Mixtures of modern and historical wheat cultivars under organic management in western Canada

Two historic (Red Fife and Marquis) and two modern (5602HR; AC Barrie) wheat (Triticum aestivum) cultivars were assessed to determine if cultivar mixtures provided a benefit to grain yield and disease and weed suppression in Manitoba over 3 site-years. 5602HR was the highest yielding sole cultivar while Marquis and AC Barrie were the lowest yielding sole cultivars. Red Fife yielded similar to 5602HR in several cases. Orthogonal contrasts across all site-years showed that 3 and 4 cultivar mixtures yielded similar (P>0.05) to 5602HR, the highest yielding monocrop

GRAZING GREEN MANURES TO OPTIMIZE NITROGEN SUPPLY ON THE CANADIAN PRAIRIES

Grazing green manures may improve N availability and productivity in integrated crop-livestock systems. We hypothesized that grazing green manures, compared with standard soil incorporation with tillage, would increase autumn soil profile NO3-N concentrations. Experiments were carried out for three years between 2009 and 2011 in Manitoba, Canada. Seven different green manure crops or mixtures were grazed with sheep or left ungrazed. Hairy vetch, pea/oat mix and oats produced the greatest forage biomass in two out of three years. In 2010, sweet clover produced a similar amount (5813 kg ha-1). Soybean and lentil failed to compete with weeds; containing 30 to 73% weed biomass in all years. Utilization by sheep for all crops ranged from 28% to 86% but the most common range was between 60% and 80%. Soil NO3-N to 120 cm was significantly greater in grazed than in ungrazed plots. Greatest soil NO3-N content (226 kg ha-1) was observed in grazed pea/oat plots in experiment 1 and lowest (44 kg ha-1) was in ungrazed mixture plots in experiment 3. In experiment 1, total profile soil NO3-N level in pea/oat plots was greater than in oat plots. In experiment 2, oat plots contained less NO3-N than pea/oat and mixture plots. In experiment 3, there was significant species and management effect where soil in grazed hairy vetch plots contained the greatest amount of NO3-N. This interaction indicated that increase in soil NO3-N availability is greater when hairy vetch is grazed than grazing of other crops. In situations with low legume biomass productivity, grazing may be used to increase the N benefit from legume green manures to the following crops. Therefore, in addition to single benefit of soil fertility, two benefits were reaped from green manures; potential livestock live weight gain and soil fertility

Potential of Forages in Crop Diversification and Crop Rotation

Redesign of agricultural systems according to ecological principles has been proposed for the development of sustainable systems. We review a wide variety of ecologically-based crop production practices that focus on forage crops in farming systems and discuss their potential role in enhancing the profitability, environmental sustainability and resilience. Crop-livestock systems that most closely mimic natural systems through appropriate integration of diverse components appear to offer the greatest potential benefits. These systems are more energy efficient and combine high productivity with low ecological footprint. Greater understanding of ecological relationships within crop-livestock systems are required to purposefully and proactively redesign agricultural systems for profitability, sustainability and resilience

Assessment of selected soil parameters in a long-term Western Canadian organic field experiment

A long-term field study was used to compare soil nitrogen and phosphorous status, and soil aggregate stability in organic and conventional cropping systems. Two rotations were tested: a grain only and a grain-alfalfa hay rotation. The organic systems had a lower nitrate leaching potential than the same rotations under conventional management. After 13 years, one organic system (the grain-alfalfa; no manure return) is suffering serious soil P depletion. However, the grain only and the grain-alfalfa with manure return to land systems had soil P levels similar to the prairie grass control treatment and showed no signs of P deficiency. Despite having lower levels of organic carbon, the organic soils had higher levels of wet aggregate stability than conventionally managed soils

Ecological approaches to ensuring food security : a learning platform for understanding and advancing conservation agriculture in Africa and Asia; final report

The aim is to embrace and promote agroecological systems in smallholder agricultural production with conservation agriculture (CA) as a starting point, and to better understand limitations for scaling up CA among small-holder farmers. In this detailed report the problem of mulch limitation was identified. A larger survey showed that when farmers expand their CA fields to include larger portions of their farms, the level of herbicide and fertilizer inputs increases. The agroecological platform to this research, in collaboration with farmers, shows that adding legumes to the CA systems increased total food production without reducing maize yield

Ideotype breeding for crop adaptation to low phosphorus availability on extensive organic farms

Organic farming in extensive production regions, such as the Canadian prairies have a particularly difficult challenge of replenishing soil reserves of phosphorus (P). Organic grains are exported off the farm while resupply of lost P is difficult due to limited availability of animal manures and low solubility of rock organic fertilizers. As a result, many organic farms on the prairies are deficient in plant-available P, leading to productivity breakdown. A portion of the solution may involve crop genetic improvement. A hypothetical ‘catch and release’ wheat ideotype for organic production systems is proposed to (i) enhance P uptake and use efficiency but (ii) translocate less P from the vegetative biomass into the grain. Root traits that would improve P uptake efficiency from less-available P pools under organic production are explored. The need to understand and classify ‘phosphorus use efficiency’ using appropriate indices for organic production is considered, as well as the appropriate efficiency indices for use if genetically selecting for the proposed ideotype. The implications for low seed P and high vegetative P are considered from a crop physiology, environmental, and human nutrition standpoint; considerations that are imperative for future feasibility of the ideotype

Evolution of Integrated Crop-Livestock Production Systems

Key points 1. Many factors contribute to changes in the crop-livestock systems, but no logical end-point in the evolution process exists. 2. While benefits of integrated crop-livestock systems over specialised crop and livestock systems are well documented, there has been a move to specialised crop and livestock production. 3. Sustainability issues (manure nutrient concentration, soil quality maintenance, salinity, herbicide resistance, economic instability) have created a renewed interest in integrated crop-livestock systems. 4. Farmer adaptability is as an important link in the evolution between ‘states of integration’

Evolution of Integrated Crop-Livestock Production Systems

Many factors contribute to changes in the crop-livestock systems, but no logical end-point in the evolution process exists. While benefits of integrated crop-livestock systems over specialised crop and livestock systems are well documented, there has been a move to specialised crop and livestock production. Sustainability issues (manure nutrient concentration, soil quality maintenance, salinity, herbicide resistance, economic instability) have created a renewed interest in integrated crop-livestock systems. Farmer adaptability is as an important link in the evolution between ‘states of integration’

Shallow non-inversion tillage in organic farming maintains crop yields and increases soil C stocks: a meta-analysis

Reduced tillage is increasingly promoted to improve sustainability and productivity of agricultural systems. Nonetheless, adoption of reduced tillage by organic farmers has been slow due to concerns about nutrient supply, soil structure, and weeds that may limit yields. Here, we compiled the results from both published and unpublished research comparing deep or shallow inversion tillage, with various categories of reduced tillage under organic management. Shallow refers to less than 25 cm. We found that (1) division of reduced tillage practices into different classes with varying degrees of intensity allowed us to assess the trade-offs between reductions in tillage intensity, crop yields, weed incidence, and soil C stocks. (2) Reducing tillage intensity in organic systems reduced crop yields by an average of 7.6 % relative to deep inversion tillage with no significant reduction in yield relative to shallow inversion tillage. (3) Among the different classes of reduced tillage practice, shallow non-inversion tillage resulted in non-significant reductions in yield relative to deep inversion; whereas deep non-inversion tillage resulted in the largest yield reduction, of 11.6 %. (4) Using inversion tillage to only a shallow depth resulted in minimal reductions in yield, of 5.5 %, but significantly higher soil C stocks and better weed control. This finding suggests that this is a good option for organic farmers wanting to improve soil quality while minimizing impacts on yields. (5) Weeds were consistently higher, by about 50 %, when tillage intensity was reduced, although this did not always result in reduced yields

Carbon-sensitive pedotransfer functions for plant available water

Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience