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1.
Sustainable potassium (K) management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale.We analyzed responses of grain yield of wheat (Triticum aestivum L.) and maize (Zea mays L.),K efficiency,and partial balance (difference between K input through fertilizer and K output in the aboveground biomass) during 15-(1990-2005) or 18-year (1990-2008) K fertilizations at five distinctive agroecological zones across China.Compared to the inorganic nitrogen (N) and phosphorus (P) fertilization,the inorganic NPK fertilization significantly increased grain yields of wheat (21%) and maize (16%-72%) at Qiyang and Changping,where soils have low exchangeable and non-exchangeable K contents,but not at rmqi,Yangling and Zhengzhou,where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants.Compared to the inorganic NPK fertilization,the inorganic NPK (30% N) and organic manure (70% N) fertilization (NPKM) increased grain yields of wheat (14%-40%) and maize (9%-61%) at four sites,but not at Zhengzhou.For a productivity of wheat at 2-5 t ha-1 or maize at 3-6 t ha-1,13-26 or 9-17 kg K ha-1 were required to produce 1.0 t wheat or maize.The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha-1 year-1 less than the NPK fertilization,which accumulated 28 kg ha-1 year-1 less K than the NPKM fertilization.A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM fertilization is urgently needed to increase both crop yield and K use efficiency at different agroecological zones across China.  相似文献   

2.
长期稻田垄作免耕对土壤性质和水稻产量的影响   总被引：4，自引：0，他引：4  
A tillage method of combining ridge with no-tillage (RNT) was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern, soil water stable aggregate distribution, nutrients stratification and yields of rice and post-rice crops. After flooded paddy field (FPF) was practiced with RNT for a long time, soil profile changed from G to A-P-G, and horizon G was shifted to a deeper position in the profile. Also the proportion of macroaggregate (> 2 mm) increased, whereas the proportion of silt and clay (< 0.053 mm) decreased under RNT, indicating a better soil structure that will prevent erosion. RNT helped to control leaching and significantly improved total N, P, K and organic matter in soil. The highest crop yields were found under RNT system every year, and total crop yields were higher under conventional paddy-upland rotation tillage (CR) than under FPF, except in 2003 and 2006 when serious drought occurred. RNT was proven to be a better tillage method for lowland rice-based cropping system.  相似文献   

3.
提高高产玉米氮素利用效率的根层氮素管理技术   总被引：5，自引：0，他引：5  
Many recently developed N management strategies have been extremely successful in improving N use efficiency.How-ever,attempts to further increase grain yields have had limited success.Field experiments were conducted in 2007 and 2008 at four sites to evaluate the effect of an in-season root-zone N management strategy on maize (Zea mays L.).According to the in-season root-zone N management,the optimal N rate (ONR) was determined by subtracting measured soil mineral N (NH + 4--N and NO 3--N) in the root zone from N target values.Other treatments included a control without N fertilization,70% of ONR,130% of ONR,and recommended N rate (RNR) by agronomists in China that have been shown to approach maize yield potentials.Although apparent N recovery for the ONR treatment was significantly higher than that under RNR in 2007,grain yield declined from 13.3 to 11.0 Mg ha 1 because of an underestimation of N uptake.In 2008,N target values were adjusted to match crop uptake,and N fertilization rates were reduced from 450 kg N ha-1 for RNR to 225 to 265 kg N ha-1 for ONR.High maize yields were maintained at 12.6 to 13.5 Mg ha 1,which were twice the yield from typical farmers’ practice.As a result,apparent N recovery increased from 29% to 66%,and estimated N losses decreased significantly for the ONR treatment compared to the RNR treatment.In conclusion,the in-season root-zone N management approach was able to achieve high yields,high NUE and low N losses.  相似文献   

4.
Maize （Zea mays L.）, a staple crop grown from June to September during the rainy season on the North China Plain, is usually inter-planted in winter wheat （Triticum aestivum L.） fields about one week before harvesting of the winter wheat. In order to improve irrigation efficiency in this region of serious water shortage, field studies in 1999 and 2001, two dry seasons with less than average seasonal rainfall, were conducted with up to five irrigation applications to determine evapotranspiration, calculate the crop coefficient, and optimize the irrigation schedule with maize under mulch, as well as to establish the effects of irrigation timing and the number of applications on grain yield and water use efficiency （WUE） of maize. Results showed that with grain production at about 8 000 kg ha^-1 the total evapotranspiration and WUE of irrigated maize under mulch were about 380-400 mm and 2.0-2.2 kg m^-3, respectively. Also in 2001 WUE of maize with mulch for the treatment with three irrigations was 11.8% better than that without mulch. In the 1999 and 2001 seasons, maize yield significantly improved （P = 0.05） with four irrigation applications, however, further increases were not significant. At the same time there were no significant differences for WUE with two to four irrigation applications. In the 2001 season mulch lead to a decrease of 50 mm in the total soil evaporation, and the maize crop coefficient under mulch varied between 0.3-1.3 with a seasonal average of 1.0.  相似文献   

5.
AMANULLAH  M. W. KHAN 《土壤圈》2011,21(4):532-538
A field experiment was conducted using a split plot randomized complete block design with three replications to study the effects of potassium (K) and phosphorus (P) application on sunflower (Helianthus annuus L.) growth at the New Developmental Research Farm of Khyber Pakhtunkhwa Agricultural University in Peshawar,Pakistan.Six levels of K (0,25,50,75,100 and 125 kg K ha-1) were main plots while four levels of P (0,45,90 and 135 kg P ha-1) were subplots.Increase in both K and P levels enhanced grain oil concentration of sunflower.Increase in P level increased grain protein concentration,while increase in K level decreased grain protein concentration.Both oil and protein yields increased significantly with increase in K and P levels.The increase in oil and protein yields of sunflower was mainly attributed to the improvement in yield components (grains per head,grain weight and head size) and the significant increase in grain yield.The highest net returns of 297 and 368 US$ ha-1 based on grain and oil yields,respectively,were obtained from a combination of 100 kg K ha-1 + 45 kg P ha-1.  相似文献   

6.
海河流域合理生态用水比例的确定   总被引：9，自引：0，他引：9  
Winter wheat-maize rotations are dominant cropping systems on the North China Plain, where recently the use of organic manure with grain crops has almost disappeared. This could reduce soil fertility and crop productivity in the long run. A 20-year field experiment was conducted to 1） assess the effect of inorganic and organic nutrient sources on yield and yield trends of both winter wheat and maize, 2） monitor the changes in soil organic matter content under continuous wheat-maize cropping with different soil fertility management schemes, and 3） identify reasons for yield trends observed in Xuzhou City, Jiangsu Province, over a 20-year period. There were eight treatments applied to both wheat and maize seasons： a control treatment （C）; three inorganic fertilizers, that is, nitrogen （N）, nitrogen and phosphorus （NP）, and nitrogen, phosphorus and potassium （NPK）; and addition of farmyard manure （FYM） to these four treatments, that is, M, MN, MNP, and MNPK. At the end of the experiment the MN, MNP, and MNPK treatments had the highest yields, about 7 t wheat ha^-1 and 7.5 t maize ha^-1, with each about 1 t ha^-1 more than the NPK treatments. Over 20 years with FYM soil organic matter increased by 80% compared to only 10% with NPK, which explained yield increases. However, from an environmental and agronomic perspective, manure application was not a superior strategy to NPK fertilizers. If manure was to be applied, though, it would be best applied to the wheat crop, which showed a better response than maize.  相似文献   

7.
Conservation agriculture(CA)-based best-bet crop management practices may increase crop and water productivity, while conserving and sustaining natural resources. We evaluated the performance of rainy season maize during 2014 under an ongoing long-term trial(established in 2008) with three tillage practices, i.e., permanent bed(PB), zero tillage(ZT), and conventional tillage(CT) as main plots, and four intensified maize-based cropping systems, i.e., maize-wheat-mungbean, maize-chickpea-Sesbania(MCS), maizemustard-mungbean, and maize-maize-Sesbania) as subplot treatments. In the seventh rainy season of the experiment, maize growth parameters, yield attributes, yield, and water-and energy-use efficiency were highest at fixed plots under ZT. Maize growth parameters were significantly(P 0.05) superior under ZT and PB compared with CT. Maize yield attributes, including cobs per m~2(7.8), cob length(0.183 m), grain rows per cob(13.8), and grains per row(35.6), were significantly higher under ZT than CT; however, no significant effect of cropping systems was found on maize growth and yield attributes. Zero tillage exhibited the highest maize productivity(4 589 kg ha~(-1)). However, among the cropping systems, MCS exhibited the highest maize productivity(4 582 kg ha~(-1)). In maize, water use was reduced by 80.2–120.9 mm ha-1under ZT and PB compared with CT, which ultimately enhanced the economic water-use efficiency by 42.0% and 36.6%, respectively. The ZT and PB showed a 3.5%–31.8% increase in soil organic carbon(SOC) at different soil depths(0–0.45 m), and a 32.3%–39.9% increase in energy productivity compared with CT. Overall, our results showed that CA-based ZT and PB practices coupled with diversified maize-based cropping systems effectively enhanced maize yield and SOC,as well as water-and energy-use efficiency, in northwestern India.  相似文献   

8.
The greatest challenge for tropical agriculture is land degradation and reduction in soil fertility for sustainable crop and livestock production.Associated problems include soil erosion,nutrient mining,competition for biomass for multiple uses,limited application of inorganic fertilizers,and limited capacity of farmers to recognize the decline in soil quality and its consequences on productivity.Integrated soil fertility management(ISFM) is an approach to improve crop yields,while preserving sustainable and long-term soil fertility through the combined judicious use of fertilizers,recycled organic resources,responsive crop varieties,and improved agronomic practices,which minimize nutrient losses and improve the nutrient-use efficiency of crops.Soil fertility and nutrient management studies in Ethiopia under on-station and on-farm conditions showed that the combined application of inorganic and organic fertilizers significantly increased crop yields compared to either alone in tropical agro-ecosystems.Yield benefits were more apparent when fertilizer application was accompanied by crop rotation,green manuring,or crop residue management.The combination of manure and NP fertilizer could increase wheat and faba bean grain yields by 50%–100%,whereas crop rotation with grain legumes could increase cereal grain yields by up to 200%.Although organic residues are key inputs for soil fertility management,about 85% of these residues is used for livestock feed and energy;thus,there is a need for increasing crop biomass.The main incentive for farmers to adopt ISFM practices is economic benefits.The success of ISFM also depends on research and development institutions to provide technical support,technology adoption,information dissemination,and creation of market incentives for farmers in tropical agro-ecosystems.  相似文献   

9.
P. A. NDAKIDEMI 《土壤圈》2007,17(6):732-738
On-farm experiments were conducted in farmers＇ fields at 6 different sites in Western Usambara Mountains （WUM） in northern Tanzania during the 2000-2001 cropping season. The objectives were to study the effects of Tughutu （ Vernonia subligera O. Hoffn） pruning in combination with Minjingu phosphate rock （MPR） or triple super phosphate （TSP） supply on the concentration of P in the tissues and seed yields of common bean, and to assess the economic returns of these different technologies to farmers. The experimental design was a randomized complete block with each of the 6 farmers＇ fields used as a replicate. The treatments included： control, MPR or TSP each at 26 kg P ha^-1, Tughutu at 2.5 t ha^-1, and Tughutu at 2.5 t ha^-1 combined with MPR or TSP at 26 kg P ha^-1. Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g^-1 to 1.70 and 1.95 mg g^-1 respectively. Combining MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g^-1. The relative agronomic effectiveness （RAE） of MPR ranged from 12.5% to 45.0%. Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone, and 148%-219% from Tughutu application combined with 26 kg P ha^-1 of MPR or TSP relative to the control. With Tughutu alone, seed yield increased by 53%. From economic analysis, the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly （P ≤ 0.001） higher marginal rate of return and dollar profit for common bean farmers in WUM in northern Tanzania. It is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in Tanzania.  相似文献   

10.
翻耕和覆盖对我国黄土区麦田土壤水分的影响   总被引：13，自引：0，他引：13  
Effects of different methods of tillage and mulch on soil moisture at fallow stage were studied in rainy and rain-deficient years.Soil moisture content per 20 cm was measured vertically within 0-300 cm soil layers in an experiment with five treatments:deep-loosening tillage(DLT),traditional tillage(TT),plastic mulch(PM),straw mulch(SM) and plastic plus straw mulch(PSM),All mulch treatments were under no tillage conditions.Total storage of precipitation in soil from 0 to 300cm was determined before sowing,Results showed that the new methods of tillage and mulch were the basic ways to improve water condition in dryland wheat fields.In a rainy year,PM with no tillage played a significant role in storing and conserving precipitation.while in a rain-deficient year,the role was not significant,Due to evaporation.DLT did not promote the storage of soil moisture,SM was the best way to store and conserve soil moisture,In SM treatment the wheat yields increased by more than 20%.  相似文献   

11.
ABSTRACT

A study was conducted from 2014 to 2017 in Malawi to elucidate the short-term effects of maize-legume intercropping and rotation systems under conservation agriculture (CA) and conventional tillage (CT) on crop productivity and profitability. Twelve farmers hosted on-farm trials per district, in three districts, with each farmer having six plots. The design of the study was randomised complete block design arranged in a split plot fashion with tillage as main plot and cropping systems as sub-plots, with each farmer acting as a replicate. CA had 1400 and 3200 kg ha?1 more maize grain yield in the second and third seasons, respectively compared with CT. In the first two seasons, CT had 310, 180 and 270 kg ha?1 more cowpea, soybean and pigeon pea grain yields in Salima, Mzimba and Mangochi districts, respectively, compared with CA. Similarly, CA had 1100 and 950 kg ha?1 more groundnut grain yields than CT in Salima and Mzimba districts in the second and third seasons, respectively. Over the three-year study period, partial land equivalent ratio for maize ranged from 0.78 to 1.24. Largest net returns were achieved by intercropping maize with pigeon pea in Mangochi and rotating maize and groundnut in Mzimba and Salima districts.  相似文献   

12.
Continuous mono-cropping of rice-wheat (RW) system with conventional tillage (CT) based management practices have led to decline in soil health, groundwater table and farmers profit in north-west India. A medium-term (4 years) farmer’s participatory strategic research trial of basmati RW system was conducted to evaluate the effects of conservation agriculture (CA) based management practices on crop yields, water productivity, profitability and soil quality. Six treatments were compared varied in the cropping system, tillage, crop establishment and residue management. CA-based management under zero-till direct seeded rice-wheat-mungbean recorded 36% higher system yield than conventional till rice-wheat system (14.91 Mg ha?1). CA-based rice-wheat system and rice-wheat-mungbean system saved ~35% irrigation water compared to conventional RW system (2168 mm ha?1). Total water productivity (WPI+R) was improved by 67% with CA-based rice-wheat-mungbean system (0.90 kg grain m?3) over the conventional system. On system basis, 42% higher net return was recorded with CA-based rice-wheat-mungbean system compared to conventional system (USD 2570 ha?1). Mungbean integration in basmati RW system contributed 29% share in system net returns across the treatments. Soil chemical and biological properties were improved by ~40% and 150%, respectively, with CA-based management system.  相似文献   

13.
The objective was to evaluate the effect of different agricultural managements on soil organic C (SOC) storage and crop yields in the North China Plain (NCP). The study was conducted at five experimental stations. Different agricultural managements were designed, including optimal (OPT) and conventional (CON) irrigation and fertilization treatments, different amounts of fertilization application and residue‐return treatments, and different tillage practices. Compared to the CON treatment, SOC storage in the 1 m soil profile under the OPT treatment increased by 2 t ha–1, 8 t ha–1, and 4 t ha–1 at Quzhou, Wuqiao, and Dongbeiwang sites, respectively. The annual increasing rate of SOC storages in the topsoil (0–30 cm) under the OPT treatments at Wuqiao (0.88 t ha–1 y–1), Quzhou (0.93 t ha–1 y–1), and Dongbeiwang (1.86 t ha–1 y–1) were higher than those in the CON treatments at Wuqiao (0.15 t ha–1 y–1), Quzhou (0.54 t ha–1 y–1), and Dongbeiwang (0.28 t ha–1 y–1), but the difference of grain yields between the two treatments was not significant. The SOC storage in 1 m soil profile in the no‐tillage treatment with standing residue return (NT1) at Luancheng increased by 5 t ha–1 and 7 t ha–1 compared with rotary‐tillage (RT) and conventional‐tillage (CT) treatments, respectively, but the crop yield under no‐tillage treatment was the lowest. While at Quzhou site, it increased by 3 t ha–1 in the top 40 cm soil under the NT treatment compared to the CT treatment. The annual increasing rate of SOC storage in the top 30 cm under NT treatment was also the highest (1.08 t ha–1 y–1 at Luancheng, 1.86 t ha–1 y–1 at Quzhou), compared to the other tillage treatments. At Henghsui site, the combination of the highest fertilization application and highest residue‐return treatments got the highest SOC storage and the highest crop yields. We concluded that the agricultural management practices, such as optimal irrigation and fertilization treatment, the higher fertilization, residue return and RT, has significant impact on the SOC storage and agricultural sustainability in the NCP.  相似文献   

14.
About 80% of Ethiopia's population is involved in rain‐fed agriculture. Moisture stress coupled with traditional tillage with breaking ard plough, locally known as ‘Maresha ’ are the major limiting factors for agricultural production. Soil erosion, low infiltration and decline agricultural productivity because of conventional tillage implement have been frequently reported. In order to curve this situation and meet the huge food demand of the growing population, different conservation tillage systems have been implemented. However, there is limited information about the impacts of the practices. This review paper therefore aimed at providing adequate information concerning the impacts of the practices on water balance and crop yield. Systematic, best evidence and narrative review techniques were used. Results revealed that the application of conservation tillage had brought significant improvement on water balance and agricultural production. Researchers found over 50% decreased in surface runoff, 9 to 40% improvement in water productivity and good crop transpiration (T = 53 mm season−1), compared to conventional tillage T = 49 mm‐season−1 because of conservation tillage implement. Moreover, doubled grain yield was obtained from ridging, subsoiling and wing plough (1076, 1044 and 1040 kg ha−1, respectively) compared to traditional tillage which resulted in 540 kg ha−1. Improving water balance and agricultural production in rain‐fed agriculture need to reduce evaporation and surface runoff through improving moisture retention and transpiration. This could be achieved by the adoption of conservation tillage which can improve on‐farm water balance, yields and water productivity among smallholder farmers in Ethiopia. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

15.
Subsistence farmers in Africa depend largely on the soil organic matter to sustain crop productivity. Long-term changes in soil organic carbon and nitrogen were measured after woodland clearance for smallholder subsistence farming or for commercial farming. The contents of organic carbon and nitrogen in soil under reference woodlands were largest (53.3 t C ha−1, 4.88 t N ha−1) in a red clay soil (∼ 50% clay + silt), followed by a granitic sand (∼ 12% clay + silt; 22.8 t C ha−1, 1.47 t N ha−1) and least (19.5 t C ha−1, 0.88 t N ha−1) in a Kalahari sand (∼ 5% clay + silt). Organic carbon declined rapidly under cultivation to attain new equilibria within 10 years on all smallholdings. Greatest losses occurred in soils that initially contained most carbon and nitrogen in the order: red clay (22.4 t C ha−1 and 1.0 t N ha−1) > granitic sand (13.2 t C ha−1 and 0.8 t N ha−1) > Kalahari sand (10.6 t C ha−1 and 0.5 t N ha−1). On the clay soil, commercial farming with intensive use of mineral fertilizers and incorporation of maize stover led to more gradual decline: at equilibrium, contents of carbon and nitrogen were 15 t C ha−1 and 1.7 t N ha−1 greater than on smallholdings with similar soil and climate. In the Kalahari sand the δ13C of organic C remained constant after woodland clearance, and maize contributed less than 10% of the total C even after 55 years. The δ13C signature increased slightly with increasing duration of cultivation by smallholders in the granitic sands and red clay soil where maize contributed 29% and 35% of the C at equilibrium. Under more productive commercial farming, the carbon derived from maize accounted for 50% of the total after 10 years of cultivation and 67% at equilibrium. The persistence of woodland carbon in the sandy soil is attributed to chemical stabilization resulting from large concentrations of lignin and polyphenols in the tree litter, or as charcoal.  相似文献   

16.
Field runoff plots were established in 1984 to evaluate the effects of slope length on runoff, soil erosion and crop yields on newly cleared land for four consecutive years (1984–1987) on an Alfisol at Ibadan, Nigeria. The experimental treatments involved six slope lengths (60 m to 10 m at 10-m increments) and two tillage methods (plough-based conventional tillage and a herbicide-based no-till method) of seedbed preparation. A uniform crop rotation of maize (Zea mays)/cowpeas (Vigna unguiculata) was adopted for all four years. An uncropped and ploughed plot of 25 m length was used as a control. The water runoff from the conventional tillage treatment was not significantly affected by slope length, but runoff from the no-till treatment significantly increased with a decrease in slope length. The average runoff from the no-till treatment was 1·85 per cent of rainfall for 60 m, 2·25 per cent for 40 m, 2·95 per cent for 30 m, 4·7 per cent for 20 m and 5·15 per cent for 10 m slope length. In contrast to runoff, soil erosion in the conventional tillage treatment decreased significantly with a decrease in slope length. For conventional tillage, the average soil erosion was 9·59 Mg ha−1 for 60 m, 9·88 Mg ha−1 for 50 m, 6·84 Mg ha−1 for 40 m, 5·69 Mg ha−1 for 30 m, 1·27 Mg ha−1 for 20 m and 2·19 Mg ha−1 for 10 m slope length. Because the no-till method was extremely effective in reducing soil erosion, there were no definite trends in erosion with regard to slope length. The average sediment load (erosion:runoff ratio) also decreased with a decrease in slope length from 66·3 kg ha−1 mm−1 for 60 m to 36·3 kg ha−1 mm−1 for 10 m slope length. The mean C factor (ratio of soil erosion from cropped land to uncropped control) also decreased with a decrease in slope length. Similarly, the erosion:crop yield ratio decreased with a decrease in slope length, and the relative decrease was more drastic in conventional tillage than in the no-till treatment. The slope length (L) and erosion relationship fits a polynomial function (Y=c+aL+bL2). Formulae are proposed for computing the optimum terrace spacing in relation to slope gradient and tillage method. © 1997 John Wiley & Sons, Ltd.  相似文献   

17.
Abstract. After six years of bush‐fallow, residual effects on soil productivity of tillage practices prior to the fallow were investigated on an Alfisol in south western Nigeria. In 1996 fallow was followed by maize intercropped with cover crops of Pueraria phaseoloides, Mucuna pruriens or cowpea (Vigna unguiculata) and no intercrop. Parameters measured included soil properties, ground cover, crop growth and yield, rainfall erosivity, runoff and soil loss. In spite of six‐years of bush‐fallow and establishment of cover crops, soil erosion was significantly greater on plots that had been conventionally cultivated previously using disc ploughs, harrows and mechanical rotovators (1.78 t ha?1season?1) compared to previously no‐till plots (1.34 t ha?1season?1). Crop growth and yields were least and soil loss greatest (2.83 t ha?1season?1) on the previous bare plot. Maize grain yield was highest using Pueraria phaseoloides as an intercrop (2.15 t ha?1) followed by a cowpea intercrop (1.92 t ha?1), maize without intercrop (1.87 t ha?1) and Mucuna pruriens intercrop (1.71 t ha?1). The maize grain yields reflected levels of competition from the cover crops. Cowpea–maize intercrop may be most suitable for farmers because maize yields were satisfactory and cowpea grain serves as additional subsistence. Cowpea yields were 390 kg ha?1. Soil erosion was also moderate using cowpea as an intercrop (1.71 t ha?1season?1). However, Pueraria phaseoloides gave the best erosion control with a soil loss of 1.34 t ha?1season?1.  相似文献   

18.
A 2-year research experiment was laid out in a split-plot design with moldboard ploughing (MP, control) and minimum tillage (MT) as main plots and crop sequences as sub-plots. Summer-winter cropping sequences were fallow-wheat (Triticum aestivum L.) (FW, control), mungbean (Vigna radiata L.)-wheat (MW), sorghum (Sorghum bicolor L.)-wheat (SW), green manure-wheat (GW) and mungbean-chickpea (MC) (Cicer arietinum L.). During 2010–2011, in summer, mungbean crop produced the highest above ground biomass in mungbean-chickpea sequence under MP tillage (4.24 Mg ha–1 mungbean) and in mungbean-wheat sequence under MT tillage (4.11 Mg ha–1 mungbean). In winter, chickpea gave the highest biomass in mungbean-chickpea sequence under both tillage systems. During 2011–2012, mungbean produced the highest above ground biomass in mungbean-wheat sequence under MT tillage (4.43 Mg ha–1 mungbean) and in both the mungbean-chickpea and mungbean-wheat sequences under MP tillage (4.24 and 4.17 Mg ha–1 mungbean, respectively). In winter, fallow-wheat sequence gave the highest biomass in both tillage systems. The differences in grain yields were statistically non-significant in both the years. The gross marginal benefit ranged between ?190 and 548$ ha–1 in the first year and ?165 and 1124$ ha–1 in the second year. The net benefit values were the highest in mung-chickpea sequence under both tillage systems (1008 and 596$ ha–1 under MP and MT, respectively), which gave cost–benefit ratios of 5.45 and 3.68, respectively. Use of legume-based cropping sequences is a sustainable and cost-effective practice in drylands of northern Punjab, Pakistan.  相似文献   

19.
Soil organic carbon (SOC) pools are important for maintaining soil productivity and reducing the net CO2 loading of the atmosphere. An 18‐year old long‐term field experiment involving pearl millet‐cluster bean‐castor sequence was conducted on an Entisol in western India to examine the effects of chemical fertilizers and manuring on carbon pools in relation to crop productivity and C sequestration. The data showed that even the addition of 33.5 Mg ha−1 C inputs through crop residues as well as farm yard manure could not compensate the SOC depletion by oxidation and resulted in the net loss of 4.4 Mg C ha−1 in 18 years. The loss of SOC stock in the control was 12 Mg C ha−1. Conjunctive use of chemical fertilizers along with farm yard manure produced higher agronomic yields and reduced the rate of SOC depletion. The higher average seed yields of pearl millet (809 kg ha−1), cluster bean (576), and castor (827) over six cropping seasons were obtained through integrated use of fertilizers and manure. For every Mg increase in profile SOC stock, there was an overall increase of 0.46 Mg of crop yield, comprising increase in individual yield of pearl millet (0.17 Mg ha−1 y−1 Mg−1 SOC), cluster bean (0.14) and castor (0.15). The magnitude of SOC build up was proportional to the C inputs. Carbon pools were significantly correlated with SOC, which increased with application of organic amendments. Threshold C input of 3.3 Mg C ha−1 y−1 was needed to maintain the SOC stock even at the low antecedent level. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

20.
In the oldest sections of Burkina Faso's largest irrigation scheme in the Sourou Valley (13° 10′ N, 03° 30′W) rice (Oryza sativa L.) yields dropped from about 5 to 6 t ha−1 in the early 1990s, shortly after establishment of the scheme, to 2 to 4 t ha−1 from 1995 onwards. Farmers blamed this yield decline on the appearance of 2 to 20 m diameter low productive spots. According to farmers and field measurements, the low productive spots decreased yields by 25–50 per cent. The low productive spots are caused by Zn deficiency. Low Zn availability is related to the very low DTPA‐extractable Zn content of the soil (0·08–0·46 mg kg−1), the alkaline‐calcareous character of the soil, the non‐application of Zn fertilizers, and a relatively large P fertilizer dose (21 kg P ha−1). Farmers were correct in relating the calcareous nature of the soil to the presence of the low productive spots. They were instrumental in identifying application of decomposed organic resources (e.g. rice straw at 5 t ha−1) as a short‐term solution that increases yields by 1·5 to 2·0 t ha−1. Application of Zn fertilizer (10 kg Zn ha−1) in 29 farmer fields in the 2001 dry season eradicated the low productive spots and increased yields from 3·4 to 6·0 t ha−1. Although application of Zn fertilizer is strongly recommended, it is not yet available in Burkina Faso. Based on a comparison of fertilizer prices on the world market and the local market, we expect that the use of Zn fertilizers will be highly profitable (cost/value ratio ≫ 2). Despite the relatively recent introduction of irrigated rice cropping, most farmers showed a good understanding of cropping constraints and possible solutions. Both farmers and researchers mutually benefited from each other's knowledge and observations. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

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