65) per year. Air pollution may be checked, due to saving on diesel in transportation of P fertilizer, to the tune of 60,383 tonnes of CO₂ per year by reducing emission of one of important global warming gas.     

华北平原旱地不同熟制作物产量、效益和水分利用比较

针对华北平原地下水超采严重,通过研究雨养旱作条件下不同熟制的产量、投入产出和水分利用效率,探索华北平原缺水区雨养旱作条件下的节水种植制度,可为地下水超采提供技术支撑。以当地主栽种植模式冬小麦和夏玉米一年2熟种植和春玉米一年1熟种植为研究对象,通过大田试验对雨养旱作条件下冬小麦、夏玉米和春玉米3种作物构成的2种种植制度的产量、耗水、投入、产出进行分析。试验于2007—2013年在中国科学院栾城农业生态系统试验站进行,该站为华北平原高产农区的典型代表。试验共设2个处理,T1为冬小麦-夏玉米一年2熟制,T2为春玉米一年1熟制。T1中的冬小麦生育期为每年的10月中上旬至翌年的6月中旬,夏玉米为6月中下旬至10月上旬,冬小麦品种大部分年份为‘科农199’,夏玉米品种为‘郑单958’。T2中春玉米的生育期为每年的5月中下旬至当年的9月上中旬,品种为‘农大108’、‘浚单20’、‘郑单958’和‘先玉335’。试验区从2007年9月至2013年6月一直未灌溉,为雨养旱作条件。研究结果表明,雨养旱作条件下,冬小麦产量基本稳定;夏玉米和春玉米产量随年型不同波动较大,尤其是夏玉米产量受播种时土壤含水量的影响较大,很多年份由于干旱少雨,玉米出苗时间推迟,导致玉米产量大幅度降低。T1比T2虽然具有明显的产量优势,增产34.1%,但由于冬小麦生产投入较高,T1的净收益比T2低279.97元·hm-2。3种作物的生产投入中,农资和机械投入比例最大,劳动力投入占很小比例,农资投入中,化肥投入最高;3种作物的产投比分别为1.42、2.66和3.42,雨养旱作条件下冬小麦的产投比最低,春玉米最高。从作物的耗水结构分析,冬小麦生育期降雨较少,以消耗雨季储存于土壤中的土壤水分为主,春(夏)玉米生育期降雨较多以消耗降雨为主。目前,生产上正在自发地压缩冬小麦的种植面积,春玉米一年1熟种植面积迅速增加。因此,在保证区域粮食安全的条件下,通过调整农业种植结构可以控制水资源的过度开采,保证农业持续发展。     

Cropping sequence and nitrogen fertilizer effects on the productivity and quality of malting barley and soil fertility in the Ethiopian highlands

The productivity and quality of malting barley were evaluated using factorial combinations of four preceding crops (faba bean, field pea, rapeseed, and barley) as main plots and four nitrogen fertilizer rates (0, 18, 36, and 54 kg N ha^?1) as sub-plots with three replications at two sites on Nitisols of the Ethiopian highlands in 2010 and 2011 cropping seasons. Preceding crops other than barley and N fertilizer significantly improved yield and quality of malting barley. The highest grain yield, kernel plumpness, protein content, and sieve test were obtained for malting barley grown after faba bean, followed by rapeseed and field pea. Nitrogen fertilizer significantly increased yield, protein content, and sieve test of malting barley. All protein contents were within the acceptable range for malting quality. Inclusion of legumes in the rotation also improved soil fertility through increases in soil carbon and nitrogen content. We conclude that to maximize yield and quality of malting barley, it is critical to consider the preceding crop and soil nitrogen status. Use of appropriate break crops may substitute or reduce the amount of mineral N fertilizer required for the production of malting barley at least for one season without affecting its quality.     

Conservation tillage and mulching effects on the adaptive capacity of direct-seeded upland rice (Oryza sativa L.) to alleviate weed and moisture stresses in the North Eastern Himalayan Region of India

A field experiment was conducted to study the effects of tillage and mulch on weed growth, soil moisture storage, productivity and profitability of upland rice during 2012–2013 at Lembucherra, India. Tillage treatments included CT-RI: conventional tillage with 100% residue incorporation and NT-RR: no-till with 100% residue retention. Mulches included rice straw (SM), Gliricidia (GM), brown manuring (BM) and none (NM). CT-RI registered the highest total weed density (89–168 weeds m^?2) and biomass (9.6–183 g dry weight m^?2) than those for the NT-RR (75–161 weed m^?2 and 8–155 g dry weight m^?2). In addition, NT-RR stored (122–172 mm) more soil moisture (0–40 cm soil depth) in comparison with that for the CT-RI treatment (110–161 mm) during crop growing season. Tillage treatments did not have the significant effect on yields. NT-RR reduced the cost of cultivation by 31.5% compared with that for the CT-RI. Thus, the net returns under NT-RR were more than those for the CT-RI. The BM recorded the lowest weed biomass and density as compared to that under other mulches. Therefore, cultivation of upland rice using NT along with BM mulching enhanced productivity and profitability of rice cultivation in India.     

Tree biomass,resource use and crop productivity in agri-horti-silvicultural systems in the dry region of Rajasthan,India

A combination of silvicultural species [Prosopis cineraria (L.), Ailanthus excelsa Roxb. and Colophospermum mopane (J. Kirk ex Benth.)] were planted with horticultural species [Ziziphus mauritiana (L.), Cordia myxa (Forster), and Emblica officinalis (Gaertn)] and intercropped with wheat (Triticum aestivum). Z. mauritiana +P. cineraria combination produced greater fruit, fodder and fuel wood and was less competitive to wheat crop. Crop yield reduced by 5% to 23% in the agroforestry systems than the yield in sole crop plot. Lowest yield was in C. mopane + C. myxa combination. Fodder yield was 0.53, 0.20 and 0.07 t ha^?1 from C. mopane (cursive), P. cineraria and A. excelsa, respectively, whereas utilizable biomass was 2.63 t ha^?1 from C. myxa (cursive) + P. cineraria, 2.21 t ha^?1 from C. myxa (cursive) + C. mopane and 2.18 t ha^?1 from Z. mauritiana + P. cineraria combinations. Soil organic carbon and NH₄–N increased (by 7% and 8%, respectively), whereas NO₃–N and PO₄–P decreased in agroforestry compared to the sole tree plots. Primary root attributes of P. cineraria, A. excelsa and C. mopane were higher in agroforestry and mostly concentrated in the top 0–25 cm of the soil layer. Z. mauritiana + P. cineraria were the best combination with minimum yield reduction and were found to be beneficial in enhancing soil fertility.     

Impact of organic‐manure combinations on the productivity and soil quality in different cropping systems in central India

In a field experiment, the effect of combination of different organic manures on the productivity of crops and soil quality were evaluated in deep vertisols of central India. Combinations of cattle dung manure (CDM), poultry manure (PM), and vermicompost (VC) vis‐à‐vis mineral fertilizers were tested in four cropping systems involving soybean (Glycine max L.), durum wheat (Triticum durum Desf.), mustard (Brassica juncea L.), chickpea (Cicer arietinum L.), and isabgol (Plantago ovata Forsk). The organic manures were applied based on the N‐equivalent basis and nutrient requirement of individual crop. The grain yields of durum wheat and isabgol were higher in the treatment that received a combination of CDM + VC + PM whereas in mustard, CDM + PM and in chickpea, CDM + VC recorded the higher yields. The yield levels in these organic‐manure combinations were similar to the yields obtained with mineral fertilizers. Among the cropping systems, soybean–durum wheat and among the nutrient sources, the combination of CDM + VC + PM recorded the highest total productivity. At the end of the 3‐year cropping cycle, application of organic manures improved the soil‐quality parameters viz., soil organic carbon (SOC), soil available nutrients (N, P, and K), soil enzymes (dehydrogenase and alkaline phosphatase), and microbial biomass C in the top 0–15 cm soil. Bulk density and mean weight diameter of the soil were not affected by the treatments. Among the cropping systems, soybean–durum wheat recorded the highest SOC and accumulated higher soil available N, P, and K. In conclusion, the study clearly demonstrated that the manures applied in different combinations improved the soil quality and produced the grain yields which are at par with mineral fertilizers.     

Plastic film mulching on soil water and maize (Zea mays L.) yield in a ridge cultivation system on Loess Plateau of China

Plastic film mulching has commonly been used for adaptation to water scarcity and for increasing agricultural productivity on the semiarid Loess Plateau of China. However, the effect of plastic film mulching on cropland soil water and thermal regimes on the semiarid Loess Plateau of China is not well understood. This study simultaneously monitored the dynamics of the soil water content and the soil temperature with high resolution in a ridge cultivation system with plastic film mulching (RS) and a flat cultivation system without plastic film mulching (FS) during the maize (Zea mays L.)-growing season. We found that, in general, the soil temperature and soil water content were significantly different among the ridge under RS (RS-ridge), the furrow under RS (RS-furrow) and FS throughout the maize-growing season (P < 0.05). Plastic film mulching increased the near-surface soil temperature by approximately 1°C throughout the study period. RS significantly increased the soil water content during the dry period (May to June), especially within the middle soil layer (30–60 cm), compared to FS. The lowest monthly average soil water content was found at a depth of 30–60 cm layer in FS during the dry period (May and June). The water depletion was found within deeper (100–160 cm) soil layers in May but the water storage in the same layer of FS in June increased although it was the dry period, which differed from RS. The RS practices showed a longer period of water supply from the deeper soil layer (100–160 cm) in May and June for meeting maize water demands during the early growing stage rather than in only May for FS. During June (dry period), the water storage at a depth of 0–60 cm was greater in RS than in FS, and the reverse was true at a depth of 60–160 cm. The results indicate that the dry soil layer at a depth of 30–60 cm formed during June in FS likely reduced water movement from deeper layers to the topsoil layer, and hence constrained the availability of surface soil water for meeting maize water requirements during the early growing stage (dry period). Our study suggests that RS tends to significantly increase surface soil water availability by restraining the formation of a dry soil layer during the early maize-growth stage primarily under dry conditions, and thus enhances maize productivity in the semiarid Loess Plateau of China.     

Long-term effects of lantana residue additions on water retention and transmission properties of a medium-textured soil under rice–wheat cropping in northwest India

Abstract. Hydraulic properties of soils after rice cropping are generally unfavourable for wheat cultivation. Poor drainage, delayed planting and oxygen stress in the root zone may adversely affect the wheat crop after lowland rice cultivation. We studied long-term effects of lantana ( Lantana spp. L.) residue additions at 10, 20 and 30 t ha⁻¹ yr⁻¹ (fresh biomass) on physical properties of a silty clay loam soil under rice–wheat cropping in northwest India. At the end of ten cropping cycles, soil water retention, infiltration rate, saturated hydraulic conductivity and drying rate of soil increased significantly with lantana additions. The available water capacity (AWC), on volume basis, declined at rice harvest (from 22.0 to 18.8–20.9%), but increased at wheat harvest (from 12.9 to 13.4–15.0%) after lantana treatment. The volumes of water transmission (>50 μm) and storage pores (0.5–50 μm) were greater, while the volume of residual pores (<0.5 μm) was smaller in lantana-treated plots than in controls at both rice and wheat harvest. Infiltration rate in the lantana-treated soil was 1.6–7.9 times that of the control (61 mm d⁻¹) at rice harvest, and 2–4.1 times that of the control (1879 mm d⁻¹) at wheat harvest. Thus lantana addition improved soil hydraulic properties to the benefit of the wheat crop in a rice–wheat cropping sequence.     

The productivity and energy potential of alfalfa,fodder galega and maize plants under the conditions of the nemoral zone

This study aimed to investigate the productivity of two C3 legumes – alfalfa (Medicago sativa L.) and fodder galega (Galega orientalis Lam.) – and the feasibility of their use as renewable energy resources. Maize (Zea mays L.), a well-established bioenergy crop belonging to the C4 plant group, was used as a baseline in comparison. Field trials were conducted at the Institute of Agriculture at the Lithuanian Research Centre for Agriculture and Forestry during the period 2012–2013. The perennial forage legumes were grown without mineral or organic fertilizers. The maize was grown (a) without and (b) with nitrogen fertilizers. The perennial forage legumes were harvested three times per growing season. Carbon (C), nitrogen (N) and sulphur (S) contents of biomass were determined by using a dry combustion method. The calorific value of biomass was determined by a combustion method using an IKA bomb calorimeter. The largest share of the total annual yield of biomass of perennial forage legumes was obtained from the first cut and amounted to 54% and 57% for alfalfa and fodder galega, respectively. The S content of biomass was similar in all crops investigated, but the N content was higher in perennial forage legumes. Biomass C content did not differ between the crops, but the C:N ratio was widely varied – from 28–35 in fertilized maize, to 16–17 in alfalfa and 15–16 in fodder galega. This study showed that alfalfa and fodder galega can be grown as energy crops under less intensive management; however, the specific chemical composition of biomass should be considered before choosing the most appropriate conversion process.     

Effect of lime water – manure organic fertilizers on the productivity,energy efficiency and profitability of rainfed maize production

ABSTRACT

Agro-industrial activities such as livestock production and maize processing generate large amounts of waste that can pollute the environment if not treated. To reduce the environmental impact of such wastes, the use of nejayote and ovine manure as fertilizers in maize production was evaluated in terms of yield (GY), energy efficiency (EE) and benefit-to-cost ratio (BCR), during 2015 and 2016. A factorial experiment was designed combining nejayote (0, 75 and 150 m³ ha^?1) with manure (0, 25 and 50 Mg ha^?1), those treatments were compared with a chemical fertilizer treatment (120N–60P–30K); treatments were done in three replicates. Nejayote-manure fertilizers were characterized physical and chemically. Inputs and outputs used/obtained during the production cycle were registered in terms of their energy equivalents and economic value. At the end of each cycle GY, EE and BCR were calculated. Results showed that nejayote-manure mixtures were 19% more energy efficient and produced a yield 12% greater than chemical fertilization (P = 0.001), thus generating a BCR of 6.3 (P = 0.023). Organic fertilizers were useful as waste treatments and produced greater benefits than chemical fertilizers. Additionally, the water recovered from nejayote was enough to provide a 7.5 or 15 mm of gross irrigation during the crop cycle.     

Integral energy of conventional available water, least limiting water range and integral water capacity for better characterization of water availability and soil physical quality

Different approaches have been proposed for quantification of soil water availability for plants but mostly they do not fully describe how water is released from the soil to be absorbed by the plant roots. A new concept of integral energy (E_I) was suggested by Minasny and McBratney (Minasny, B., McBratney, A.B. 2003. Integral energy as a measure of soil-water availability. Plant and Soil 249, 253-262) to quantify the energy required for plants to take up a unit mass of soil water over a defined water content range. This study was conducted to explore the E_I concept in association with other new approaches for soil water availability including the least limiting water range (LLWR) and the integral water capacity (IWC) besides conventional plant available water (PAW). We also examined the relationship between E_I and Dexter's index of soil physical quality (S-value). Twelve agricultural soils were selected from different regions in Hamadan province, western Iran. Soil water retention and penetration resistance, Q, were measured on undisturbed samples taken from the 5-10 cm layer. The PAW, LLWR and IWC were calculated with two matric suctions (h) of 100 and 330 hPa for field capacity (FC), and then the E_I values were calculated for PAW, LLWR and IWC. There were significant differences (P < 0.01) between the E_I values calculated for PAW₁₀₀, PAW₃₃₀, LLWR₁₀₀, LLWR₃₃₀ and IWC. The highest (319.0 J kg⁻¹) and the lowest (160.7 J kg⁻¹) means of E_I were found for the E_I(IWC) and E_I(PAW330), respectively. The E_I values calculated for PAW₁₀₀, LLWR₁₀₀ and LLWR₃₃₀ were 225.6, 177.9 and 254.1 J kg⁻¹, respectively. The mean value of E_I(PAW330) was almost twice as large as the mean of E_I(IWC) showing that IWC is mostly located at lower h values when compared with PAW₃₃₀. Significant relationships were obtained between E_I(IWC) and h at Q = 1.5 MPa, and E_I(LLWR100) or E_I(LLWR330) and h at Q = 2 MPa indicating strong dependency of E_I on soil strength in the dry range. We did not find significant relationships between E_I(PAW100) or E_I(PAW330) and bulk density (ρ_b) or relative ρ_b (ρ_b-rel). However, E_I(LLWR100) or E_I(LLWR330) was negatively and significantly affected by ρ_b and ρ_b-rel. Both E_I(PAW100) and E_I(PAW330) increased with increasing clay content showing that a plant must use more energy to absorb a unit mass of PAW from a clay soil than from a sandy soil. High negative correlations were found between E_I(PAW100) or E_I(PAW330) and the shape parameter (n) of the van Genuchten function showing that soils with steep water retention curves (coarse-textured or well-structured) will have lower E_I(PAW). Negative and significant relations between E_I(PAW100) or E_I(PAW330) and S were obtained showing the possibility of using S to predict the energy that must be used by plants to take up a unit mass of water in the PAW range. Our findings show that E_I can be used as an index of soil physical quality in addition to the PAW, LLWR, IWC and S approaches.     

东北农场农作物生长季土壤呼吸对温度和含水量的响应

通过静态碱液吸收法测定了东北典型农场水稻和玉米两种农作物在生长期（4—7月）的土壤呼吸速率及其变化规律,分析了不同深度的土壤呼吸速率对土壤温度和土壤含水量的响应。结果表明:在作物生长期,水稻样地的土壤呼吸速率高于玉米样地。水稻和玉米样地在0—15 cm深度的土壤呼吸速率明显高于15—30 cm和30—60 cm。随着土壤深度的增加,土壤呼吸速率逐渐减小。水稻土壤的呼吸速率最大值为580.6 μg/（kg·h）,最小值为160.4 μg/（kg·h）;而玉米的土壤呼吸速率最大值为565.3 μg/（kg·h）,最小值为137.5 μg/（kg·h）。水稻和玉米样地土壤呼吸速率与土壤温度呈现极显著相关关系（p<0.01）,土壤温度曲线在4月到6月初明显上升,而土壤呼吸速率曲线在这一时段也呈相同态势;6月下旬到7月初土壤温度变化平稳,土壤呼吸速率与土壤温度的同步变化趋势不明显。同时,两种作物的土壤含水量与土壤呼吸速率间的相关性也极为显著（p<0.01）,说明土壤含水量也能够解释生长期水稻和玉米的土壤呼吸速率变化。     

耕作方式对华北冬小麦.夏玉米周年产量和水分利用的影响

在冬小麦季设置秸秆不还田翻耕(CT)、秸秆还田翻耕(CTS)、秸秆还田旋耕(RTS)和免耕秸秆覆盖(NTS)4种处理,研究耕作方式对华北小麦-玉米两熟区作物周年产量和水分利用的影响。结果表明:耕作方式对当季冬小麦产量和水分利用影响显著,对夏玉米产量和水分利用影响不大,但秸秆还田提高了夏玉米产量。RTS、CTS、CT 3个处理小麦季产量差异不显著,而NTS由于有效穗数不足,产量显著低于其他处理;与CT相比,NTS周年产量平均减产5.13%,RTS增产2.69%,CTS增产2.33%。耕作方式对当季小麦土壤水分含量影响大,而对后茬夏玉米土壤水分含量的影响较小。NTS提高了小麦季土壤水分含量,增加了土壤储水量,与CT相比,0~60 cm土壤储水量2010年和2011年分别增加39.07 mm和26.65 mm。从耗水构成来看,土壤水在冬小麦耗水中所占比例最大,其次为灌水和降水;而夏玉米耗水以降水为主,且降水中有一部分转化为土壤水储存起来。NTS提高了冬小麦季土壤储水量,降低了土壤水分的消耗,冬小麦季耗水最少。与CT相比,NTS小麦季平均节水22.40 mm,周年耗水量也以NTS最少;但NTS冬小麦产量降低导致其小麦季和周年水分利用效率均最低。从作物周年产量和水分利用的角度来看,如何提高免耕秸秆覆盖小麦季产量,进而提高周年产量,发挥其节水优势,是该耕作模式在华北地区冬小麦?夏玉米两熟区推广应用亟需解决的关键问题。