Posts Tagged ‘No-tillage’

Conservation agriculture in southern Africa: advances in knowledge

Posted by Carelia Juarez on , in Journal Articles

Published in Renewable Agriculture and Food Systems, 2014

Thierfelder, C.; Rusinamhodzi, L.; Ngwira, A.R.;Mupangwa, W.; Isaiah, N.; Kassie, G.T.; Cairns, J.E.

The increasing demand for food from limited available land, in light of declining soil fertility and future threats of climate variability and change have increased the need for more sustainable crop management systems. Conservation agriculture (CA) is based on the three principles of minimum soil disturbance, surface crop residue retention and crop rotations, and is one of the available options. In Southern Africa, CA has been intensively promoted for more than a decade to combat declining soil fertility and to stabilize crop yields. The objective of this review is to summarize recent advances in knowledge about the benefits of CA and highlight constraints to its widespread adoption within Southern Africa. Research results from Southern Africa showed that CA generally increased water infiltration, reduced soil erosion and run-off, thereby increasing available soil moisture and deeper drainage. Physical, chemical and biological soil parameters were also improved under CA in the medium to long term. CA increased crop productivity and also reduced on-farm labor, especially when direct seeding techniques and herbicides were used. As with other cropping systems, CA has constraints at both the field and farm level. Challenges to adoption in Southern Africa include the retention of sufficient crop residues, crop rotations, weed control, pest and diseases, farmer perception and economic limitations, including poorly developed markets. It was concluded that CA is not a ‘one-size-fits-all’ solution and often needs significant adaptation and flexibility when implementing it across farming systems. However, CA may potentially reduce future soil fertility decline, the effects of seasonal dry-spells and may have a large impact on food security and farmers’ livelihoods if the challenges can be overcome.

Understanding the impact and adoption of conservation agriculture in Africa: A multi-scale analysis

Posted by Carelia Juarez on , in Journal Articles

Published in  Agriculture, Ecosystems and  Environment, 2013

Corbeels, M.; Graaff, Jan de; Ndah, T.H.; Penot, E.; Baudron, F.; Naudin, K.; Andrieu, N.; Chirat, G.; Schuler, J.; Nyagumbo, I.; Rusinamhodzi, L.;Traore, K.; Mzoba, H.D.; Adolwa, I.S.

Conservation agriculture (CA) is increasingly promoted in Africa as an alternative for coping with the need to increase food production on the basis of more sustainable farming practices. Success with adopting CA on farms in Africa has been limited, despite more than two decades of research and development investments. Through analyzing past and on-going CA experiences in a set of case studies, this paper seeks to better understand the reasons for the limited adoption of CA and to assess where, when and for whom CA works best. CA is analyzed and understood within a framework that distinguishes the following scales of analysis: field, farm, village and region. CA has a potential to increase crop yields in the fields, especially under conditions of erratic rainfall and over the long-term as a result of a gradual increase of overall soil quality. The impact on farm income with the practice of CA on some fields of the farm is far less evident, and depends on the type of farm. The lack of an immediate increase in farm income with CA explains in many cases the non-adoption of CA. Smallholders have often short-term time horizons: future benefits do not adequately outweigh their immediate needs. Another key factor that explains the limited CA adoption in mixed crop-livestock farming systems is the fact that crop harvest residues are preferably used as fodder for livestock, preventing their use as soil cover. Finally, in most case studies good markets for purchase of inputs and sale of produce – a key prerequisite condition for adoption of new technologies – were lacking. The case studies show clear evidence for the need to target end users (not all farmers are potential end user of CA) and adapt CA systems to the local circumstances of the farmers, considering in particular the farmer’s investment capacity in the practice of CA and the compatibility of CA with his/her production objectives and existing farming activities. The identification of situations where, when and for whom CA works will help future development agents to better target their investments with CA.

Intensification of conservation agriculture systems for increased livestock feed and maize production in Zimbabwe

Posted by Carelia Juarez on , in Journal Articles

Published in International Journal of Agricultural Sustainability, 2013

Mupangwa, W.; Thierfelder, C.

Livestock and crops are key components of mixed farming systems and are a source of household food and income. However, mixed farming systems face livestock feed shortages and low soil productivity challenges. Conservation agriculture (CA) systems based on minimum soil disturbance, crop residue retention and crop rotations offer an opportunity to grow both fodder and food crops on the available land to improve productivity and crop output per-unit area. A four-year experiment involving maize monocropping as control treatment and four relay or intercropping treatments with different legume and fodder crops was set up on contrasting soils in Zimbabwe. Lablab was superior in biomass production compared with radish on both soil types. On the clay soil, continuous maize, sole lablab, sole radish, maize/lablab relay and radish/common beans relay treatments produced similar biomass when soil moisture was adequate. When soil moisture was limiting, lablab produced more biomass than continuous maize, radish, maize/lablab relay and radish/beans relay treatments on clay soil. On sandy soils, lablab produced more biomass than continuous maize, radish, maize/lablab relay and radish/beans relay treatments. Leguminous and non-leguminous fodder crops can be grown successfully in CA systems that are being promoted in the mixed crop/livestock farming systems of southern Africa.

Precision nutrient management in conservation agriculture based wheat production of Northwest India: Profitability, nutrient use efficiency and environmental footprint

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research, 2013

Sapkota, T.B.; Majumdar, K.; Jat, M.L.; Kumar, A.; Bishnoi, D.K.;McDonald, A.J.; Pampolino, M.

In the high-yielding wheat production systems in Northwest (NW) Indo-Gangetic Plains of India, intensive tillage operations and blanket fertilizer recommendations have led to high production costs, decreased nutrient use efficiency, lower profits and significant environmental externalities. No-tillage (NT) has been increasingly adopted in this region to reduce costs and increase input use efficiency. But, optimal nutrient management practices for NT based wheat production are still poorly understood. Opportunities exist to further enhance the yield, profitability, and resource use efficiency of NT wheat through site-specific nutrient management (SSNM).

On-farm trials were conducted in seven districts of Haryana, India for two consecutive years (2010–11 and 2011–12) to evaluate three different approaches to SSNM based on recommendations from the Nutrient Expert® (NE) decision support system in NT and conventional tillage (CT) based wheat production systems. Performance of NE based recommendations was evaluated against current state recommendations and farmers’ practices for nutrient management. Three SSNM treatments based on NE based recommendation were (1) ‘NE80:20’ with 80% N applied at planting and 20% at second irrigation (2) ‘NE33:33:33’ with N split as 33% basal, 33% at Crown Root Initiation (CRI) and 33% at second irrigation; and (3) ‘NE80:GS’ with N split as 80% basal and further application of N based on optical sensor (Green Seeker™)-guided recommendations. Yield, nutrient use efficiency and economic profitability were determined following standard agronomic and economic measurements and calculations. Cool Farm Tool (CFT), an empirical model to estimate greenhouse gases (GHGs) from agriculture production, was used to estimate GHG emissions under different treatments.

Wheat grain and biomass yield were higher under NT in 2010–11 but no difference was observed in 2011–12. The three NE-based nutrient management strategies increased yield, nutrient use efficiency as well as net return as compared to state recommendation and farmers’ fertilization practice. Global warming potential (GWP) of wheat production was also lower with NT system as compared to CT system and NE-based nutrient managements as compared to farmers’ fertilization practice. State recommended nutrient management had similar GWP as NE-based nutrient managements except NE80:GS in which GWP was the lowest. Results suggest that no-tillage system along with site-specific approaches for nutrient management can increase yield, nutrient use efficiency and profitability while decreasing GHG from wheat production in NW India.

Integration of conservation agriculture in smallholder farming systems of southern Africa: identification of key entry points

Posted by Carelia Juarez on , in Journal Articles

Published in International Journal of Agricultural Sustainability, 2013

Christian Thierfelder, Talkmore Mombeyarara, Nelson Mango and Leonard Rusinamhodzi

A component-omission experiment based on the principle of conservation agriculture (CA) was established on smallholder farms for three seasons in Murehwa and Hwedza districts, Zimbabwe; Barue district in Mozambique; Balaka district and Chitedze Research Station in Malawi, and Monze district in Zambia to identify strategies for improving crop productivity and livelihoods for smallholder farmers. The objective of the experiment was to evaluate the effect of tillage, residue retention, fertiliser application and weed control on maize yield. In addition, the study analysed possible combinations of these factors that could provide a sustainable entry point for intensification through CA. Results showed that fertilisation had the strongest effect on crop yield in both tillage systems; adequate fertilisation is therefore key to success in CA. Retention of crop harvest residues increased yield in no-tillage systems; no-tillage without residues depressed yield by 50% when compared with yields of conventional tillage. A step-wise integration of CA into the smallholder farming systems is proposed as a possible strategy to avoid new constraints on smallholder farms. If resources are limiting, farmers may apply all principles on small areas to overcome the initial demand in resources (labour, fertiliser and residues), and once productivity is raised, they can expand.

Maize-based conservation agriculture systems in Malawi: Long-term trends in productivity

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 142 : 47-57, 2013

Christian Thierfelder, John L. Chisui, Mphatso Gama, Stephanie Cheesman, Zwide D. Jere, W. Trent Bunderson, Neal S. Eash and Leonard Rusinamhodzi

In Malawi and throughout much of Africa, maize yields have declined over the past several decades due to continuous cultivation, often in monocropping with little or no inputs. As a result, soil degradation has been aggravated by the loss of valuable top soil caused by rainwater runoff due to the absence of effective conservation practices. To combat this trend, Conservation Agriculture (CA) systems were introduced using a pointed stick or hand hoe to plant directly into untilled soil with crop residues as surface mulch. The objective of this study was to compare the effects of different cropping systems (CA and conventional) on soil physical and chemical parameters and long-term maize productivity in target communities of the southern and central regions of Malawi. This study analysed the effects of CA on soil parameters and maize yield over eight cropping seasons. The biophysical variability of the communities was explored through principal component analysis. Results showed that maize yields in CA systems were strongly affected by rainfall infiltration, which was 24–40% greater compared with the conventional ridge and furrow system. In some cases, maize yields in CA plots were double that of conventional tillage plots. The larger water infiltration observed in CA plots relative to conventional tillage indicated that CA systems may increase access to soil water by the crop and offset the negative effects of seasonal dry spells. Yield benefits of CA over conventional tillage systems were greater especially from the 5th season although, in some instances, greater yields on CA were recorded almost immediately. CA can be practiced in diverse environments from sandy to clay soils, nutrient rich to infertile soils and from low to high rainfall areas as long as adequate inputs (fertilizer, herbicides and labour) are available with good extension support to farmers, especially in the initial years.

A comparative analysis of conservation agriculture systems: Benefits and challenges of rotations and intercropping in Zimbabwe

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 137 : 237-250, 2012

Christian Thierfelder,  Stephanie Cheesman and Leonard Rusinamhodzi

Increasing soil degradation in southern Africa and the potentially negative effects of climate change demand “greener” solutions to reverse this trend. Conservation agriculture (CA) has been proposed as one of those solutions and field level data show marked benefits of this new cropping system. Nevertheless, the use of rotations and/or associations in CA systems is challenging at both the farm and community level. Intercropped maize (Zea mays L.) with grain legumes, cowpea and pigeonpea (Cajanus cajan L. (Millsp.)), as well as maize rotated with cowpea (Vigna unguiculata L. (Walp)) and sunnhemp (Crotalaria ochroleuca L.) was studied for up to eight seasons under CA and conventional agriculture in Zimbabwe. The objective of this study, carried out on-farm and on-station, was to highlight the effects of CA systems on some soil quality indicators and crop productivity. Where possible the specific effects of rotation and intercropping was separated and compared with monocropping. The on-station and on-farm results show: an increase of up to 331% in water infiltration, a 31% greater soil carbon in the top 60 cm than on adjacent conventionally ploughed fields, a 6% lower bulk density in the top 10 cm and 32.5–36 t ha−1 less cumulative soil erosion in CA fields after seven cropping seasons compared with the conventional control treatment. The comparative productivity analysis between continuous maize, maize intercropped with cowpea or pigeonpea and maize in rotation with cowpea or sunnhemp, shows marked benefits of rotation especially in CA systems. The benefits of CA especially when rotated with leguminous crops, increase over time, suggesting that there are improvements in soil structure and fertility. However, field level benefits will not increase the overall adoption of rotations and intercropping in CA systems, unless the socio-economic constraints at the farm and community level are addressed.

Conservation agriculture systems for Malawian smallholder farmers: long term effects on crop productivity, profitability and soil quality

Posted by Carelia Juarez on , in Journal Articles

Published in Renewable Agriculture and Food Systems, 2012

Amos Robert Ngwira, Christian Thierfelder and Dayton M. Lambert

Conservation agriculture (CA) systems are based upon minimal soil disturbance; crop residue retention and crop rotation and/or intercrop association are increasingly seen to recycle nutrients, increase yield and reduce production costs. This study examines the effects of CA practices on crop productivity, profitability and soil quality under the conditions encountered by smallholder farmers in two farming communities from 2005 to 2011 in Malawi, as part of the contribution to remedy a lack of supporting agronomic research for these relatively new systems. The drier agroenvironment of Lemu of Bazale Extension Planning Area (EPA) is characterized by sandy clay loam soils and lower rainfall. Here, CA showed positive benefits on maize yield after the first season of experimentation, with highest increases of 2.7 Mg ha−1 and 2.3 Mg ha−1 more yield in CA monocrop maize and CA maize–legume intercrop, respectively, than the conventional tillage in the driest season of 2009/10. In the high rainfall environment of Zidyana EPA (characterized by sandy loam soils), substantial maize yield benefits resulted in the fifth season of experimentation. Farmers spent at most 50 days ha−1 (US$140) producing maize under CA systems compared with 62 days ha−1(US$176) spent under conventional tillage practices. In Lemu, both CA systems resulted in gross margins three times higher than that of the conventional control plot, while in Zidyana, CA monocrop maize and CA maize–legume intercrop resulted in 33 and 23% higher gross margins, respectively, than conventional tillage. In Zidyana, the earthworm population was highest (48 earthworms m−2 in the first 30 cm) in CA monocrop maize, followed by a CA maize–legume intercropping (40 earthworms) and lowest (nine earthworms) in conventionally tilled treatment. In both study locations CA monocrop maize and CA maize–legume intercrop gave higher water infiltration than the conventional treatment. Improvements in crop productivity, overall economic gain and soil quality have made CA an attractive system for farmers in Malawi and other areas with similar conditions. However, for extensive adoption of CA by smallholder farmers, cultural beliefs that crop production is possible without the ubiquitous ridge and furrow system and residue burning for mice hunting have to be overcome.


Earthworm activity and soil structural changes under conservation agriculture in central Mexico

Posted by Carelia Juarez on , in Journal Articles

Published in Soil and Tillage Research 123: 61-70, 2012

A. Castellanos-Navarretea, C. Rodríguez-Aragonés, R.G.M. de Goede, M.J. Kooistra, K.D. Sayre, L. Brussaard, M.M. Pullema

Crop residue mulching combined with zero tillage and crop rotation, known as conservation agriculture (CA), is being promoted as an alternative system to revert soil degradation in maize-based farming in the central highlands of Mexico. The goal of this paper was to determine the effects of CA vs. conventional tillage systems on soil quality, with a special focus on the role of earthworms in affecting the soil structure morphology, and on crop yield. For the conventional tillage system, the effect of crop residue retention (CONV + RES) was also compared to the conventional farmers’ practice (residues removed; CONV). CA resulted in four times higher earthworm abundance when compared to CONV. Residue retention per se (CONV + RES) did not favor earthworm abundance. In all cases the earthworm community was dominated by exotic species. CA increased total N and soil organic C concentrations relative to CONV, but only at 0–5 cm soil depth. Nevertheless, the more pronounced vertical stratification of soil organic carbon content under CA favored soil surface aggregation and aggregate stability as expressed by the aggregate mean weight diameter after dry sieving (MWDds = 2.6 mm for CA and 1.6 mm for CONV) and wet sieving (MWDws = 0.9 mm and 0.6 mm, respectively). Also, CA improved topsoil water stable macroaggregation (WSA = 415 mg g−1) when compared to CONV (251 mg g−1). Residue retention within conventional tillage (CONV + RES) led to small increases in topsoil aggregate stability (i.e. MWDds and WSA). Soil structural improvements were accompanied by a higher direct surface water infiltration. Micromorphological analysis of thin sections indicated a loose and highly biogenic soil microstructure in CA, whereas CONV was characterized by a physicogenic microstructure, despite similar soil bulk densities (SBD). SBD is thus a poor indicator of soil physical quality when comparing different tillage systems. Redundancy analysis illustrated that CA resulted in improvement in most parameters related to soil quality, especially at the soil surface, but significant yield increases were recorded only in 2004. CONV + RES lead to marginal improvements in soil quality with no yield increases.

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

Posted by on , in Journal Articles

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.