Fertilization and Soil Ploughing Practices under Changing Physical Environment Lead to Soil Organic Carbon Dynamics under Conservation Agriculture in Rice-Wheat Cropping System: A Scoping Review

Ploughing and fertilization practices in rice-wheat system have deteriorated the soil carbon (C) pools. Conservation agriculture (CA) based management approaches have proven to enhance C sequestration and reverse the loss of soil-organic-carbon (SOC), which further enhances soil fertility. Different fractions of SOC pools react to the alterations in management practices and indicate changes in SOC dynamics as compared to total C in the soil. Higher SOC levels in soil have been observed in case of reduced/no-till (NT) practices than conventional tillage (CT). However, between CT and zero tillage/NT, total SOC stocks diminished with an increase in soil depth, which demonstrated that the benefits of SOC are more pronounced in the topsoil under NT. Soil aggregation provides physical protection to C associated with different-sized particles, thus, the improvement in soil aggregation through CA is an effective way to mitigate soil C loss. Along with less soil disturbance, residual management, suitable crop rotation, rational application of manures and fertilizers, and integrated nutrient management have been found to be effective in not only improving soil C stock but also enhancing the soil health and productivity. Thus, CA can be considered as a potential method in the build-up of SOC of soil in rice-wheat system.

Climate change adaptation, greenhouse gas mitigation and economic profitability of conservation agriculture: Some examples from cereal systems of Indo-Gangetic Plains

Achieving sustainability of the cereal system in the Indo-Gangetic Plains（IGP）of India under progressive climate change and variability necessitates adoption of practices and technologies that increase food production,adaptation and mitigation in a sustainable way.This paper examines conservation agriculture（CA）from the perspective of：（i）increased yield and farm income,（ii）adaptation to heat and water stresses,and（iii）reduction in greenhouse gas（GHGs）emissions.The analyses and conclusions are based on the literature and evidences from a large number of on-station as well as farmers’field trials on CA in the cereal systems of IGP.Our analyses show that CA-based system substantially reduces the production cost（up to 23%）but produces equal or even higher than conventional system;thereby increasing economic profitability of production system.CA-based production systems also moderated the effect of high temperature（reduced canopy temperature by 1–4°C）and increased irrigation water productivity by 66–100%compared to traditional production systems thus well adapting to water and heat stress situations of IGP.Our continuous monitoring of soil flux of CO2,N2O and CH4 revealed that CA-based rice-wheat systems emit 10–15%less GHGs than conventional systems.This is the first time that CA and its components are synthesized and analyzed from food security-climate change nexus.From this holistic analysis,we suggest that wide-scale promotion of suitable CA practices by integrating into national agriculture development strategy is a way forward to address food security,climate change adaptation and mitigation challenges faced by present agriculture.

Factors Affecting Adoption of Conservation Agriculture Practices in Mpatsa Extension Planning Area, Nsanje, Southern Malawi

Conservation agriculture (CA) emerged as an alternative innovation to conventional agriculture due to losses in soil productivity as a result of soil degradation. This study investigated factors affecting the adoption of Conservation Agriculture in the Mpatsa Extension Planning Area in a southern district of Malawi, Nsanje. A quantitative method approach was followed where were collected from a sample of 110 targeted smallholder farmers in the study area using a semi-structured questionnaire where the majority (63.6%) were women. Focused Group Discussions (FGDs) were also done to triangulate data on questionnaires. Data were entered into a Microsoft Excel database and analyzed in SPSS version 20. Socio-economic, environmental factors and household income have a greater impact on the adoption of conservation agricultural innovations. Animals were found to cause permanent soil cover disturbance while feeding on crop residues leaving the soil bare. The study concluded that climatic factors and CA training have negatively affected the adoption of new agricultural innovations, therefore, recommending further training and extension support for CA adoption as well as more access to credit opportunities for increased households’ adoption of CA.

Effective Approaches to Wheat Improvement in Kazakhstan： Breeding and Conservation Agriculture

International Maize and Wheat Improvement Center （CIMMYT） and Kazakhstan collaborative activities on wheat improvement are focused in the following main areas： （1） wheat germplasm enhancement： Kazakhstan-Siberian Network on Wheat Improvement （KASIB） and Shuttle Breeding ＂Mexico-KASIB＂ Programs; （2） Conservation agriculture （CA） for wheat production and crop diversification. Nineteen breeding programs of Kazakhstan and Russia are united by KASIB Network and Shuttle Breeding. By 2014, more than 15,000 wheat lines and varieties were involved in breeding programs of Kazakhstan and Russia; 10 varieties were developed and released. The KASIB Network and Shuttle Breeding Program were recognized as one of the best example of the effective regional and international cooperation in Kazakhstan and Russia. In the beginning of 2000 CIMMYT, National Agricultural Research System, the Ministry of Agriculture, FAO, World Bank in cooperation with farmers initiated large-scale activities based on CA in Kazakhstan. Due the joint efforts, area under CA-based practices has been increasing from virtually none to an estimated area of 500,000 ha in 2007, 1,200,000 ha in 2008, 2,000,000 ha in 2014 with continued rapid increases in area. Kazakhstan is now included among the top ten countries with the largest areas under no-tillage in the world.

On-Station and On-Farm Assessment of the Effects of Soil Cover on Conservation Agriculture Performances in Western Burkina Faso

Conservation agriculture (CA) is one option for dealing with such a challenge, but its main difficulty in West Africa is in maintaining permanent soil cover, particularly with crop residues, due to their preferential use for livestock fodder. The aim of our study was to determine the effect of crop residue mulching on the efficiency of cropping systems based on the principles of conservation agriculture. The experimental design was based on on-station experiments, intended to assess the specific effect of different levels of crop residue mulching on the biological and chemical soil fertility parameters, while in on-farm experiments we mainly assessed the ability of farmers to actually collect crop residues for soil cover and the associated effects on weeds and yields. The on-station experimental design was in fully randomized factorial blocks comprising five treatments and three replicates. The treatments compared the conventional system, tillage and cropping without mulching, and CA systems with 1 ton, 2 tons, and 4 tons of straw per hectare in plots of 10 m2. The effects of CA on the macrofauna, respiratory activity, and soil chemical parameters were evaluated in the 2014 and 2015 growing seasons. For the on-farm experiments, the conventional and CA practices of 15 farmers were compared to conventional practices in 2013 and 2014 in plots of 626 m2. The on-station results showed that the presence of crop residue mulching induced an increase in the density of termites. A significant release of carbon dioxide (CO2) in the CA treatments compared to the conventional treatment was also observed. For the chemical parameters (pH, N, P and K) were significantly and positively affected by mulch in the top 5 centimeters of soil. The on-farm experiments confirmed the difficulty of farmers in collecting enough biomass, with negative effects on grass cover leading to generally lower yields than conventional treatments. Other practices also affected the results, such as the maize sowing date, the gap between sowing and weeding, the gap between sowing and urea supply, the number of years of CA practices in the plot and, the gap between maize sowing and cowpea sowing. For the farmers having the human resources to collect enough crop residues for soil cover and follow the steps of the crop management sequences, it was possible to maintain yields compared to the conventional practice.

An examination of thematic research,development,and trends in remote sensing applied to conservation agriculture

Conservation agriculture seeks to reduce environmental degradation through sustainable management of agricultural land.Since the 1990s,agricultural research has been conducted using remote sensing technologies;however,few previous reviews have been conducted focused on different conservation management practices.Most of the previous literature has focused on the application of remote sensing in agriculture without focusing exclusively on conservation practices,with some only providing a narrative review,others using biophysical remote sensing for quantitative estimates of the bio-geo-chemical-physical properties of soils and crops,and few others focused on single agricultural management practices.This paper used the preferred reporting items for systematic review(PRISMA)methodology to examine the last 30 years of thematic research,development,and trends associated with remote sensing technologies and methods applied to conservation agriculture research at various spatial and temporal scales.A set of predefined key concepts and keywords were applied in three databases:Scopus,Web of Science,and Google Scholar.A total of 188 articles were compiled for initial examination,where 68 articles were selected for final analysis and grouped into cover crops,crop residue,crop rotation,mulching,and tillage practices.Publications on conservation agriculture research using remote sensing have been increasing since 1991 and peaked at 10 publications in 2020.Among the 68 articles,94%used a pixel-based,while only 6%used an object-based classification method.Prior to 2005,tillage practices were abundantly studied,then crop residue was a focused theme between 2004 and 2012.From 2012 to 2020,the focus shifted again to cover crops.Ten spectral indices were used in 76%of the 68 studies.This examination offered a summary of the new potential and identifies crucial future research needs and directions that could improve the contribution of remote sensing to the provision of long-term operational services for various conservation agriculture applications.

The transformation of agriculture in Brazil through development and adoption of Zero Tillage Conservation Agriculture

The soil conservation movement in Brazil has been a major driving force in the continuing search for agricultural farming systems that are more sustainable than what we have today,particularly in tropical and subtropical areas.The development and adoption of Zero Tillage Conservation Agriculture(ZT/CA)was the key to the success of this movement,generating agricultural,environmental,and societal benefits.Adoption of the ZT/CA philosophy and technologies is currently practiced on more than 50%of the annual crop area.This is due to the work and innovations of pioneering farmers,agronomists,researchers,and consultants that were and are involved in these efforts.This extensive adoption of ZT/CA occurred after many unsuccessful efforts to mitigate against the devastating effects of soil erosion that were threatening the entire agricultural industry in Brazil.Technicians and farmers realized that erosion control required continual cover of the soil to guard against the torrential rain storms common to these regions.This triggered the efforts of soil conservation pioneers at different points in time and regions of Brazil.In southern Brazil,Herbert Bartz,watched his topsoil eroding away in torrents of runoff.This set him thinking and searching for alternatives,resulting in his adoption of ZT/CA farming in 1972.Ten years later in Brazil’s centre-western savannah(Cerrado biome),farmers,researchers,crop consultants and agro-industry initiated efforts to expand cultivation into the very difficult production region of the Cerrados.This was successfully achieved through the pioneering work of agronomist John Landers,bringing experience from the ZT/CA farmer association networks in the south.These were the turning points in the sustainable development of annual crop farming in Brazil.Today,society recognizes the role of these pioneers as key to achieving social,economic and environmental sustainability.ZT/CA reversed the historically accelerating degradation of soil organic matter and soil structure by abandoning conventional tillage,thus improving soil physical and chemical characteristics.This was achieved by promoting cover cropping and permanent soil cover with crop residues,crop rotations,and complementary,environmentally suitable soil management technologies.

Current status,prospect and policy and institutional support for Conservation Agriculture in the Asia-Pacific region

The current growing demand for Conservation Agriculture(CA)at the national level in the countries of the Asia-Pacific region presents an opportunity to promote its widespread adoption and up-scaling through national policy and institutional support that appears necessary.Despite the obvious benefits of CA,it does not spread automatically unless the constraints that hinder adoption are understood and addressed in specific situations.These can include a combination of intellectual,social,financial,biophysical,technical,infrastructure constraints,or policy related support.Knowing what the bottlenecks are is important in developing strategies to overcome them.This paper presents:(a)some of the generic policy opportunities that exist for the adoption and uptake of CA;(b)a summary proceedings and outcome of the Regional Expert Consultation Workshop held in Beijing and sponsored by FAO Regional Office for Asia-Pacific which describes the status of CA in the Asia-Pacific region;(c)the challenges to CA adoption and uptake in the Asia-Pacific region;and(d)the conditions that need to be taken into account in designing and promoting policy and institutional support strategies for up-scaling CA.

Thoughts on developing small/medium size no-till equipment for conservation agriculture in Asia:Summary of post-publication peer review comments

Traditional agriculture bases most of its operations or practices on soil tillage,which causes likely occurrence of water and soil erosion and sediment runoff.In order to conserve soil,water and environment,Conservation agriculture(CA)is increasingly adopted to replace traditional tillage agriculture to achieve sustainable and profitable agriculture and subsequently improve the livelihoods of farmers.CA holds great potential for all sizes of farms and agro-ecological systems,but its adoption is most urgently required by smallholder farmers,especially those short of laborers.Small/medium size no-till machines and implements are the key to CA adoption.A review article on small/medium size no/minimum-till seeders in Asia published in IJABE triggers a lot of scientific conversation on how to develop suitable no-till equipment among peer experts.This paper presents a collection of these post-publication peer review comments including commentary,questions,answers,suggestions,critical thinking,etc.The authors of the review article also provide response,summary of the review comments and their own standpoints.This open post-publication review and commentary may add value to the published review article and provide new ideas useful for future research and development of CA equipment.

Conservation agriculture in India-Problems,prospects and policy issues

Conservation agriculture(CA)technologies involve minimum soil disturbance,permanent soil cover through crop residues or cover crops,and crop rotations for achieving higher productivity.In India,efforts to develop,refine and disseminate conservation-based agricultural technologies have been underway for nearly two decades and made significant progress since then even though there are several constraints that affect adoption of CA.Particularly,tremendous efforts have been made on no-till in wheat under a rice-wheat rotation in the Indo-Gangetic plains.There are more payoffs than tradeoffs for adoption of CA but the equilibrium among the two was understood by both adopters and promoters.The technologies of CA provide opportunities to reduce the cost of production,save water and nutrients,increase yields,increase crop diversification,improve efficient use of resources,and benefit the environment.However,there are still constraints for promotion of CA technologies,such as lack of appropriate seeders especially for small and medium scale farmers,competition of crop residues between CA use and livestock feeding,burning of crop residues,availability of skilled and scientific manpower and overcoming the bias or mindset about tillage.The need to develop the policy frame and strategies is urgent to promote CA in the region.This article reviews the emerging concerns due to continuous adoption of conventional agriculture systems,and analyses the constraints,prospects,policy issues and research needs for conservation agriculture in India.

The development of Conservation Agriculture in Australia--Farmers as innovators

The Australian story of farmer innovation in Conservation Agriculture reveals a complex interplay of policy,economics,science,and farming.Farmer experimentation with Conservation Agriculture began in the 1960’s and has continued to this day where around 80%-90%of Australia’s 23.5 million hectares of winter crops are now grown using Conservation Agriculture principles.This remarkable achievement is the result of both sustained investment in agricultural research and development and farmer innovation.Australian economic settings and science policies have encouraged and facilitated farmer participation in the Conservation Agricultural innovation system.Australian farmers have embraced Conservation Agriculture because it has met their needs,maintaining productivity and profitability in the face of declining terms of trade,and sustainably intensifying production with enhanced environmental outcomes.Drawing on individual farmer case studies,the specific strengths of farmer innovation are identified and the enabling conditions necessary for farmer innovation to flourish are discussed.

Soil carbon sequestration,carbon markets,and conservation agriculture practices:A hypothetical examination in Mozambique

Payments for Environmental Services(PES)are relatively novel mechanisms whereby the adoption of sustainable management practices by a stakeholder is rewarded by incentives linked to external markets.Adoption of PES for conservation agricultural practices(CAPS)by smallholder farmers may provide opportunities to increase household income or cover the technology costs of adoption if the carbon sequestration benefits of CAPS are quantifiable,adoption rates are accelerated and maintained,a mechanism exists whereby carbon sequestration services can be compensated,and carbon offset exchange markets are viable.This research suggests a methodology to examine a PES market for carbon offsets generated by the adoption of CAPS by farmers in Mozambique.Assuming a cumulative adoption of 60%over a 20-year period,revenue from PES market participation to CA adopters was two times higher than revenue earned when disadoption occurred midway through the simulation.Lower adoption targets are associated with higher per household returns when fertilizer rates typical to the region are increased.Establishing and maintaining a sustainable PES system in the study region would require significant investment in time and resources.The lack of on-the-ground institutions or local support for such a program would also challenge successful implementation.Finally,the programs where participant success depends on external markets,such as the hypothetical one suggested here,are subject to the ebb and flow of foreign demand for carbon offsets.Addressing these three broad constraints to a PES/CAPS program in the region would require grass-roots driven policy initiatives with buy-in at multiple social,economic,and political levels.

Conservation Agriculture in Europe

The adoption of Conservation Agriculture(CA)in Europe varies according to the ecological regions of the continent.Although Europe is behind other countries in adoption of CA,the indicators for future progress are encouraging.The area where CA is applied is growing rapidly because of increasing environmental awareness,including soil protection,and because of the need to reduce production costs.The European Conservation Agriculture Federation(ECAF)plays an important role in the adoption and dissemination of CA practices,and in discussions involving CA and the EU Common Agricultural Policy(CAP)reform.Yield performance and stability,operating costs,environmental policies and programs of the Common Agricultural Policy(CAP),and climate change will likely be the major driving forces defining the direction and for the extension of CA in Europe.The role of agriculture in climate change mitigation in the EU is discussed in the paper.

Effects of Conservation Agriculture on Land and Water Productivity in Yellow River Basin, China

In the dryland regions of North China,water is the limiting factor for rainfed crop production.Conservation agriculture(featuring reduced or zero tillage,mulching,crop rotations and cover crops)has been proposed to improve soil and water conservation and enhance yields in these areas.Conservation agriculture systems typically result in increased crop water availability and agro-ecosystem productivity,and reduced soil erosion.To evaluate the potential of conservation agriculture to improve soil water balance and agricultural productivity,the DSSAT crop model was calibrated using the data of a field experiment in Shouyang County in the semi-arid northeastern part of the Yellow River Basin.The average annual precipitation at the site is 472 mm,75%of which falls during the growing season.The site had a maize-fallow-maize rotation.data from two crop seasons(2005 and 2006)and four treatments for calibration and analysis were used.The treatments were:conventional tillage(CT),no-till with straw mulching(NTSM),all-straw incorporated(ASRT)and one-third residue left on the surface with no-till(RRT).The calibration results gave satisfactory agreement between field observed and model predicted values for crop yield for all treatments except RRT treatment,and for soil water content of different layers in the 150 cm soil profile for all treatments.The difference between observed and predicted values was in the range of 3%-25%for maize yield and RMSE was in the range of 0.03-0.06 cm^(3)/cm^(3) for soil water content measured periodically each cropping season.While these results are encouraging,more rigorous calibration and independent model evaluation are warranted prior to making recommendations based on model simulations.Medium-term simulations(1995-2004)were conducted for three of the treatments using the calibrated model.The NTSM and ASRT treatments had similar or higher yields(by up to 36%),higher crop water productivity by up to 28%and reduced runoff of up to 93%or 43 mm compared to CT treatment.

Physico-chemical properties and macrofauna of soils under various farming systems of cold arid region in Balochistan,Pakistan

Barshore is a small village in the Pishin District,Balochistan,Pakistan,with dry summers and cold rainy winters.This is an agrarian region,mostly with orchards of various fruit trees.This study investigated the physico-chemical properties and macrofauna of soils under various agricultural management practices of this region.The concentrations of soil organic matter(SOM),soil organic carbon(SOC),nutrients,pH,electrical conductivity,soil texture,and the abundance and number of species of soil macrofauna of the agricultural fields were measured.Fifteen agricultural fields were sampled.Fourteen fields were orchards of apple,apricot or the mixture of apple and apricot trees and one field was a cropland,cultivated with wheat as a monocrop.The orchards were under conservation agricultural practices;whereas,the cropland was under conventional management.These agricultural lands were 2-26 years old.The concentration of soil organic matter(SOM)in the upper 0-10 cm depth of these field sites ranged from 11.6 g kg^(-1)to 32.8 g kg^(-1)soil.As compared to cropland,orchards had significantly higher concentration of SOM and SOC.A total of 18 soil macrofauna species were found and the most common and abundant were ants(Monomorium minimum,Camponotus pennsylvanicus,Solenopsis invicta,and Lasius niger)followed by Arion ssp.(Brown Slug)and earthworm Lumbricus terrestris.Regression analysis revealed non-significant relationship of the age and the concentration of SOM with the number of macrofauna species and with the concentrations of total mineral nitrogen,bioavailable phosphorus and clay.The existence of ants had no relationship with the concentration of SOM;whereas,existence of Lumbricus terrestris tended to had a positive relationship with the concentration of SOM.The field of tree-based intercropping system was 2 years of age since the land was converted from rangeland to a cropland,had two ant species coexisting.This indicates the positive influence of crop diversification on soil macrofauna.

Soil erosion on the Brazilian sugarcane cropping system:An overview

Sugarcane(Saccharum officinarum)is an important crop for generating fiber,biofuel and other bioproducts.Brazil is the largest sugarcane producer in the world;however,limited knowledge is available with respect to soil erosion in the sugarcane cropping system.This study reviews the soil erosion rates in sugarcane cropping and evaluates the effects of soil management and land conversion on soil erosion.Eighteen studies(using conventional tillage)reporting 43 outcomes of soil erosion rates were examined using the Scopus®database.Different methods were used to measure soil erosion yielded different soil loss rates;highest values were recorded in the natural rain method,i.e.,experimental plots with a median of 28 Mg ha^(−1)yr^(−1),were obtained followed by modeling with 9.3 Mg ha^(−1)yr^(−1)and simulated rain with 2 Mg ha^(−1)yr^(−1).The median soil loss using all data(n=43)obtained by the three methods was 7.2 Mg ha^(−1)yr^(−1).The soil type increases soil erosion;the sugarcane cropping system is practiced over the most erodible Brazilian soils(e.g.,Ultisols and Oxisols)where sand fraction is dominant,particularly fine sand.Most studies focused on rainsplash and interrill erosion.However,rill,ephemeral and permanent gullies should be examined,particularly in sugarcane-cropping areas.

Improved crop protection and biodiversity of the agroecosystem by reduced tillage in rice paddy ffelds in southern China

Agricultural sustainability has benefited from the broad adoption of conservation agriculture(CA)practices for decades,in which the reduction of mechanical disturbances to soil(also known as reduced tillage,RT)is one of the most essential principles for CA implementation.Many studies have recommended the advantages of CA practices in the promotion of biodiversity,but the integrated impacts on crop productivity and biodiversity remain unclear.Since CA has been applied in rice production in the subtropical area of southern China for several years,the effects of CA,particularly the RT methods,need to be evaluated for the local and long-term adoption.In this study,we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates(such as rice pests and their predators),pathogens and weeds,and then led to an impact on rice yield.The two-year study demonstrated that major rice pests,such as rice planthoppers,stem borers and apple snails,were effectively controlled by RT practice.Similarly,the occurrence of common diseases declined with less tillage.Compared to the conventional tillage(CT)treatment,the density of weeds in paddy fields deceased significantly in the RT treatment.In addition,the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied,which highlighted the significance of a CA strategy for the promotion of biodiversity in the agroecosystem.More importantly,the rice yield gradually increased after the two-year reduction of tillage.Taken together,our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests,and facilitates the sustainability of the agroecosystem and rice yield,which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.

The transformation of agriculture in Argentina through soil conservation

The adoption of no till was a major turning point in the transformation of agriculture in Argentina.This paper describes the process of adoption of no till,and the impacts of this on agricultural production.Whereas previously,soil erosion was so extreme and pervasive as to threaten the economic viability and survival of the industry,today with the majority of production under no till,Argentina produces more than ever in the past.The paper also illustrates how,after first focusing on technology adoption(no-till),the system in Argentina has now broadened to include the concepts of Conservation Agriculture(CA)and Sustainable Land Management(SLM).These strategic moves have contributed to an agricultural industry in Argentina that is more economically and environmentally sustainable than that of the past.

Economic Evaluation of the Resource-Saving Technologies in Non-irrigated Lands

Conservation agriculture （CA） is especially relevant for Uzbekistan＇s agriculture, particularly in non-irrigated lands where soil fertility has been steadily declining and the risk of crop failure has been growing. CA has three main characterizations given in scientific literature, which are the minimal soil disturbance, crop rotation and surface crop residue retention. Nowadays, the majority of farmers are not widely using CA in their agricultural practices in Uzbekistan. Maybe, this is due to different perception of the economic efficiency of CA. The objective of the research was to calculate economic efficiency of CA in non-irrigated lands and to show whether it is effective or not in agricultural production. To achieve this objective, literature review including a variety of secondary data is employed. Overall, the costs of labor and fuel consumption per ha at CA technology are less in comparison with conventional technology. Using CA practices gives a chance to increase labour productivity, to use resource effectively and to improve soil quality and crop diversification.

Suppression of weeds and weed seeds in the soil by stubbles and no-tillage in an arid maize-winter wheat-common vetch rotation on the Loess Plateau of China

Reduced tillage provides ecological and economic benefits to arable land on the Loess Plateau of China, where soil erosion has long been a serious problem and soil water availability is largely restricted. However, high abundances of weeds in reduced tillage systems cause significant yield losses. In this study, we explored the effects of no-tillage and stubble retention on the number and density of weeds and weed seeds in a 12-year maize-winter wheat-common vetch rotation on the Loess Plateau. Four treatments including conventional tillage, no-tillage, conventional tillage＋stubble retention and no-tillage＋stubble retention were designed and applied. We found that no-tillage increased the number of weed species and weed density in most of the crops, while stubble retention decreased weed density in maize and tended to suppress weeds in both no-tillage treatments（no-tillage and no-tillage＋stubble retention）. No-tillage led to an increase in the number of weed species in the weed seedbank and tended to increase seed density during the spring growth of winter wheat, but it decreased seed density during post-vetch fallow. Stubble retention tended to reduce seed density during the spring growth of winter wheat and post-vetch fallow. We concluded that no-tillage can promote weeds in the experimental crop rotation, while stubble retention suppresses weeds in untilled fields. The combined effects of stubble retention and no-tillage on weed suppression varied among the three crops. Based on these results, we recommend stubble retention in untilled legume-crop rotations on the Loess Plateau to improve the control of weeds.