Optimization of inter-seasonal nitrogen allocation increases yield and resource-use efficiency in a water-limited wheat-maize cropping system in the North China Plain

Winter wheat–summer maize cropping system in the North China Plain often experiences droughtinduced yield reduction in the wheat season and rainwater and nitrogen(N)fertilizer losses in the maize season.This study aimed to identify an optimal interseasonal water-and N-management strategy to alleviate these losses.Four ratios of allocation of 360 kg N ha^(-1)between the wheat and maize seasons under one-time presowing root-zone irrigation(W0)and additional jointing and anthesis irrigation(W2)in wheat and one irrigation after maize sowing were set as follows:N1(120:240),N2(180:180),N3(240:120)and N4(300:60).The results showed that under W0,the N3 treatment produced the highest annual yield,crop water productivity(WPC),and nitrogen partial factor productivity(PFPN).Increased N allocation in wheat under W0 improved wheat yield without affecting maize yield,as surplus nitrate after wheat harvest was retained in the topsoil layers and available for the subsequent maize.Under W2,annual yield was largest in the N2 treatment.The risk of nitrate leaching increased in W2 when N application rate in wheat exceeded that of the N2 treatment,especially in the wet year.Compared to W2N2,the W0N3 maintained 95.2%grain yield over two years.The WPCwas higher in the W0 treatment than in the W2 treatment.Therefore,following limited total N rate,an appropriate fertilizer N transfer from maize to wheat season had the potential of a“triple win”for high annual yield,WPCand PFPN in a water-limited wheat–maize cropping system.

Impact on Soil Organic C and Total Soil N from Cool- and Warm-Season Legumes Used in a Green Manure-Forage Cropping System

Annual forage legumes are important components of livestock production systems in East Texas and the southeastern US. Forage legumes contribute nitrogen (N) to cropping systems through biological N fixation, and their seasonal biomass production can be managed to complement forage grasses. Our research objectives were to evaluate both warm- and cool-season annual forage legumes as green manure for biomass, N content, ability to enhance soil organic carbon (SOC) and soil N, and impact on post season forage grass crops. Nine warm-season forage legumes (WSL) were spring planted and incorporated as green manure in the fall. Forage rye (Secale cereale L.) was planted following the incorporation of WSL treatments. Eight cool-season forage legumes (CSL) were fall planted in previously fallow plots and incorporated as green manure in late spring. Sorghum-sudangrass (Sorghum bicolor x Sorghum bicolor var. sudanense) was planted over all treatments in early summer after forage rye harvest and incorporation of CSL treatments. Sorghum-sudangrass was harvested in June, August and September, and treatments were evaluated for dry matter and N concentration. Soil cores were taken from each plot, split into depths of 0 to 15, 15 to 30 and 30 to 60 cm, and soil C and N were measured using combustion analysis. Nylon mesh bags containing plant samples were buried at 15 cm and used to evaluate decomposition rate of above ground legume biomass, including change in C and N concentrations. Mungbean (Vigna radiata L. [Wilczek]) had the highest shoot biomass yield (6.24 t DM ha-1) and contributed the most total N (167 kg∙ha-1) and total C (3043 kg∙ha-1) of the WSL tested. Decomposition rate of WSL biomass was rapid in the first 10 weeks and very slow afterward. Winter pea (Pisum sativum L. spp. sativum), arrow leaf clover (Trifolium vesiculosum Savi.), and crimson clover (Trifolium incarnatum L.) were the most productive CSL in this trial. Austrian winter pea produced 8.41 t DM ha-1 with a total N yield of 319 kg N ha-1 and total C production of 3835 kg C ha-1. The WSL treatments had only small effects on rye forage yield and N concentration, possibly due to mineralization of N from a large SOC pool already in place. The CSL treatments also had only minimal effects on sorghum-sudangrass forage production. Winter pea, arrow leaf and crimson clover were productive cool season legumes and could be useful as green manure crops. Mungbean and cowpea (Vigna unguiculata [L.] Walp.) were highly productive warm season legumes but may include more production risk in green manure systems due to soil moisture competition.

Soil carbon sequestration under long-term rice-based cropping systems of purple soil in Southwest China

Carbon sequestration in agricultural soils is a complex process controlled by farming practices, climate and some other environment factors. Since purple soils are unique in China and used as the main cropland in Sichuan Basin of China, it is of great importance to study and understand the impacts of different fertilizer amendments on soil organic carbon（SOC） changes with time. A research was carried out to investigate the relationship between soil carbon sequestration and organic carbon input as affected by different fertilizer treatments at two long-term rice-based cropping system experiments set up in early 1980 s. Each experiment consisted of six identical treatments, including（1） no fertilizer（CK）,（2） nitrogen and phosphorus fertilizers（NP）,（3） nitrogen, phosphorus and potassium fertilizers（NPK）,（4） fresh pig manure（M）,（5） nitrogen and phosphorus fertilizers plus manure（MNP）, and（6） nitrogen, phosphorus and potassium fertilizers plus manure（MNPK）. The results showed that annual harvestable carbon biomass was the highest in the treatment of MNPK, followed by MNP and NPK, then M and NP, and the lowest in CK. Most of fertilizer treatments resulted in a significant gain in SOC ranging from 6.48 to 2 9.13% compared with the CK, and raised soil carbon sequestration rate to 0.10–0.53 t ha–1 yr-1. Especially, addition of manure on the basis of mineral fertilizers was very conducive to SOC maintenance in this soil. SOC content and soil carbon sequestration rate under balanced fertilizer treatments（NPK and MNPK） in the calcareous purple soil（Suining） were higher than that in the acid purple soil（Leshan）. But carbon conversion rate at Leshan was 11.00%, almost 1.5 times of that（7.80%） at Suining. Significant linear correlations between soil carbon sequestration and carbon input were observed at both sites, signifying that the purple soil was not carbon-saturated and still had considerable potential to se questrate more carbon.

Economic Analysis of Diversified Rotational Cropping Systems in the Lateritic Belt of Lower Gangetic Plain of Eastern India

Economic analysis of different diversified rotational cropping systems under Farmers＇ package/practices and improved package/practices was conducted in Birbhum district, West Bengal, located in the red and lateritic belt of lower Gangetic plain of eastern lndia. Diversified triple cropping systems （peanut-brinjal＋brinjal, rice-potato-pumpkin, and cucumber-cabbage-basella） required higher cost for cultivation, but also produced higher rice equivalent yield, higher net return and higher return rupee1 invested in both management practices. Considering the resource-ability and risk-bearing capacity, and net return and return rupee^-1 （RPR） invested, these cropping systems can be recommended for resource-rich farmers. Rice-rapeseed-cowpea, rice-wheat-green gram and radish-tomato-amaranthus systems profitable. These cropping systems can be required less inputs for cultivation, were less risky, and economically viable and recommended for resource-poor farmers. Peanut-brinjal ＋ brinjal-okra-chilli ＋ chilli-cucumber-cabbage-basella system was the best among all the 3-year rotational systems in respect to RPR in both management practices. This rotational system will be suitable for resource-rich farmers. Vegetable-based rotational systems （ridge gourd-marigold-okra-black gram-pointed gourd ＋ pointed gourd-radish-tomato-amaranthus） or rice-based rotational system （rice-wheat-green gram-rice-rapeseed-cowpea-rice-potato-pumpkin） also found to be suitable to increase the profitability and system sustainability. These cropping systems can be recommended for all groups of farmers.

Variation of Physical and Chemical Properties of Soils under Different Cropping Systems in the Watershed of Kpocomey, Southern Benin

Soils degradation is one of the constraints in food security achievement in Benin. This study aimed at assessing the effect of cropping systems and slope on soil physical and chemical properties in the watershed of Kpacomey located in the Aplahoué district. Soil samples were collected from three parallel transects along the slope. Sampling was carried out under different treatments combining cropping systems (Maize-Cassava, pure Palm grove, Palm grove-Maize-Cassava and Teak Plantation) along with slope levels (low slope, medium slope and high slope degree). The impact of cropping systems and slope on soil properties was assessed by determining the physical and chemical parameters. The cropping systems significantly (p < 0.05) influenced soil bulk density, root biomass, soil acidity and soil organic matter. The lowest soil bulk density (1.38 g/cm3) was recorded under the Palm grove-Maize-Cassava cropping system while the highest (1.47 g/cm3) was obtained with pure Palm grove cropping system. Root biomass was more abundant (0.28%) with the pure Palm grove cropping system. However, root biomass was significantly (p < 0.05) influenced by slope. Soil crusting resulted in no significant influence (p > 0.05) on the effect of cropping systems and slope. Moreover, cropping systems resulted in significant effects (p < 0.05). Soil organic matter and soil-assimilated phosphorus content were significantly influenced by the effect of the slope. These findings indicated that cropping systems and slope are significant drivers in soil degradation in the Kpacomey watershed and bringing out cropping systems that best aim at soil conservation.

Residual Effect of Biochar on Soil Properties and Yield of Maize (<i>Zea mays L.</i>) under Different Cropping Systems

A field experiment was conducted to examine the residual influence of biochar applied previously to an established experiment at the Agriculture University Research Farm, Peshawar on soil properties and yield of maize crop during summer 2016. The experiment was established in RCB design with split plot arrangements having cropping systems (CS) in main plots and biochar (BC) in sub-plots. Cropping systems were: 1) wheat-mung bean;2) wheat-maize;3) chickpea-maize;and 4) chickpea-mung bean. During the past three seasons, each cropping system received biochar at 0, 40, 60 and 80 t&#183ha&#451 along with recommended dose of NPK in each season. For this study, maize was planted after chickpea and wheat in summer 2016. The results showed that grain yield, cobs weight and total N uptake of maize was significantly greater for chickpea-maize than for wheat-maize cropping system. Soil organic C was also significantly higher in soil under chickpea-maize than under wheat-maize cropping system. However, other yield components such as stover yield, harvest index and N concentration in grain and stover of maize and soil properties such as pH, EC and mineral N were non-significantly affected by cropping systems. With respect to residual effect of biochar grain yield of maize and bulk density of soil were maximum for treatment receiving biochar at 40 t&#183ha&#451 whereas cobs weight soil pH and mineral N were highest receiving biochar at 60 t&#183ha&#451. Moreover, N concentration in stover, N uptake and soil organic C were maximum for treatment receiving biochar at 80 t&#183ha&#451. However, stover yield, harvest index, N concentration in grain, and soil EC were non-significantly affected by biochar treatments. However interactions between CS × BC were significant for yield and yield parameters of maize and for soil properties (bulk density mineral N), while non-significant for harvest index, soil organic C, pH and EC. It was concluded that chickpea-maize cropping system performed better in terms of improving yield and yield components of maize and in improving soil properties. Application of biochar to previous crops also improved yield and yield parameters of the following maize as well as soil properties. Thus we recommend that legumes must be involved in cropping system for sustainable and higher productivity and improved soil properties. However, further studies are suggested to find out suitable dose of biochar for sustainable and economic crop productivity and soil fertility.

Tillage, crop residue, and nutrient management effects on.soil organic carbon in rice-based cropping systems： A review

Soil organic carbon （SOC） sequestration is one of the major agricultural strategies to mitigate greenhouse gas （GHG） emissions, enhance food security, and improve agricultural sustainability. This paper synthesizes the much-needed state- of-knowledge on the effects of tillage, crop residue, and nutrient management practices on SOC sequestration and identifies potential research gap, opportunities, and challenges in studying SOC dynamics in rice （Oryza sativa L.）-based cropping systems in South Asia, mainly in Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka. Improved management prac- tices such as reduced- and no-tillage management, nitrogen （N） fertilizer and farmyard manure （FYM） application, and crop residue addition can improve SOC accumulation. Positive effects of no-tillage, crop residue addition, N addition through manure or compost application, and integration of organic and chemical fertilizers on SOC accumulation in rice-based cropping systems have been documented from South Asia. However, limited data and enormous discrepancies in SOC measurements across the region exist as the greatest challenge in increasing SOC sequestration and improving agricultural sustainability. More research on SOC as influenced by alternative tillage, crop residue, and nutrient management systems, and development of SOC monitoring system for existing long-term experiments will advance our understanding of the SOC dynamics in rice-based cropping systems and improve agricultural system sustainability in South Asia.

Technical efficiency and its determinants of the various cropping systems in the purple-soiled,hilly region of southwestern China

This study examines the technical efficiency(TE) differences among typical cropping systems of smallholder farmers in the purple-soiled hilly region of southwestern China.Household-,plot-,and crop-level data and community surveys were conducted to explore TE levels and determinants of typical cropping systems by using a translog stochastic frontier production function.Results indicate significant difference in TE and its determinants among cropping systems.The mean TEs of the rice cropping system(R),the rice-rape cropping system(RR),the rice-rape-potato cropping system(RRP),and the oil cropping system(O) are0.86,0.90,0.84,and 0.85,respectively,which are over 1.17 times higher than those of the maize-sweet potato-other crop cropping system(MSO) and the maize-sweet potato-wheat cropping system(MSW) at0.78 and 0.69,respectively.Moreover,Technical inefficiency(TIE) of different cropping systems is significantly affected by characteristics of the household as well as plot.However,the impact of land quality,mechanical cultivation conditions,crop structure,farming system,farm radius,household type,cultivated land area per capita,and annual household income per capitalon TIE vary by cropping system.Additionally,output elasticity of land,labor,and capital,as a group,is greater than the one of agricultural machinery and irrigation.Finally,when household-owned effective agricultural labor is at full farming capacity,optimal plot sizes for the R,RR,RRP,MSO,MSW,and 0 cropping systems are 1.12hm^2,0.35 hm^2,0.25 hm^2,2.82 hm^2,1.87 hm^2,and 1.17hm^2,respectively.

The Effects of Climate Change on the Planting Boundary and Potential Yield for Different Rice Cropping Systems in Southern China

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.

Possible Trajectories of Agricultural Cropping Systems in China from 2011 to 2050

Predicting the possible impacts of future climate change on cropping systems can provide important theoretical support for reforming cropping system and adjusting the distribution of agricultural production in the future. The study was based on the daily data of future B2 climate scenario (2011-2050) and baseline climate condition (1961-1990) from high resolution regional climate model PRECIS (~50 km grid interval). According to climatic divisions of cropping systems in China, the active accumulated temperature stably passing the daily average temperature of 0°C, the extreme minimum temperature and the termination date passing the daily average temperature of 20°C which were justified by dominance as a limitation of different cropping systems in zero-grade zone were investigated. In addition, the possible trajectories of different cropping systems in China from 2011 to 2050 were also analyzed and assessed. Under the projected future B2 climate scenario, from 2011 to 2050, the northern boundaries of double cropping area and triple cropping area would move northward markedly. The most of the present double cropping area would be replaced by the different triple cropping patterns, while current double cropping area would shift towards areas presently dominated by single cropping systems. Thus the shift of multiple cropping areas would lead to a significant decrease of single cropping area. Compared with China’s land area, the percentage cover of single cropping area and double cropping area would decrease slowly, while percentage cover of triple cropping area would gradually increase.

Wheat, maize and sunflower cropping systems selectively influence bacteria community structure and diversity in their and succeeding crop's rhizosphere

supported by the Special Fund for Agro-scientific Research in the Public Interest in China （201103001）

Effects of Residue Management and Cropping Systems on Wheat Yield Stability in a Semiarid Mediterranean Clay Soil

Agriculture is the single biggest user of land and water in Morocco;however its performances are still low due to high rainfall variation and rates of soil productivity depletion. Increasing concerns about soil and environment quality degradation have raised the need to review existing tillage management systems and develop new systems for seed-bed preparation. Consequently, No-tillage is found a promising practice of soil management to improve simultaneously soil quality and wheat production in semiarid Morocco. However, residue management under No-tillage was Not yet studied in conjunction with wheat rotation. Therefore, a field study was conducted in the semiarid Chaouia Plain of Morocco during the period from 1994 to 2003, in order to evaluate the impacts of different tillage practices (conventional tillage (CT), No-tillage (NT));No-tillage wheat residue management scenarios (total NTr, partial NTp and No-removal of residues NTm) and crop rotations (continuous wheat (CW), Wheat-Fallow (WF), Wheat-Maize-Fallow (WMF), Wheat-Lentil-Fallow (WLF) and Wheat-Barley-Fallow (WBF)) on wheat production. Over-years, conventional tillage system permitted lower yield of wheat while NT maintenance of crop residue at the surface is needed to increase it. Basically, NTp could be adopted in mixed crop-livestock systems of semiarid areas for the purpose of guarantying grain and feed. Wheat yields were the lowest under continuous wheat for all years. Wheat-fallow rotation is an important option in dry years or areas, while wheat-fallow-lentil or barley rotations are recommended in better environments. Stability analysis indicated that yields in the No-tillage system were less influenced by adverse growing conditions than conventional tillage system, particularly under low rainfall. These results indicate that improved soil quality under No-tillage enhanced wheat yield stability by reducing the impact of adverse growing conditions.

Survey of Rice Cropping Systems in Kampong Chhnang Province,Cambodia

Although Cambodia might have achieved self-sufficiency and an exported surplus in rice production,its rice-based farming systems are widely associated with low productivity,low farmer income and rural poverty.The study is based on a questionnaire village survey in 14 communes containing 97 villages of Kampong Chhnang Province from March to June,2011.It analyzes the prevailing rice-based cropping systems and evaluates options for their improvement.Differences in cropping systems depend on the distance from the Tonle Sap water bodies.At distances greater than 10 km,transplanted wet-season rice cropping system with low productivity of about 1.6 t/hm 2 prevails.This deficiency can be primarily attributed to soils with high coarse sand fractions and low pH （〈 4.0）,use of ＇late＇ cultivars,and exclusive use of self-propagated seeds.To improve this cropping system,commercial ＇medium＇ cultivars help prevent crop failure by shortening the cultivation period by one month and complementation of wet-season rice with non-rice crops should be expanded.Areas adjacent （≤ 1 km） to the water bodies become inundated for up to seven months between July until January of each year.In this area,soils contain more fine sand,silt and clay,and their pH is higher （〉 4.0）.Farmers predominantly cultivate dry-season recession rice between January and April.Seventy-nine percent of the area is sown directly and harvested by combines.Adoption ratio of commercial rice seeds is 59% and yields average 3.2 t/hm 2.Introduction of the second dry-season rice between April and July may double annual yields in this rice cropping system.Besides upgrading other cultivation technologies,using seeds from commercial sources will improve yield and rice quality.Along with rice,farmers grow non-rice crops at different intensities ranging from single annual crops to intensive sequences at low yields.

Cropping Systems to Improve Carbon Sequestration for Mitigation of Climate Change

The recent trend of an increase in the concentration of greenhouse gases (GHGs) in the atmosphere has led to an ele-vated concern and urgency to adopt measures for carbon (C) sequestration to mitigate the climate change. Among all GHGs, carbon dioxide (CO2) is the most important one which occurs in the greatest concentration and has the strong-est radiative forcing among all. Reducing the release of CO2 to the atmosphere through “green energy” technologies or fossil fuel energy alternatives, such as wind, solar and hydraulic energies, is a major challenge. However, removal of atmospheric CO2 by terrestrial ecosystems via C sequestration and converting the sequestered C into the soil organic C has provided a great opportunity for shifting GHG emission to mitigate the climate change. Soil is an ideal reservoir for storage of organic C since soil organic C has been depleted due to land misuse and inappropriate management through the long history. To optimize the efficiency of C sequestration in agriculture, cropping systems, such as crop rotation, intercropping, cover cropping, etc., play a critical role by influencing optimal yield, total increased C sequestered with biomass, and that remained in the soil. As matter of fact, soil C sequestration is a multiple purpose strategy. It restores degraded soils, enhances the land productivity, improves the diversity, protects the environment and reduces the enrichment of atmospheric CO2, hence shifts emission of GHGs and mitigates climate change.

Experiences and Research Perspectives on Sustainable Development of Rice-Wheat Cropping Systems in the Chengdu Plain, China

The rice and wheat cropping pattern is one of the main cropping systems in the world. A large number of research results showed that successive cropping of rice and wheat resulted in a series of problems such as hindering nutrition absorption, gradual degeneration of soil fertility, decline of soil organic matter, and increased incidence of diseases and pests. In China, especially in the Chengdu plain where rice-wheat cropping system is practiced, productivity and soil fertility was enhanced and sustained. This paper reviews the relevant data and experiences on rice-wheat cropping in the Chengdu Plain from 1977 to 2006. The principal sustainable strategies used for rice-wheat cropping systems in Chengdu Plain included： 1） creating a favorable environment and viable rotations; 2） balanced fertilization for maintenance of sustainable soil productivity; 3） improvement of crop management for higher efficiency; and 4） use the newest cultivars and cultivation techniques to upgrade the production level. Future research is also discussed in the paper as： 1） the constant topic： a highly productive and efficient rice-wheat cropping system for sustainable growth; 2） the future trend： simplified cultivation techniques for the rice-wheat cropping system; 3） the foundation： basic research for continuous innovation needed for intensive cropping. It is concluded that in the rice-wheat cropping system, a scientific and reasonable tillage/cultivation method can not only avoid the degradation of soil productivity, but also maintain sustainable growth in the long run.

Phosphorus losses via surface runoff in rice-wheat cropping systems as impacted by rainfall regimes and fertilizer applications

Phosphorus（P） losses from agricultural soils contribute to eutrophication of surface waters. This field plot study investigated effects of rainfall regimes and P applications on P loss by surface runoff from rice（Oryza sativa L.） and wheat（Triticum aestivum L.） cropping systems in Lake Taihu region, China. The study was conducted on two types of paddy soils（Hydromorphic at Anzhen site, Wuxi City, and Degleyed at Xinzhuang site, Changshu City, Jiangsu Province） with different P status, and it covered 3 years with low, high and normal rainfall regimes. Four rates of mineral P fertilizer, i.e., no P（control）, 30 kg P ha^（–1） for rice and 20 kg P ha^（–1） for wheat（P_（30＋20））, 75 plus 40（P_（75＋40））, and 150 plus 80（P_（150＋80））, were applied as treatments. Runoff water from individual plots and runoff events was recorded and analyzed for total P and dissolved reactive P concentrations. Losses of total P and dissolved reactive P significantly increased with rainfall depth and P rates（P〈0.0001）. Annual total P losses ranged from 0.36–0.92 kg ha^–1 in control to 1.13–4.67 kg ha^–1 in P150＋80 at Anzhen, and correspondingly from 0.36–0.48 kg h^–1 to 1.26–1.88 kg ha^–1 at Xinzhuang, with 16–49% of total P as dissolved reactive P. In particular, large amounts of P were lost during heavy rainfall events that occurred shortly after P applications at Anzhen. On average of all P treatments, rice growing season constituted 37–86% of annual total P loss at Anzhen and 28–44% of that at Xinzhuang. In both crop seasons, P concentrations peaked in the first runoff events and decreased with time. During rice growing season, runoff P concentrations positively correlated（P〈0.0001） with P concentrations in field ponding water that was intentionally enclosed by construction of field bund. The relative high P loss during wheat growing season at Xinzhuang was due to high soil P status. In conclusion, P should be applied at rates balancing crop removal（20–30 kg P ha^–1 in this study） and at time excluding heavy rains. Moreover, irrigation and drainage water should be appropriately managed to reduce runoff P losses from rice-wheat cropping systems.

Weed Incidences and Their Effect on Crop Productivity under Diversified Rotational Cropping Systems in the Lateritic Belt of Lower Gangetic Plain of Eastern India

A field experiment was conducted from 2002-2005 on a sandy clay loam red and lateritic soil under irrigation in a farmer＇s field at Senkapur （Lat. 23°36.79′ N, Long. 87°38.14′E, Elev. 46 m AMSL）, Birbhum, West Bengal, India. The objective was to provide the temporal changes of weed diversity and density, ecology, and impact of rotational cropping systems on different crops under double and triple cropping systems with improved （IP） and farmer＇s packages （FP）. There was significantly higher weed density in FP than in IP on all years. Grasses and sedges were more in vegetable-based rotational systems; but grasses and broad leaf weeds （BLWs） were more in rice-based rotational systems. The lowest weed population was in vegetable-based systems. Grasses increased in rice-based systems but gradually decreased in vegetable-based systems in subsequent years. Sedge density was higher in vegetable- than in rice-based rotational systems. Density of BLWs was higher but that of sedges was lower in rice-based rotational systems as compared to vegetable-based systems. Density of BLWs gradually decreased in all rotational systems over the years in both packages. Density of weeds decreased gradually in subsequent years indicating the positive effect of rotational systems on suppression of weeds. Results indicate that the weed density can be reduced through judicious diversified rotational cropping systems. Peanut-brinjal＋brinjal, okra-chilli＋chilli and cucumber-cabbage-basella systems greatly reduced the weed density in both packages, and hence can be recommended for the lateritic belt of lower Gangetic plain of eastern India.

Contribution of Multiple Cropping Systems to Greenhouse Gas Mitigation in the Municipality of Abomey-Calavi in Southern Benin

In the world at large, while agricultural yields are increasing with constant land area, in Sub-Saharan Africa, more land is needed to increase production. In this region of Africa, agriculture therefore remains essentially extensive and contributes to environmental degradation, especially deforestation. Thus, the objective of this research is to assess and compare the quantities of greenhouse gases produced by multiple and mono-specific cropping systems. To this end, the quantity of greenhouse gases (GHG) produced by several cropping systems installed on an experimental farm in Kpotomey in the municipality of Abomey-Calavi (Benin) was estimated. The estimation of GHG quantities was made on the basis of IPCC work and data from the experiments carried out. Comparisons were made between mono-specific crops and multiple crops. The results show that the quantities of GHG emitted per ton of production are more or less identical and vary on average from 0.6 to 0.11 teqCO2. However, the advantage of multiple cropping systems is that they reduce the clearing of new land and thus avoid about 31.5 tons of CO2 if the plant formation to be replaced was a forest. Multiple cropping with moderate fertilization in the presence of organic matter increases production while preserving the environment.

Triple Cropping Systems of Spring Maize, Tropical Grass of Teff (<i>Eragrostis tef</i>) and Winter Cereal Crops to Combine Total Digestible Nutrient Yield with Protein Concentration in Southern Kyushu, Japan

It is ordinarily common for forage production in southern Kyushu to adopt a double cropping system, composed of summer forage crops (e.g. maize and sorghum) cultivated from late March to early September, and winter grass crops (e.g. Italian ryegrass (IR) and oat) from mid-October to the following May. However, if high total digestible nutrient (TDN) production is aimed to introduce winter cereal crops (e.g. wheat and barley) as a replacement of IR, it is necessary to cultivate tropical grass, which has a rapid-growth potential with high crude protein (CP) concentration in a switching period between summer and winter crops. In this study, teff (Eragrostis tef) was tried to evaluate as a candidate crop in the switching period. Yield and quality of two types of triple forage cropping system were determined under maize-teff-barley and maize-teff-wheat in the first and second year, respectively. Compared with the normal year, summer temperature was higher and summer and winter precipitations were lower in the first year, while no climatic disorder was observed in the second year. Even though dry matter yield of teff was minimal in the present system due to weed damage, CP concentration was the highest among crops and TDN yields of the present cropping system tended to be higher in the second year with no drought stress than in the conventional maize-IR system in the region.

Effect of Long-Term Application of K Fertilizer and Wheat Straw to Soil on Crop Yield and Soil K Under Different Planting Systems

Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.