Marion Casagrande

Agroecological practices for sustainable agriculture. A review

The forecasted 9.1 billion population in 2050 will require an increase in food production for an additional two billion people. There is thus an active debate on new farming practices that could produce more food in a sustainable way. Here, we list agroecological cropping practices in temperate areas. We classify practices according to efficiency, substitution, and redesign. We analyse their advantages and drawbacks with emphasis on diversification. We evaluate the potential use of the practices for future agriculture. Our major findings are: (1) we distinguish 15 categories of agroecological practices (7 practices involve increasing efficiency or substitution, and 8 practices need a redesign often based on diversification). (2) The following agroecological practices are so far poorly integrated in actual agriculture: biofertilisers; natural pesticides; crop choice and rotations; intercropping and relay intercropping; agroforestry with timber, fruit, or nut trees; allelopathic plants; direct seeding into living cover crops or mulch; and integration of semi-natural landscape elements at field and farm or their management at landscape scale. These agroecological practices have only a moderate potential to be broadly implemented in the next decade. (3) By contrast, the following practices are already well integrated: organic fertilisation, split fertilisation, reduced tillage, drip irrigation, biological pest control, and cultivar choice.

How organic farmers practice conservation agriculture in Europe

The interest of organic farmers in adopting conservation agriculture principles, including minimal soil disturbance, permanent soil cover and crop rotation has been growing since the early 2000s. However, currently there is no network for organic farmers practicing conservation agriculture, and a lack of knowledge on how organic farmers implement conservation agriculture in practice. Consequently, few technical references are available for organic farmers when they start applying conservation agriculture practices, in particular on controlling weeds without the use of herbicides. The main objectives of this study were: (1) to explore the diversity of conservation agriculture techniques (i.e., reduced tillage, no-tillage and green manures) practiced among European farmers, and (2) to identify farmers’ main strategies for implementing conservation agriculture and the agronomic and environmental factors that determine these strategies. Strategies were identified by analyzing survey results on: (1) the type and degree of use of conservation agriculture practices by farmers, and (2) the effects it produces in terms of soil disturbance and soil cover (low, medium and high). We carried out a survey of 159 European organic farmers and collected 125 data sets on management of winter-sown crops. Among the conservation agriculture practices, reduced tillage was used by 89%, no-tillage by 27% and green manure by 74% of the 159 interviewed farmers. Green manures were more frequently used in northern Europe than in the south (below 45°N). Most of the farmers used crop rotations, with a mean duration of 6 years. A wide diversity of conservation agriculture practices were used, with farmers rarely using all three techniques (no-till, reduced till and green manures) within one system. The range of practices was grouped into five strategies ranging from intensive non-inversion tillage without soil cover to very innovative techniques with no-tillage and intercrops. The five strategies for conservation agriculture could be grouped into two larger categories based on weed control approach: (1) intensification of the mechanical work without soil inversion or (2) biological regulation of weeds with cover crops. The diversity of strategies identified in this study shows that organic farmers use innovative approaches to implement conservation agriculture without herbicides. This studys findings will help organic farmers to experiment with innovative practices based on conservation agriculture principles and also benefit conventional farmers who use conservation agriculture practices and would like to reduce or eliminate the use of herbicides.

Organic farmers’ motivations and challenges for adopting conservation agriculture in Europe

Conservation agriculture and organic farming are considered as promising sustainable agricultural system for producing food, while minimizing environmental impacts. Despite an increasing number of experimental data on organic conservation practices and various studies dealing with the adoption of conservation agriculture by farmers, none of those studies have specifically addressed conservation agriculture adoption under organic conditions in Europe. We carried out a survey with 159 farmers located in 10 European countries. These farmers had applied at least two of the following conservation practices: (i) no-tillage, (ii) reduced tillage and (iii) green manures. Each farmer assessed socio-economic, agronomic and environmental motivations and problems for each conservation practice, using a Likert scale. For each conservation practice, we ranked motivations and problems and carried out a principal component analysis, followed by clustering to identify groups of farmers. Independent of the conservation practices, the most important motivations were related to soil fertility preservation and challenges were mainly linked to crop management, machinery and yield performances. For all conservation practices, we identify three groups of farmers that shared the same type of motivations and challenges across Europe: “soil conservationists,” “agro-technically challenged farmers,” and “indifferent farmers.” Soil conservationist farmers were strongly motivated by soil preservation and minimizing environmental impacts. Agro-technically challenged farmers mainly expressed agronomic problems and challenges. There were no clear effects of location or farm characteristics explaining these attitudes, but they depended on farmers’ environmental concerns and beliefs. The study demonstrated that research priorities should address agronomic problems caused by the adoption of conservation practices in organic farming, weed control in particular.

Enhancing planned and associated biodiversity in French farming systems

In a context of global change involving uncertainty in agricultural production, agroecological systems need to reduce their dependency on inputs and increase their resilience. Biodiversity-based techniques are promising, as they provide production services based on biological processes. Tracking farmer practices is an original approach aiming at identifying and analysing alternative systems and supporting the development of these techniques. We studied, for the first time, the on-farm implementation of six biodiversity-based techniques: (i) agroecological infrastructures, (ii) cropped varietal mixtures, (iii) agroforestry, (iv) intercropping, (v) cover cropping and (vi) crop rotation diversification. We first analysed the combinations of these techniques in a large sample of 194 French farmers. A multiple correspondence analysis followed by a hierarchical cluster analysis on principal components resulted in groups of farms with different combinations of these techniques. Then, deeper interviews were conducted with 29 farmers across three regions to analyse the various methods of applying the techniques in the context of their farm and to identify the conditions for their successful implementation. Taking advantage of this large and rare sample of almost 200 interviewed farmers, we identified six different groups of farms. From farms applying mainly cover cropping to comply with European regulations to much diversified farms implying the redesign of the farming system, we support the idea that different strategies of implementation of such biodiversity-based techniques co-exist. The in-depth interviews demonstrated that the level of diversification is related to farm characteristics and four factors mainly favoured the development of such techniques on farms: (1) available labour force and (2) specialised machinery (internal factors) as well as (3) access to market opportunities and (4) the exchange of knowledge through networking (external factors). Surprisingly, the conservation agriculture farmers of our sample did not apply significantly more biodiversity-based techniques. However, our results indicated that organic farmers applied significantly more of these techniques. Our results suggest that enhancing knowledge exchange through networks would favour the broader application of such techniques. It could also be relevant to gather farmers, industries and public authorities to favour the emergence of market opportunities.

Organic farmers in Europe: motivations and problems for using conservation agriculture practices

The interest of organic farmers for adopting conservation agriculture practices is currently growing. But, there are few technical and scientific references available for organic farmers when they start applying conservation agriculture practices. The main objectives of this study are (1) to explore the diversity of crop management practices using conservation agriculture methods among European farmers, and (2) to identify main farmers’ strategies. We carried out a survey of 159 farmers located in 10 European countries. Data were analysis to identify groups of farmers that share the same type of spring and winter crop managements. Organic farmers in Europe show very diverse crop management. The high diversity of crop management can be described by two main strategies: ‘low soil cover’ and ‘soil conservation’ strategy. Distinct geographical distribution of both strategies suggests that applicability of conservation agriculture practices is strongly context oriented.Conserving and improving the fertility and quality of the limited soil resource to produce food, feed and fibre has always been the key to organic farmers’ management practices. This issue is also addressed in conservation agriculture systems that give up on soil tillage (no-tillage) or reduce tillage intensity, but often build on the extensive use of herbicides and mineral fertilizers. Both systems show advantages for soil quality (Holland, 2004; Mader et al., 2002) and therefore their combination is promising and may provide better soil quality. Challenges of introducing noor reduced tillage systems into organic farming are increased weed pressure, retarded mineralization of nutrients that both may lead to reduced crop yield (Peigne et al., 2007). Pioneer farmers have developed solutions and new machinery to be applicable in organic farming systems. Comparisons of reduced tillage to the traditional plough system have started on farms and systematic research started a decade ago. It was the aim of our research activities, accomplished within the frame of the European network TILMAN-ORG (www.tilman-org.net), to evaluate changes in soil carbon stocks and biological soil fertility parameters in soils from European field trials that compared reduced primary soil tillage options with standard procedures (mainly plough). The selected sites represent a geoclimatic gradient from the North-East to the South-West. The hypothesis was that reduced tillage is enhancing the stratification of soil organic matter, soil microbial biomass and activity, and is changing microbial community structure and microbial functions.Conservation agriculture and organic farming are currently considered as environmentally friendly options for producing food. This study explores the motivations and problems of organic European farmers that apply at least two conservation techniques: (i) no-tillage, (ii) reduced tillage and/or (iii) green manure. We carried out a survey with 159 farmers located in 10 European countries. Data were analysed with a principal component analysis followed by clustering to identify groups of farmers with similar motivations and problems. The most important motivations are related to soil preservation and problems are mainly linked to agronomic conditions and crop management. There are three groups of farmers that share the same type of attitude: “atypical farmers”, “soil conservationists” and “agro-technically challenged farmers”. Further research may address in priority agronomic problems, such as weed infestation, caused by adoption of conservation agriculture in organic agriculture.Environmental concerns are pushing organic farmers to substitute ploughing with reduced tillage but weed management under reduced tillage can be troublesome. One objective of the TILMAN-ORG Project is to improve weed management with reduced tillage ± cover crops without reducing weed community diversity. This paper reports results obtained in 2012 in 13 long-, mid-, and short-term trials scattered across Europe including winter cereals, maize, grain pea, potato, sunflower and grass/clover or legume leys. Longand midterm experiments showed higher weed abundance under reduced tillage but usually without reduced crop yield. Short-term trials showed that reduced tillage system may be troublesome to manage right after the conversion from ploughing, due to higher abundance of weeds and volunteer crops and reduced yield. Interestingly, there was no overall consistent relationship between weed diversity, always higher under reduced tillage, and crop yield.

Diversity of Conservation Agriculture Practices Among European Organic farmers

The interest of organic farmers for adopting conservation agriculture practices is currently growing. But, there are few technical and scientific references available for organic farmers when they start applying conservation agriculture practices. The main objectives of this study are (1) to explore the diversity of crop management practices using conservation agriculture methods among European farmers, and (2) to identify main farmers’ strategies. We carried out a survey of 159 farmers located in 10 European countries. Data were analysis to identify groups of farmers that share the same type of spring and winter crop managements. Organic farmers in Europe show very diverse crop management. The high diversity of crop management can be described by two main strategies: ‘low soil cover’ and ‘soil conservation’ strategy. Distinct geographical distribution of both strategies suggests that applicability of conservation agriculture practices is strongly context oriented.Conserving and improving the fertility and quality of the limited soil resource to produce food, feed and fibre has always been the key to organic farmers’ management practices. This issue is also addressed in conservation agriculture systems that give up on soil tillage (no-tillage) or reduce tillage intensity, but often build on the extensive use of herbicides and mineral fertilizers. Both systems show advantages for soil quality (Holland, 2004; Mader et al., 2002) and therefore their combination is promising and may provide better soil quality. Challenges of introducing noor reduced tillage systems into organic farming are increased weed pressure, retarded mineralization of nutrients that both may lead to reduced crop yield (Peigne et al., 2007). Pioneer farmers have developed solutions and new machinery to be applicable in organic farming systems. Comparisons of reduced tillage to the traditional plough system have started on farms and systematic research started a decade ago. It was the aim of our research activities, accomplished within the frame of the European network TILMAN-ORG (www.tilman-org.net), to evaluate changes in soil carbon stocks and biological soil fertility parameters in soils from European field trials that compared reduced primary soil tillage options with standard procedures (mainly plough). The selected sites represent a geoclimatic gradient from the North-East to the South-West. The hypothesis was that reduced tillage is enhancing the stratification of soil organic matter, soil microbial biomass and activity, and is changing microbial community structure and microbial functions.Conservation agriculture and organic farming are currently considered as environmentally friendly options for producing food. This study explores the motivations and problems of organic European farmers that apply at least two conservation techniques: (i) no-tillage, (ii) reduced tillage and/or (iii) green manure. We carried out a survey with 159 farmers located in 10 European countries. Data were analysed with a principal component analysis followed by clustering to identify groups of farmers with similar motivations and problems. The most important motivations are related to soil preservation and problems are mainly linked to agronomic conditions and crop management. There are three groups of farmers that share the same type of attitude: “atypical farmers”, “soil conservationists” and “agro-technically challenged farmers”. Further research may address in priority agronomic problems, such as weed infestation, caused by adoption of conservation agriculture in organic agriculture.Environmental concerns are pushing organic farmers to substitute ploughing with reduced tillage but weed management under reduced tillage can be troublesome. One objective of the TILMAN-ORG Project is to improve weed management with reduced tillage ± cover crops without reducing weed community diversity. This paper reports results obtained in 2012 in 13 long-, mid-, and short-term trials scattered across Europe including winter cereals, maize, grain pea, potato, sunflower and grass/clover or legume leys. Longand midterm experiments showed higher weed abundance under reduced tillage but usually without reduced crop yield. Short-term trials showed that reduced tillage system may be troublesome to manage right after the conversion from ploughing, due to higher abundance of weeds and volunteer crops and reduced yield. Interestingly, there was no overall consistent relationship between weed diversity, always higher under reduced tillage, and crop yield.