Global achievements in soil and water conservation: The case of Conservation Agriculture

AbstractIn response to the dust bowls of the mid-thirties in the USA, soil and water conservation programmes involving reduced tillage were promoted to control land degradation, particularly soil erosion. The farming and land management practices that were considered to adequately address soil and water conservation objectives were based on no-till seeding and maintenance of soil mulch cover. This collection of practices led to what became known as conservation tillage, although no-till systems by definition avoid soil disturbance by no-till direct seeding, and maintain an organic mulch cover on the soil surface.This article is an overview of achievements in soil and water conservation on agricultural lands through the experience derived from the adoption and spread of Conservation Agriculture (CA) world-wide. CA is an agro-ecological approach to sustainable production intensification. It involves the application of three inter-linked principles that underpin agricultural production systems based on locally formulated practices: (i) permanent no or minimum mechanical soil disturbance, which in practice entails direct seeding through mulch into no-till soils; (ii) maintenance of soil cover with crop residues and green manure crops, particularly legumes; and (iii) diversified cropping system involving annuals and perennial in rotations, sequences and associations.In 2011, CA had spread over 125 million hectares (9% of the global cropped land) across all continents and most agro-ecologies, including small and large farms. In addition, there is a significant area of CA orchards in the Mediterranean countries. CA is now considered to be a practical agro-ecological approach to achieving sustainable agriculture intensification. It offers environmental, economic and social advantages that are not fully possible with tillage-based production systems, as well as improved productivity and resilience, and improved ecosystem services while minimizing the excessive use of agrochemicals, energy and heavy machinery. While there are challenges to the adoption of CA, there is also increasing interest from producers, the civil society, donors and private sector institutions to further promote and service the uptake and spread of CA globally

Conservation agriculture in the dry Mediterranean climate

The objective of this article is to review: (a) the concepts and principles that underpin Conservation Agriculture (CA) ecologically and operationally; (b) the potential benefits that can be harnessed through CA systems in the dry Mediterranean climates; (c) current status of adoption and spread of CA in the dry Mediterranean climate countries; and (d) opportunities for CA in the Central and West Asia and North Africa (CWANA) region. CA, comprising minimum mechanical soil disturbance and no-tillage seeding, organic mulch cover, and crop diversification is now practised on some 125 million ha, corresponding to about 9% of the global arable cropped land. Globally, the area under CA is spread across all continents and all agro-ecologies, including the dryland climates in the Mediterranean basin region as well as in the Mediterranean climates elsewhere in the world. Worldwide empirical and scientific evidence is available to show that significant productivity, economic, social and environmental benefits exist that can be harnessed through the adoption of CA principles for sustainable production intensification in the dry Mediterranean climates, including those in the CWANA region. The benefits include: fundamental change for the better in the sustainability of production systems and ecosystem services; higher stable yields and incomes; climate change adaptation and reduced vulnerability to the highly erratic rainfall distribution; and reduced greenhouse gas emissions. CA has taken off globally and is now spreading in several Mediterranean climates outside the Mediterranean basin particularly in South America, South Africa and Australia. In the dry Mediterranean climates in the CWANA region, CA is perceived to be a powerful tool of land management but CA has not yet taken off. Research on CA in the CWANA region has shown that there are opportunities for CA adoption in rainfed and irrigated farming systems involving arable and perennial crops as well as livestock

Overview of the Worldwide Spread of Conservation Agriculture

The global empirical evidence shows that farmer-led transformation of agricultural production systems based on Conservation Agriculture (CA) principles is already occurring and gathering momentum globally as a new paradigm for the 21st century. The data presented in this paper has been collected by the Food and Agriculture Organization of the United Nations from several sources including estimates made by ministries of agriculture, by farmer organizations, and well-informed individuals in research or development organizations; they provide an overview of CA adoption and spread by country, as well as the extent of CA adoption by continent. CA systems, comprising no or minimum mechanical soil disturbance, organic mulch soil cover, and crop species diversification, in conjunction with other good practices of crop and production management, are now (in 2013) practiced globally on about 157 M ha, corresponding to about 11% of field cropland, in all continents and most land-based agricultural ecologies, including in the various temperate environments. This change constitutes a difference of some 47% globally since 2008/09 when the spread was recorded as 106 M ha. The current total of 157 M ha represents an increase in adoption of CA by more countries but the estimate is on the conservative side as the updated database does not capture all the CA cropland. While in 1973/74 CA systems covered only 2.8 M ha worldwide, the area had grown in 1999, to 45 M ha, and by 2003 the area had grown to 72 M ha. In the last 10 years CA cropland has expanded at an average rate of more than 8.3 M ha per year and since 2008/2009 at the rate of some 10 M ha per year, showing the increased interest of farmers and national governments in this alternate production concept and method. Adoption has been intense mainly in North and South America as well as in Australia and Asia, and more recently in Europe and Africa where the awareness of and support for CA is on the increase. The paper presents an update of the adoption of CA since 2008/09.Au vu des données empiriques mondiales, la transformation des systèmes de production agricole, qui s’appuient sur les principes de l’Agriculture de Conservation (AC), conduite par les agriculteurs eux-mêmes, est déjà engagée et s’impose peu à peu comme un nouveau modèle mondial pour le 21ème siècle. Les données de cet article ont été recueillies par l'Organisation des Nations Unies pour l’Alimentation et l’Agriculture (FAO) auprès de plusieurs sources et sont notamment issues d'études réalisées par des ministères de l'agriculture, des organisations d'agriculteurs et des experts d'organismes de recherche et développement ; elles donnent un aperçu par pays et par continent du niveau d’adoption et de progression de l’AC. Les pratiques de l’AC, qui englobent la perturbation mécanique minimale, voire aucune perturbation mécanique du sol, l’utilisation des paillis organiques et la diversification des espèces cultivées, associées à d’autres bonnes pratiques de gestion des cultures et de la production, sont aujourd’hui (en 2013) mises en œuvre sur près de 157 millions d’hectares, soit près de 11 % des terres cultivées, sur tous les continents et dans la plupart des écologies agricoles, notamment dans les divers environnements tempérés. Cette évolution représente un écart de près de 47 % au niveau mondial par rapport aux années 2008/09, où l'AC était pratiquée sur 106 millions d’hectares. Le chiffre actuel de 157 millions d’hectares reflète une adoption plus large de l'AC dans un nombre croissant de pays mais il s'agit là d'une estimation prudente, la base de données actualisée ne prenant pas en compte la totalité des terres cultivées en AC. Alors que l'AC couvrait seulement 2,8 M ha dans le monde en 1973/74, elle s'est étendue à 45 M ha en 1999 et 72 M ha en 2003. Au cours des dix dernières années, la surface de terres cultivées en AC s’est développée à un rythme moyen de plus de 8,3 M ha par an et d'environ 10 M ha par an depuis 2008/2009, illustrant l’intérêt croissant des agriculteurs et des gouvernements pour ce concept et ces méthodes de production alternatifs. L'adoption de l'AC a été particulièrement soutenue en Amérique du Nord et en Amérique du Sud, ainsi qu'en Australie et en Asie, et, plus récemment, en Europe et en Afrique, où la sensibilisation aux principes de l'AC et l’encouragement de leur adoption ne cessent d'augmenter. Cet article présente un état des lieux de l'adoption de l'AC depuis 2008/09.Las pruebas empíricas a nivel mundial muestran que la transformación de los sistemas de producción agrícola guiada por los agricultores y basada en los principios de la agricultura de conservación ya se está produciendo y está cobrando impulso en todo el mundo como un nuevo paradigma para el siglo XXI. Los datos presentados en este trabajo han sido obtenidos por la Organización de las Naciones Unidas para la Agricultura y la Alimentación de varias fuentes, entre las que se incluyen las estimaciones realizadas por ministerios de agricultura, organizaciones de agricultores y otros entendidos en la materia de organizaciones de investigación o desarrollo, y proporcionan una perspectiva general de la adopción y la propagación de la agricultura de conservación por país, así como el alcance de la adopción de la agricultura de conservación en los distintos continentes. Los sistemas de agricultura de conservación, que incluyen una perturbación mecánica mínima o nula de la tierra, el uso de una capa de mantillo natural y la diversificación de las especies de cultivo, en combinación con otras prácticas positivas de gestión de cultivos y de la producción, se utilizan actualmente (en 2013) a nivel mundial en unos 157 millones de hectáreas, lo que corresponde aproximadamente al 11 % de las tierras de cultivo, en todos los continentes y la mayoría de las agroecologías basadas en el suelo, incluidos los ambientes templados. Este cambio constituye una diferencia de aproximadamente el 47 % en todo el mundo desde los años 2008-2009 cuando la propagación era de 106 millones de hectáreas. La cifra total actual de 157 millones de hectáreas representa un aumento en la adopción de la agricultura de conservación por parte de más países si bien esta estimación es conservadora ya que la base de datos actualizada no abarca todas las tierras de cultivo en las que se practica la agricultura de conservación. Mientras en los años 1973-1974 los sistemas de agricultura de conservación ocupaban solo 2,8 millones de hectáreas en el mundo, esta extensión fue creciendo hasta alcanzar los 45 millones de hectáreas en 1999 y los 72 millones de hectáreas en 2003. En los últimos 10 años las tierras de cultivo en las que se practica la agricultura de conservación se han extendido a un ritmo medio de más de 8,3 millones de hectáreas por año y desde los años 2008-2009 a un ritmo de unos 10 millones de hectáreas por año, lo que demuestra el creciente interés de los agricultores y los gobiernos nacionales en este concepto y método de producción alternativa. La adopción ha sido especialmente importante en América del Norte y del Sur, así como en Australia y Asia, y más recientemente en Europa y África, donde la concienciación y el apoyo a la agricultura de conservación son cada vez mayores. Este trabajo presenta información actualizada sobre la adopción de la agricultura de conservación desde los años 2008-2009

Earthworm richness in no-till sites in Paraguay.

ISEE 10

Effects of Zero Tillage (No-Till) Conservation Agriculture on soil physical and biological properties and their contributions to sustainability.

Not cultivating soil, rotating crops over the years, and leaving crop residues on the surface in the practice of zero tillage/conservation agriculture (ZT/CA) reverses the historically accelerating degradation of soil organic matter (SOM) and soil structure, while increasing soil biological activity by a factor of 2 to 4. The results of this are many: (a) not cultivating reduces soil compaction, leaving old root holes to facilitate internal drainage, averts the pulverization of soil aggregates and formation of pans, reduces draft power for planting and gives shelter, winter food and nesting sites for fauna, (b) crop residues on the surface practically eliminate wind and water erosion, reduce soil moisture loss through the mulch effect, slow spring warm-up (possibly offset by a lower specific heat demand with less water retention in surface soil) and act as a reserve of organically-compounded nutrients (as they decompose to humus), (c) more SOM means higher available water and nutrient retention, higher biological activity year round (enhancing biological controls), higher levels of water-stable aggregates and a positive carbon sink in incremental SOM. The positive impacts for society are: (i) more and cheaper food, (ii) reduced flood and drought-induced famine risks, (iii) a positive carbon sink in SOM and possible reductions in NO emissions, (iv) cleaner water and greater aquifer recharge due to reduced runoff, (v) cleaner air through effective elimination of dust as a product of cultivation (vi) less water pollution and greater aquifer recharge from reduced rainfall runoff, (vii) farm diesel consumption halved, (viii) reduced demand for (tropical) de-forestation, by permitting crop expansion on steeper lands, (ix) increased wildlife populations (skylarks, plovers, partridge and peccaries) and (x) an improved conservation mindset in farmers. It is notable that, in spite of successful practitioners in all European countries, mainstream adoption is still to come: Europe s ZT/CA area is 1.35 million hectares, while the world area is now some 125 million and growing at a rate of 7 million hectares per year. More scientific measurements of the benefits of this system are required, both to assist adoption and to trigger policy measures. In the EEC, CAP reform (greening) needs to consider making environmental services payments for these social benefits since a reduction in single farm payments is ineluctable and carbon footprint reduction is of the essence, in the face of constantly-rising fuel prices and the need to cut GHG emissions. Therefore, as the principal farm tool which offers an effective and immediate solution towards positive changes in soil quality, productivity and sustainability, ZT/CA adoption needs financial incentives, which have high economic and environmental returns to society

Fitomassa de adubos verdes e controle de plantas daninhas em diferentes densidades populacionias de leguminosas.

O objetivo deste trabalho foi avaliar a fitomassa de calopogônio, mucuna-preta, mucunarajada,feijão-de-porco, guandu de porte alto, Crotalaria spectabilis e C. breviflora sob diferentes densidades de semeadura (10, 20, 40, 80 e 160 sementes viáveis m-2), e o crescimento de plantas daninhas nessas densidades, em área de tabuleiros costeiros. O experimento foi desenvolvido de maio a agosto de 1996, no Campo Experimental “Antônio Martins”(EMDAGRO/Embrapa-CPATC), em Lagarto, SE. O número de plantas vivas na floração (NPVF) e a matéria seca da parte aérea das leguminosas (MSPA) foram determinados quando, em cada espécie, cerca de 50% das plantas floresceram. Maiores incrementos de MSPA, em resposta ao adensamento populacional, foram observados em C. spectabilis e C. breviflora, seguidas pelo calopogônio, mucuna-preta e mucuna-rajada. Em relação ao feijão-de-porco, a resposta foi negativa, enquanto com o guandu não houve influência. Quanto ao NPVF, as respostas ao adensamento foram lineares e positivas em C. spectabilis, C. breviflora e calopogônio, e quadráticas com ponto de máxima em feijão-de-porco,guandu e mucuna-rajada. Embora nenhum modelo tenha sido ajustado para expressar a relação entre NPVF e adensamento na semeadura de mucuna-preta, a sobrevivência dessa espécie foi reduzida em todas as densidades. Maiores inibições de plantas daninhas ocorreram nas parcelas de mucuna-preta e feijão-de-porco

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact