Posts Tagged ‘Conservation agriculture’

Medium-term effects of conservation agriculture based cropping systems for sustainable soil and water management and crop productivity in the Ethiopian highlands

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 132 (1): 53-62, 2012

Tesfay Araya, Wim M. Cornelis, Jan Nyssen, Bram Govaerts, Fekadu Getnet, Hans Bauer, Kassa Amare, Dirk Raes, Mitiku Haile, Jozef Deckers

In the northern Ethiopian highlands, croplands yield extremely high volumes of storm runoff and are the major contributor to sediment load in the rivers. A medium-term tillage experiment was carried out (2005–2010) on a Vertisol to quantify changes in runoff, soil loss and crop yield due to Conservation agriculture (CA) in the sub-humid May Zegzeg catchment. A randomized complete block design with 3 replications on permanent plots of 5 m by 14 m was used for three tillage treatments, (i) derdero+ (DER+), permanent raised beds with 30% standing crop residue retention and no-tillage on the top of the bed, (ii) terwah+ (TER+), ploughed once at sowing with 30% standing crop residue retention and furrows made at 1.5 m interval, and (iii) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues. Tillage operations in the three treatments were done using the local ard plough mahresha. Local crop rotation practices followed during the six years sequentially from the first to the sixth year included wheat-grass pea-wheat-hanfets (wheat and barley sown together)-grass pea-wheat. Glyphosate was sprayed starting from the third year (2007) at 2 L/ha before planting to control pre-emergent weed in DER+ and TER+. Runoff and soil loss were measured in collector trenches at the lower end of each plot. Soil organic matter was determined at two depths (0–15 cm) and (15–30 cm). Local farmers evaluated crop stands. Significantly different (p < 0.05) 4-yr mean soil losses of 14, 17 and 26 t/ha, 5-yr mean runoff depth of 76, 95 and 118 mm, and 5-yr runoff coefficient of 19, 24 and 30% were recorded for DER+, TER+ and CT, respectively. Soil organic matter was significantly higher in DER+ and TER+ compared to CT. The mean farmers’ evaluation of crop performance in the last three years (2008–2010) showed a significant higher score for DER+ (6/8) followed by TER+ (5.6) and least for CT (4.8/8), and improvements in crop yield were observed; however, a period of at least five years of cropping was required before the difference became significant. In addition to the positive effects on runoff, soil loss and crop yield, we argue that avoiding repeated tillage which is 10–11 oxen-span days per ha and the faster ploughing pace at sowing in DER+ will enable a reduction in oxen density with further natural resource benefits. DER + and TER+ are improvements to good local practices that qualify them as CA: we recommend large scale dissemination and implementation on Vertisols.


 

Global warming potential of agricultural systems with contrasting tillage and residue management in the central highlands of Mexico

Posted by Carelia Juarez on , in Journal Articles

Published in Agriculture, Ecosystems & Environment 152(1): 50-58, 2012

Luc Dendooven, Leonardo Patiño-Zúñiga, Nele Verhulst, Marco Luna-Guido, Rodolfo Marsch, Bram Govaerts

Conservation agriculture based on (1) minimal soil movement, (2) retention of rational amounts of crop residue, (3) economically viable crop rotations restores soil fertility. Conservation agriculture improves soil characteristics, but it remains to be seen how zero tillage (ZT) affected greenhouse gas emissions (GHG) and the global warming potential (GWP) compared to conventional tillage (CT) when crop residue was kept or removed in a maize-wheat crop rotation since 1991. The soil organic C content in the 0–60 cm layer was larger in ZT (117.7 Mg C ha−1) compared to CT (76.8 Mg C ha−1) when residue was retained, but similar when it was removed. Tillage and residue management had only a small effect on GWP of the GHG emissions. However, the C sequestered in the 0–60 cm was affected by tillage and crop residue management, resulting in a negative net GWP for ZT with crop residue retention (−6.277 Mg CO2 ha−1 y−1) whereas in the other management practices it ranged from 1.288 to 1.885 Mg CO2 ha−1 y−1. It was found that cultivation technique had little effect on the GWP of the GHG, but had a large effect on C sequestered in the 0–60 cm layer and the net GWP.

 

Failing to yield? ploughs, conservation agriculture and the problem of agricultural intensification: an example from the Zambezi Valley, Zimbabwe

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Development Studies 48(3): 393-412, 2012

Frédéric Baudron, Jens A. Andersson, Marc Corbeels and Ken E. Giller

Agricultural intensification, or increasing yield, has been a persistent theme in policy interventions in African smallholder agriculture. This article focuses on two hegemonic policy models of such intensification: (1) the ‘Alvord model’ of plough-based, integrated crop-livestock farming promoted in colonial Zimbabwe; and (2) minimum-tillage mulch-based, Conservation Agriculture, as currently preached by a wide range of international agricultural research and development agencies. An analysis of smallholder farming practices in Zimbabwe’s Zambezi Valley, reveals the limited inherent understanding of farmer practices in these models. It shows why many smallholder farmers in southern Africa are predisposed towards extensification rather than intensification, and suggests that widespread Conservation Agriculture adoption is unlikely.

Conservation Agriculture in Maize- and Wheat-Based Systems in the (Sub)tropics: Lessons from Adaptation Initiatives in South Asia, Mexico, and Southern Africa

Posted by Carelia Juarez on , in Journal Articles

Published in  Journal of Sustainable Agriculture 36(2): 180-206, 2012

Olaf Erenstein, Ken Sayre, Patrick Wall, Jon Hellin and  John Dixon

Conservation agriculture’s underlying principles—minimal soil disturbance, soil cover and crop rotation—are increasingly recognized as essential for sustainable agriculture. This article summarizes three contrasting cases of adapting conservation agriculture (CA) to smallholder conditions in the (sub) tropics: a) irrigated rice-wheat systems in South Asia; b) rainfed maize/wheat and irrigated wheat systems in Mexico; and c) rainfed maize in Southern Africa. In the South Asia case, farm surveys show rapid and widespread adoption of zero tillage wheat—primarily due to a substantial cost saving (15–16%). In the other cases, uptake so far has been limited—although long-term trials show continuously higher and more stable yields both for maize and wheat. Under marginal conditions CA can generate substantial yield increases—averaging some 50% over conventional smallholder maize yields of 1 ton per ha over 6 years in on-farm trails in Southern Africa. The diverse experiences attest to the wide adaptability of CA systems, which can generate clear economic and potentially enormous environmental benefits. The case studies and wider literature however also reiterate the substantial challenges in terms of targeting, adapting and adopting CA—particularly for smallholders in the (sub)tropics. CA systems are best developed in situ through a multi-stakeholder adaptive learning process to create viable CA-based options that are technically sound, economically attractive, and socially acceptable.

 

The use of the marasha ard plough for conservation agriculture in Northern Ethiopia

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Published in Agronomy for Sustainable Development 31(287-297), 2011

The use of the marasha ard plough for conservation agriculture in Northern Ethiopia

Jan Nyssen, Bram Govaerts, Tesfay Araya, Wim M. Cornelis, Hans Bauer, Mitiku Haile5, Ken Sayre and Jozef Deckers

Indigenous tillage systems are often undervalued in conservation agriculture (CA). In Ethiopia, since the 1970s there have been several attempts to develop and implement often major modifications to the marasha, the traditional ox-drawn ard plough, with the main aim of creating various types of surface depressions. The establishment of furrows and ridges increases soil moisture and grain yield and reduces soil loss. Dissemination of the modified tools, however, remains limited. Recent tendencies are towards testing relatively simple conservation agriculture tools. Major challenges remain, however; the need for capacity building and problems in marketing the tools. From experimental plots, often worked with exotic tools, there is a long road to real adoption by farmers. Rather than developing yet another CA tool, we investigate whether CA-based resource-conserving technologies might be achieved successfully with simple changes to the use of the marasha. On-farm observations on traditional conservation techniques were carried out throughout the northern Ethiopian highlands, and experiments were conducted involving resource-conserving technologies. Farmers traditionally use the marasha ard plough for various types of in situ soil and water conservation by creating surface depressions, either at the moment of sowing (terwah, derdero) or after crop emergence (shilshalo). Building upon this indigenous knowledge, we further developed resource-conserving technologies into a system named derdero+, whereby the traditional ard plough was found suitable for a “bed-and-furrow” system. From the socio-economic point of view, implementation of permanent beds and retention of stubble leads to decreased oxen (and straw) requirements, but also to an increased need for weeding in the first years. To overcome that problem, we introduced glyphosate herbicide into the tillage system. The decreased runoff (–51%) and soil loss (–81%) allow protection of the downslope areas from flooding, but soil nutrient build-up and soil structure improvement are slow processes, and hence the full benefit of the permanent bed system can only be expected after some years. Overall, this type of resource-conserving technology can be part of the ongoing intensification process which includes physical soil and water conservation, slope reforestation and irrigation development. It has, however, its own niche: the cropped land sensu stricto, i.e. the most important part of the land, both for the farmer and for a nation that is striving for long-term food security.

Effects of conservation agriculture on runoff, soil loss and crop yield under rainfed conditions in Tigray, Northern Ethiopia

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Published in Soil Use and Management 27(3): 404-414, 2011

Effects of conservation agriculture on runoff, soil loss and crop yield under rainfed conditions in Tigray, Northern Ethiopia

Tesfay Araya, W. M. Cornelis, J. Nyssen, B. Govaerts, H. Bauer, Tewodros Gebreegziabher, Tigist Oicha, D. Raes, K. D. Sayre, Mitiku Haile and J. Deckers

The aim of conservation agriculture (CA) is to improve soil quality and crop yield whilst reducing runoff and topsoil erosion. An experiment was carried out in a rainfed field using a permanent raised bed planting system for 3 yr (2005–2007) in Adigudem, northern Ethiopia in order to evaluate the effect of CA on runoff, soil loss and crop yield. CA practices were introduced in fields with Vertisols in a randomized complete block design on permanent 5 × 19 m plots. Three treatments were evaluated: (1) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues, (2) terwah (TER) that was similar to CT except that contour furrows were included at 1.5 m intervals, and (3) derdero+ (DER+), which consists of permanent raised beds with a furrow and bed system, retention of 30% of standing crop residues and zero tillage on the top of the bed. All ploughing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plough called maresha. Results from monitoring over 3 yr showed that soil loss and runoff were significantly higher (< 0.05) in CT followed by TER and DER+. Average soil losses of 5.2, 20.1 and 24.2 t/ha were recorded from DER+, TER and CT, respectively. Runoff was 46.3, 76.3 and 98.1 mm from DER+, TER and CT, respectively. Grain yield was significantly lower (< 0.05) in DER+ under teff in 2006, probably due to the high sensitivity of teff to weeds. The yield of wheat in 2007 was significantly higher in DER+ followed by TER. The terwah system is recommended as a first measure for wider adoption to reduce runoff and soil loss and to increase crop yield. The long-term goal is to achieve a derdero+ system, i.e. a permanent raised bed planting system along with the application of crop residues.

Wheat yield and tillage–straw management system × year interaction explained by climatic co-variables for an irrigated bed planting system in northwestern Mexico

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Published in Field Crops Research 124(3): 347-356, 2011

Wheat yield and tillage–straw management system × year interaction explained by climatic co-variables for an irrigated bed planting system in northwestern Mexico

Nele Verhulst, Ken D. Sayre, Mateo Vargas, Jose Crossa, Jozef Deckers, Dirk Raes, Bram Govaerts

Wheat is an important food and income source and estimated demand for wheat in the developing world is projected to increase substantially. The objectives of this study were to gain insight into (i) the effect of tillage–straw system on yield and yield components (number of grains per m2 and thousand kernel weight), (ii) the relation between climatic conditions and yield and yield components, (iii) the explanation of tillage–straw system × year interaction for yield and yield components by climatic co-variables. Wheat grain yield and yield components were measured in a long-term trial established in 1992 under irrigated, arid conditions in northwestern Mexico. Five tillage–straw management systems (conventionally tilled raised beds [CTB] with straw incorporated and permanent raised beds [PB] with straw burned, removed, partly retained or fully retained) were compared for a wheat–maize rotation. Daily climatic data were averaged over six periods corresponding approximately to advancing wheat growth stages. The PB-straw retained and PB-straw removed had the highest yields (average yield of 7.31 and 7.24 t ha−1, respectively) and grains per m2. The PB-straw burned had the lowest yield (average yield of 6.65 t ha−1) and grains per m2, but the highest thousand kernel weight. Maximum temperature was positively correlated to final grain yield during tillering and head differentiation, but was negatively correlated to thousand kernel weight during grain-filling. For the tillage–straw system year interaction, three groups of management systems were distinguished for yield and grains per m2: PB-straw burned, CTB-straw incorporated and PB where straw is not burned. The CTB-straw incorporated had a positive interaction with year in favorable years with high radiation and evapotranspiration. The PB-straw burned was relatively more affected by excess water conditions and showed positive interactions in years with high relative humidity. The PB-straw retained was the most stable in different climatic conditions, indicating that this management system could contribute to maintaining wheat yield in a changing climate scenario.

 

Soil water content, maize yield and its stability as affected by tillage and crop residue management in rainfed semi-arid highlands

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Published in Plant and Soil, 344(1-2):73-85, 2011

Soil water content, maize yield and its stability as affected by tillage and crop residue management in rainfed semi-arid highlands

Nele Verhulst, Victoria Nelissen, Niels Jespers, Heleen Haven, Ken D. Sayre, Dirk Raes, Jozef Deckers and Bram Govaerts

Rainfed crop management systems need to be optimized to provide more resilient options to cope with projected climatic scenarios forecasting a decrease in mean precipitation and more frequent extreme drought periods in Mexico. Soil water content (0–60 cm) was measured during three crop cycles in maize plots with different agronomic management practices in a long-term rainfed experiment (established in 1991) in the highlands of Mexico. Maize yields of 1997–2009 were reported. Crop management practices varied in (1) tillage (conventional [CT] vs. zero tillage [ZT]) and (2) residue management (full or partial retention and removal). ZT with residue retention had higher soil water content than management practices involving CT and ZT with residue removal which provided a buffer for drought periods during the growing seasons. In 2009, a cycle with a prolonged drought during vegetative growth, this resulted in yield differences of up to 4.7 Mg ha−1 between ZT with (partial) residue retention and the other practices. Averaged over 1997–2009, these practices had a yield advantage of approximately 1.5 Mg ha−1 over practices involving CT and ZT with residue removal. ZT with (partial) residue retention used rainfall more efficiently and resulted in a more resilient agronomic system than practices involving either CT or ZT with residue removal.

Cropping systems and crop residue management in the Trans-Gangetic Plains: Issues and challenges for conservation agriculture from village surveys

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Published in Agricultural Systems 104(1), 2011

Cropping systems and crop residue management in the Trans-Gangetic Plains: Issues and challenges for conservation agriculture from village surveys

Olaf Erenstein

Conservation agriculture practices are being advocated to help sustain crop productivity gains and secure environmental sustainability in the Trans-Gangetic Plains, India’s Green Revolution heartland. The paper illustrates the use of village surveys as a quasi-quantitative system analysis tool to derive implications for agricultural research and development. Drawing from village surveys in 170 communities, the paper assesses current crop residue management practices in Punjab and Haryana’s rice–wheat, basmati–wheat and non-rice–wheat cropping systems. The prevalence of wheat as the winter crop implies an intensive collection, trading and use of wheat straw as basal feed for dairy livestock; which contrasts with the diverse crop residue management of the monsoon crops. The increased use of combine harvesters has spurred the rapid advent of mechanical wheat straw reapers whereas the bulk of combine harvested rice straw is burned in situ. Present crop residue management practices are largely incompatible with year-round mulch retention despite significant biomass production. The research and development community faces the challenge of evening out straw use and management over seasons to ensure at least partial residue retention if its calls for conservation agriculture in this important sub-region are to succeed. The paper also reiterates the worrying decline of groundwater tables associated with the rice–wheat system

Effects of conservation agriculture techniques on infiltration and soil water content in Zambia and Zimbabwe

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Published in Soil and Tillage Research 105(2): 217-227

Effects of conservation agriculture techniques on infiltration and soil water content in Zambia and Zimbabwe

Christian Thierfelder, Patrick C Wall

The adoption of conservation agriculture (CA), based on minimal soil movement, permanent soil cover with crop residues or growing plants and crop rotation has advanced rapidly in the Americas and Australia over the last three decades. One of the immediate benefits of CA in dryland agriculture is improved rainfall-use efficiency through increased water infiltration and decreased evaporation from the soil surface, with associated decreases in runoff and soil erosion. This paper focuses on the effect of CA techniques on soil moisture relations in two researcher-managed trials in Zambia and Zimbabwe. In 2005/2006 and 2006/2007, we found significantly higher water infiltration on both sites on CA fields compared to conventionally ploughed fields. At Henderson Research Station, Zimbabwe, on a sandy soil, a direct seeded CA treatments had a 49% and 45% greater infiltration rate than the conventionally tilled plots after a simulated rainfall in both seasons. At Monze Farmer Training Centre, Zambia, on a finer-textured soil, the same treatment had 57% and 87% greater infiltration rate than the conventionally tilled control treatment in both seasons. Treatments that included reduced tillage and surface residue retention had less water runoff and erosion on runoff plots at Henderson Research Station, Zimbabwe. On average, soil moisture was higher throughout the season in most CA treatments than in the conventionally tilled plots. However, the full potential of CA in mitigating drought was not evident as there was no significant drought period in either season. Results suggest that CA has the potential to increase the productivity of rainfall water and therefore reduce the risk of crop failure, as was apparent at the Monze Farmer Training Centre, Zambia, in 2005/2006 when a period of moisture stress at tassling affected CA treatments less than the conventionally tilled treatment.