Estimation of reference evapotranspiration and crop coefficient in wheat under semi-arid environment in India

Abstract

The comparison of six standard reference evapotranspiration (ETo) estimate models was carried out with measured lysimeter evapotranspiration (ETc) in wheat crop in a semi-arid environment at Rahuri, India. The globally accepted reference evapotranspiration model of FAO 56 Penman Monteith underestimated the references ETo by 19.2% (420.5 mm) over lysimeter ET (520.7 mm). Out of the remaining five models, the Hargreaves model ranked first and was overestimated by 6.5% followed by the Blaney Criddle model (underestimated by ?5.6%). The references ETo by pan evaporation model underestimated the reference ETo to the extent of ?28.8%. The influence of statistical indicators like RMSE, MBE which was computed by considering Lysimeter ETc as standard, was quite low in the Hargreaves model compared to the rest of the models and hence, the Hargreaves method is quite acceptable for ETo estimates as this method requires much less climatic parameters (temperature and extraterrestrial radiation) than Penman Monteith (FAO56) and Modified Penman of FAO 24 as these models require aerodynamic and radiation terms, besides additional physical terms in former models of ETo estimates. The seasonal crop coefficients were 1.24, 1.13, 0.94, 0.85, 1.06 and 1.40 in Penman Monteith, Modified Penman, Hargreaves, Radiation balance, Blaney Criddle and Pan Evaporation models, respectively.     

基于修正双作物系数模型估算温室黄瓜不同季节腾发量

为估算温室黄瓜植株蒸腾与土面蒸发,该研究基于FAO-56推荐的双作物系数模型,应用温室内实测微气象、叶面积指数(LAI)及土壤水分数据,对模型中基础作物系数(Kcb)和土面蒸发系数(Ke)进行修正,并基于修正后FAO-56Penman-Monteith(P-M)模型,确定温室参考作物蒸发蒸腾量(ET0),进而估算温室黄瓜蒸发蒸腾量(ETc)和植株蒸腾(Tr)。基于Venlo型温室内黄瓜不同种植季节(春夏季和秋冬季)Lysimeter和茎流计观测的黄瓜ETc和Tr,对修正后的双作物系数模型预测结果进行验证。结果表明,应用修正后的双作物系数模型估算的温室黄瓜ETc和Tr与实测值具有较好地一致性,春夏季温室黄瓜全生育期ETc估算值与实测值的日均值分别为3.05和2.94 mm/d,秋冬季分别为2.53和2.76 mm/d。修正后的双作物系数模型估算春夏季温室黄瓜日ETc的决定系数(R2)、均方根误差(RMSE)和模型效率系数(Ens)分别为0.95、0.41 mm/d和0.93;估算秋冬季ETc的误差计算结果依次为0.91(R2)、0.48 mm/d(RMSE)和0.90(Ens)。修正后的双作物系数模型估算春夏季日平均Tr与实测值分别为2.37和2.19mm/d,秋冬季分别为1.43和1.34 mm/d。研究结果还显示,不同种植季节温室黄瓜全生育期日平均Tr占ETc的比例分别为64.62%(春夏季)和68.59%(秋冬季)。该研究成果不仅为制定准确的温室黄瓜灌溉制度提供了理论依据,而且对实现温室环境智能化控制及减少温室内无效的土面蒸发具有重要意义。     

Stacking集成模型模拟膜下滴灌玉米逐日蒸散量和作物系数

为准确模拟膜下滴灌玉米逐日蒸散量和作物系数,该研究以4个经典机器学习模型：随机森林（Random Forest,RF）、支持向量机（Support Vector Machine,SVM）、BP神经网络（Back Propagation Neural Network,BP）和Adaboost集成学习模型（Adaboost,ADA）为基础,基于Stacking算法建立了集成学习模型（Linear Stacking Model,LSM）对膜下滴灌玉米逐日蒸散量和作物系数进行模拟。并将LSM的模拟精度与RF、SVM、BP和ADA模型的模拟精度相比较,结果表明：1）RF、SVM、BP和ADA模型模拟膜下滴灌玉米的逐日蒸散量和作物系数时的相对均方根误差均大于0.2;2）相比RF、SVM、BP和ADA模型,LSM模型提高了玉米逐日蒸散量和作物系数模拟精度。LSM模拟的膜下滴灌玉米的作物系数相比于FAO推荐值更接近实测值;3）日序数、平均温度、株高、叶面积指数和短波辐射5个特征对玉米膜下滴灌玉米日蒸散量和作物系数影响最高,基于这5个特征建立的LSM模型模拟膜下滴灌玉米的蒸散量和作物系数的R2 分别为0.9和0.89,相对均方根误差分别为0.23和0.16。因此,建议在该研究区使用日序数、平均温度、株高、叶面积指数和短波辐射5个特征参数建立LSM模型模拟膜下滴灌玉米蒸散量和作物系数。该研究可为高效节水条件下作物蒸散量和作物系数的精准模拟和合理制定灌溉制度提供参考。     

Determination of the potential evapotranspiration and crop coefficient for saffron using a water-balance lysimeter

Agriculture is the major consumer of water and it is possible to decrease water consumption in this sector by proper irrigation scheduling. Irrigation scheduling is based on crop water requirements. Saffron is an important crop in Iran. The main purpose of this study was to determine the potential evapotranspiration and crop coefficient for saffron using single and dual crop coefficients, in Badjgah region, College of Agriculture, Shiraz University, Shiraz, Iran. Three water-balance lysimeters were used for this experiment in a two-year study. Total saffron potential evapotranspiration values were 523 and 640 mm in the first and second growing seasons, respectively. The maximum evapotranspiration rates for saffron were 4.5 and 6.1 mm d^?1 in the first and second growing seasons, respectively. Based on the results of this study, different saffron growing stages for evapotranspiration were 30, 40, 70 and 60 days. Crop coefficient (K _c) values for the initial, mid- and late-season growth stages were 0.41–0.45, 0.93–1.05 and 0.29–0.31 in both years, respectively. Basal crop coefficient (K _cb) values for the initial, mid- and late-season growth stages were 0.15–0.16, 0.41–0.65 and 0.15–0.17 in both years, respectively.     

通径分析结合BP神经网络方法估算夏玉米作物系数及蒸散量

准确估算蒸散量对于精准管理农田水分至关重要。为了解作物系数的动态特征,准确估算作物需水量,使用叶面积指数和气象要素模拟玉米全生育期作物系数及蒸散量。利用2018年五道沟实验站气象和称重式蒸渗仪实测数据,运用通径分析法筛选影响作物系数的关键因子,建立无雨期不同地下水埋深下作物系数模型,以此估算蒸散量。结果表明:1 m埋深下全生育期作物系数平均绝对误差为0.04 mm/d,相关系数为0.94,其中初期、发育期、中期和后期平均绝对误差分别为0.06、0.09、0.05和0.03 mm/d。3 m埋深下全生育期作物系数平均绝对误差为0.08 mm/d,相关系数为0.92,各生育期平均绝对误差分别为0.11、0.10、0.07和0.03 mm/d,利用温度、风速和叶面积指数模拟作物系数精度较高。1 m埋深全生育期ET平均绝对误差为0.72 mm/d,各生育阶段平均绝对误差分别为0.56、059、0.66和0.45 mm/d。3 m埋深全生育期ET平均绝对误差为0.73mm/d,各生育阶段ET平均绝对误差分别为0.82、0.98、0.68和0.29mm/d。不同时间尺度下(1、3、5 d) 2种埋...     

基于作物及遥感同化模型的小麦产量估测

为提高陕西省关中平原冬小麦的估产精度,该文通过粒子滤波算法同化Landsat遥感数据反演的状态量叶面积指数(leaf area index,LAI)、土壤含水量(0~20 cm)、地上干生物量数据和CERES-Wheat模型模拟的状态量数据,分析小麦不同生育期的LAI、土壤含水量及生物量同化值和实测单产的线性相关性,以构建同化估产模型。结果表明,在返青期土壤含水量同化值和实测单产的相关性高于LAI、生物量同化值和实测单产的相关性,选择土壤含水量作为最优变量;在拔节期和抽穗-灌浆期同时选择LAI、土壤含水量及生物量作为最优变量;在乳熟期选择生物量作为最优变量。在小麦各生育时期同化最优变量的估产精度(R2=0.85)高于同时同化LAI、土壤含水量及生物量的估产精度,同时同化LAI、土壤含水量及生物量的估产精度高于同时同化LAI和土壤含水量(或LAI和地上干生物量、或土壤含水量和地上干生物量)的估产精度,表明在作物不同生育时期同化与产量相关性较大的变量对提高估产精度有重要作用。     

基于双作物系数法的干旱区覆膜农田耗水及水量平衡分析

农田覆膜技术应用广泛,覆膜条件下农田蒸散发(ET)规律是制定合理灌溉制度、提高用水效率的基础。根据2014—2015年甘肃省石羊河流域春小麦试验观测资料率定和验证农田水量平衡模型,利用双作物系数法得到作物的耗水规律和耗水结构。结果表明,覆膜春小麦全生育期耗水比不覆膜减少10%~16%,有一定的节水效果。覆膜促进了春小麦全生育期蒸腾,蒸腾占总耗水的比例在70%~74%之间,比不覆膜情况提高了25%~27%。在春小麦生长前期,覆膜能够显著降低ET;中期,覆膜能够降低土壤蒸发、促进作物蒸腾。此外,覆膜还具有促进作物前期生长、延长作物中期生长、延缓冠层衰老的作用。     

Effects of biochar and fertilizer management on sunflower (Helianthus annuus L.) feedstock and soil properties

The need for bioenergy is increasing with increase in global energy demand, and sustainable soil and fertilizer management practices for bioenergy feedstock production are gaining importance. In this greenhouse study, we evaluated the effects of biochar and fertilizer nitrogen on soil and energy crop sunflower (Helianthus annuus L. var. Giganteus). Sunflower plants were treated with three rates of biochar, control (0 Mg ha^?1), low (25 Mg ha^?1) and high (50 Mg ha^?1), and three rates of fertilizers, 0% (control), 50% (low) and 100% (high) of the recommended nitrogen dose. Plant height, quality (chlorophyll content), biomass yield, feedstock energy, ash content and tissue nutrients were measured along with soil moisture and pH. Results showed an 11% increase in mean plant height under low biochar compared to control biochar-treated plants. High nitrogen treatment produced 26% and 18% more stalk and total above-ground plant (whole plant) biomass, respectively, compared to the control nitrogen treatment. High biochar treatment resulted in higher soil moisture holding, but lower soil pH than the control biochar treatment. Plant quality, energy and ash contents were not affected by either biochar or nitrogen. The plant tissue analysis provides a complete tissue macro- and micronutrient information on sunflower cultivar Giganteus, which was not done previously.     

Maize (Zea mays L.) yield and soil properties as affected by no tillage in the black soils of China

A four-year tillage experiment on maize was conducted in the high latitude region of Northeast of China. The main objective of this study was to investigate the effects of different field tillage practices on maize grain yield, soil physical properties, and soil water and temperature dynamics in Northeast of China. The tillage practices included moldboard plow tillage (MOT), rotary tillage (ROT), reduced tillage (RET), combined tillage (COT), and no tillage (NOT). The surface soil water content at depths of 0–20 cm was higher under NOT compared with other tillage practices, but not different at the deeper soil depths in 2011. The soil temperatures under NOT and RET were lower than those under moldboard plow tillage and ROT at depths of 5 and 15 cm, respectively, measured at 9:00 am in 2005. From the hourly dynamics of soil temperature, the differences among the tillage practices mainly appeared during the daytime (from 8:00 am to 7:00 pm). Among all the practices, the average daily soil temperature under ROT was the highest, while that under NOT was the lowest. MOT, ROT, and RET had higher soil accumulative infiltration compared with NOT and COT. The surface soil bulk density under NOT was higher than or equal to that under the other four tillage practices. The maize yields under NOT were the lowest among all the tillage practices for three years straight. Meanwhile, the yields under MOT were the highest, which were about 47%, 61%, and 38% higher than those under NOT. NOT practice is not recommended for use in spring-planted maize under the high latitude humid cool climate Mollisol region in Northeast of China.     

宁南旱区有机培肥对土壤水分和作物生产力影响的研究

通过对宁南旱区连续两年的有机肥定位试验,研究了不同肥力梯度下有机培肥对土壤水分及作物生产力的影响。结果表明,施肥量为高、中、低处理下,第1年种胡麻,成熟期的贮水量在0—100 cm土层分别比对照处理高13%、10%和0.9%,胡麻产量分别比对照处理高11%、10%和5%,土壤水分利用效率分别比对照处理高30%、29%和11%;在第2年种冬小麦,成熟期的贮水量在0—100 cm土层分别比对照处理高16%、14%和7%,冬小麦产量比对照处理高18%、25%、和13%,土壤水分利用效率分别比对照处理高14%、15%和6%。2年结果看出,施用有机肥可提高土壤含水量,利于土壤的扩蓄增容,且对提高作物产量和土壤水分利用效率有显著效果。     

Critical limit of boron for maize (Zea mays L.) in red and lateritic soil of Jharkhand,India

ABSTRACT

To establish a critical limit in soils and plant, an experiment was conducted in red and lateritic soil (Alfisols) of farmer’s field in tribal-dominated Panchayat Kurum, Palkot block, Gumla district, Jharkhand, India. Based on the results of the field experiment, the critical limits were determined as 0.48, 0.50, 0.47, and 0.42 mg kg^?1 in the soil, respectively, for hot water, hot calcium chloride, salicylic acid, and ammonium acetate-extractable B, while a critical limit of 12.00 mg kg^?1 was observed in maize tissue using the graphical method. In an analysis of variance method, the critical limits of B in soils were found as 0.45, 0.54, 0.49, and 0.43 mg kg^?1 using hot water, hot calcium chloride, salicylic acid, and ammonium acetate extractants, respectively. Maize plants were highly responsive to B application where soil B level was below the critical limit (0.50 mg kg^?1). In a field experiment, grain yield of maize increased with increasing levels of B application, while soil application at 1.0 kg ha^?1 + two foliar application (at the knee and pre-flowering stages) of borax at 0.2% were showed significantly higher grain yield of the maize crop. The hot water, hot calcium chloride, salicylic acid, and ammonium acetate-extractable B were significantly and positively correlated with organic carbon and negatively correlated with the electrical conductivity of soils.     

Effect of drip irrigation and mulches on physiological parameters,soil temperature,picking patterns and yield in capsicum (Capsicum annuum L.)

Water and temperature are critical for producing vegetable crops, especially during winter, when the availability of water is meager and temperature falls. Studies of drip irrigation and mulch were undertaken to find the effect on different growth and yield parameters in pepper (Capsicum annuum L.). The experiment was laid out in a split-plot design with four main and four subplots. Irrigation levels were placed on main plots and mulches on subplots with three replicates for each. All recorded vegetative parameters were higher with drip irrigation at 1.0 pan evaporation (Epan) and black polythene mulch. Physiological parameters such as photosynthesis rate (18.01 and 17.45 μmol m^?2 s^?1), transpiration rate (6.19 and 5.86 mmol H₂O m^?2 s^?1) and chlorophyll content (27.34 and 28.39; 39.22 and 41.27 SPAD, respectively at 50 and 100 days after planting) were maximal in crops with drip irrigation at 1.0 Epan and mulched with black polythene. Soil and canopy temperature were significantly higher on flood irrigation at 1.0 Epan. Soil temperature was higher with the black polythene mulch, but canopy temperature was higher with no mulch. A higher level of drip irrigation and black polythene mulch result in early picking with higher yields compared with flood irrigation and no mulch.     

Determination of actual evapotranspiration and crop coefficients of broad bean (Vicia Faba L.) grown under field conditions in the jordan valley,jordan: Bestimmung der aktuellen evapotranspiration und pflanzenbestandskoeffizienten von bohnen (Vicia Faba L.) unter feldbedingungen im jordantal,jordanien

This study was conducted to determine actual evapotranspiration and crop coefficients at different growth stages of broad bean (Vicia faba L.) grown in an open field in the Jordan Valley, Jordan using a precise and accurate approach. The study involved 30-min fluxes measurements of energy budget components over broad bean crop using a complete setup of an Eddy Correlation (EC) system. The measurements were conducted during the three main crop growth stages namely initial, development, and midseason growth stages following the Food and Agriculture Organization of the United Nations (FAO) crop coefficient model for green harvested broad bean crop. The average crop coefficients during the initial (K_{C ini}), development (K_{C dev}) and midseason (K_{C mid}) growth stages were 0.37, 0.8 and 1.05, respectively. The measured weighted average crop coefficient over the entire growing season K_{C GS} was 9.5% lower than the FAO corresponding value.

Results showed that there was a clear decrease of (bulk) surface resistance (r_s) as crop canopy developed. Daily average r_s values were 855, 337, and 166?s/m for initial, development, and midseason growth stages, respectively. Moreover, r_s was found to be highly correlated to crop height (h_c). A simple linear relation between r_s and h_c with R² of 0.91 was found. This relation will enable future direct determination of crop evapotranspiration (ET_C) using Penman-Monteith equation without the need to calculate both grass reference evapotranspiration (ET_O) and crop coefficient (K_C) values.     

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.     

Residual nitrogen effects on a succeeding oat (Avena sativa L.) Crop of clover species and ryegrass (Lolium perenne L.) undersown in winter wheat (Triticum aestivum L.)

The aim of the present investigation was to study the effect of white clover (var. Milka and Donna), red clover (var. Fanny) and ryegrass (var. Tove) undersown in winter wheat on a succeeding oat crop. Under the climatic conditions prevailing in Sweden, growing a catch crop after winter cereals is of particular interest because the latter are usually followed by a spring sown crop, leaving the ground bare during autumn and winter. Field trials were carried out during three growing seasons in an integrated farming system and for one year in an organic farming system. Competition from the dense wheat crop in the integrated farming system had a negative effect on the undersown species, and at harvest of the wheat they showed quite poor growth in all three years, with nitrogen contents under 5 kg ha^?1. No significant yield increase was measured without added nitrogen when the averages for all three years were calculated. On average, the grain yields were improved by 750 kg ha^?1 (14% moisture content) for the treatments with undersown clover for all three years when 90 kg N ha^?1 were added. The experiment within the organic system showed a different pattern with a better development of the undersown clover species, with nitrogen contents approximately 25 kg ha^?1 and an improvement in oat grain yield, from around 2?000 kg ha^?1 for the control to almost 3?500 kg ha^?1 with clover undersown the previous year.     

Impact of land degradation on soil respiration in a steppe (Stipa tenacissima L.) semi-arid ecosystem in the SE of Spain

Climate change scenarios predict increases in temperature, changes in precipitation patterns, and longer drought periods in most semi-arid regions of the world. Ecosystems in these regions are prone to land degradation, which may be aggravated by climate change. Soil respiration is one of the main processes responsible for organic carbon losses from arid and semi-arid ecosystems. We measured soil respiration over one year in two steppe ecosystems having different degrees of land degradation under three ground-covers: with vegetation, bare soil, and an intermediate situation between plants and bare soil.The largest differences in soil respiration rates between the sites were observed in spring, coinciding with the highest level of plant activity. The degraded site had drier and hotter soils with less soil water availability and a longer drought period. As a result, vegetation on the degraded site did not respond to spring rainfall events. Soil respiration showed a strong seasonal variability, with average annual rates of 1.1 and 0.8 μmol CO₂ m⁻² s⁻¹ in the natural and degraded sites, respectively. We did not observe significant differences in soil respiration rates associated with ground-cover i.e., the temporal variation was much larger than the spatial variation. At both sites, soil moisture was the controlling driver of soil respiration for most of the year, when temperatures were above 20 °C and constrained the response to temperature for the few months when the temperature was below 20 °C. An empirical model based on soil temperature and soil moisture explained 90% and 72% of the seasonal variability of soil respiration on the natural and degraded sites, respectively. For the first time, this study suggests that land degradation may alter the carbon balance of these ecosystems through changes in the temporal dynamics of soil respiration and plant productivity, which have important negative consequences for ecosystem functioning and sustainability.     

Impact of nodule damage by Rivellia angulata on N2-fixation,growth, and yield of pigeonpea (Cajanus cajan L. Millsp.) grown in a Vertisol

Summary Damage caused by Rivellia angulata larvae to pigeonpea root nodules at the ICRISAT center in India was greater in the crop grown on Vertisols (up to 86%) compared to that on Alfisols (20%). Attempts to quantify the field effects of nodule damage on growth and yield of pigeonpea in a Vertisol, involving many heavy applications of soil insecticides (aldrin and hexachlorocyclohexane) failed because the insecticides did not control the pest and adversely affected the growth of the pigeonpea and the subsequent crop of sorghum (Sorgorum bicolor L. Moench). The impact of nodule damage on pigeonpea growth, yield and nutrient uptake was successfully studied in greenhouse-grown plants at three N levels. In this pot study, artificial inoculation with Rivellia sp. led to substantial nodule damage (70%). The results of this damage were a significant overall reduction in nodule dry weight (46%), acetylene reduction activity (31%), total leaf area (36%), chlorophyll content of leaves (39%) and shoot dry weight (23%) 68 days after sowing. At maturity, Rivellia sp. infestation caused significant reductions in top dry weight (22%), root and nodule dry weight (27%), seed dry weight (14%), and total N (29%) and P uptake (19%). The problems and prospects of manipulating nodule damage so as to reduce N losses in pigeonpea are discussed.Submitted as JA No. 756 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)     

Diversification of rice (Oryza sativa L.)-based cropping systems for higher productivity,resource-use efficiency and economic returns in south Gujarat,India

The continuous growing of rice has led to a deterioration in soil quality, resulting in a serious threat to agricultural sustainability in the high rainfall zone of south Gujarat, India. Therefore, crop diversification with a wider choice in the production of crop varieties is being promoted to restore the soil quality. A field experiment was conducted in Navsari, India during 2003–2007 on a Vertisol to evaluate the productivity, sustainability, resource-use efficiency and economics of 10 rice-based cropping systems. The results showed that system productivity for rice–fenugreek (Trigonella foenum-graecum)–okra (Abelmoschus esculentus) was highest (25.73 t ha^?1), followed by rice–onion (Allium cepa)–cowpea (Vigna sinensis L.) (24.15 t ha^?1); and the lowest system productivity was observed with the rice–wheat (Triticum aestivum)–fallow system (7.85 t ha^?1). The sustainable yield index (0.97), production efficiency (102.94 kg ha^?1 day^?1) and field water use efficiency (15.98 kg ha^?1 mm^?1) were maximum with the rice–fenugreek–okra system. Similarly, net return (96,286 Rs ha^?1), net return per rupee invested (2.83 Rs), monetary production efficiency (385.14 Rs ha^?1 day^?1) and water use efficiency (59.80 Rs ha^?1 mm^?1) were maximum with the rice–fenugreek–okra cropping sequence. There were significant effects of various cropping sequences on available nitrogen, phosphorus, potassium and organic carbon content in the soil. Overall, the rice–fenugreek–okra system was found to be the most productive, sustainable, resource-use efficient and remunerative cropping system, followed by the rice–onion–cowpea system.     

Biochar and inorganic nitrogen fertilizer effects on maize (Zea mays L.) nitrogen use and yield in moist semi-deciduous forest zone of Ghana

Abstract

Maize (Zea mays L.) is a major nitrogen consuming crop, as nitrogen is considered as an important determinant of its grain yield. Though inorganic fertilizer is widely recommended, the problem of high cost and inaccessibility limit its usage by resource poor farmers. Biochar application provides a new technology for both soil fertility and crop productivity improvement. With limited research on the suitability of biochar for soil improvement practices in Ghana, our objective was to determine the synergistic effect of biochar and inorganic fertilizer on the nitrogen uptake, nitrogen use efficiency, and yield of maize. Field experiment was conducted in Ghana, KNUST, in the major and minor raining seasons. Biochar was applied at 0, 5, 10, 15, and 20 t ha^?1 and fertilizer N applied at 0, 45, and 90?kg ha^?1. The results showed significantly (p??1 supplemented with 45?kg N ha^?1 increased N uptake by 200%, and grain yield by 213% and 160% relative to the control in the minor and major rainy seasons, respectively. The greater yield of maize recorded on biochar-amended soils was attributed to the improved N uptake and nitrogen use efficiency. In conclusion, our finding suggests that the application of combined biochar and inorganic N fertilizer is not only ecologically prudent, but economically viable and a practicable alternative to current farmers’ practice of cultivating maize in Ghana.     

太行山山前平原冬小麦和夏玉米灌溉指标研究

根据1998～2001年的田间试验,研究了太行山山前平原高产农区主要作物冬小麦和夏玉米耗水量与产量和水分利用效率的关系,确定了这两种作物不同生育期水分敏感指数和允许的土壤水分下限指标和有限供水条件下的优化供水制度。并通过对叶片水势和冠气温差的测定,建立了这两种指标与作物水分亏缺程度的关系,形成指导农田灌溉的土壤指标、冠气温差指标和叶片水势指标体系