Guy R. Mehuys

Farm-Scale Agronomic and Economic Conversion from Conventional to Sustainable Agriculture

Publisher Summary Conversion process has three components—including increased efficiency, substitution, and redesign. This chapter focuses on research that addresses conversion to the early stages of redesign, emphasizing methods that are relatively easy to implement, and that minimize financial risk. Many farmers experience a major shift in their values, and place even greater emphasis on their role as guardians of human health, through the provision of essential nutrients to consumers, and of the health of the rural community and environment. Another common change is that farmers become more aware of the “organismal” nature of the farm, which functions well when all its components are present and essential biological processes are supported through the careful management of events in time and space. The conversion process usually takes from three to six years. Because of the uniqueness of each situation and the changing nature of environments, there can be no reliable formulas for successful transition. The chapter discusses the research results concerning some critical aspects of any conversion plan.

Agricultural Science and Sustainable Agriculture: a Review of the Existing Scientific Barriers to Sustainable Food Production and Potential Solutions

ABSTRACT Traditional approaches to agricultural science present a number of barriers to increasing our understanding of sustainable agriculture. Logical positivist and reductionist methods limit the information that can be obtained from complex biological systems, and institutional forces help to prevent scientists from exploring comprehensive and new directions that do not fit the predominant paradigms. A diverse range of political and institutional strategies for supporting research in sustainable agriculture is proposed.

Decomposition of grain-corn residues (Zea mays L.): A litterbag study under three tillage systems

This study was undertaken to obtain litterbag decomposition data for grain-corn residues in eastern Canadian conditions, to determine tillage and/or depth effects on residue mass loss, and to compare decomposition patterns for the different plant parts that constitute the residue (cobs, stems, leaves, husks). Mesh bags containing residues were buried or left on the soil surface in grain-corn plots under no-till, reduced tillage, and conventional tillage, and retrieved over a 2-yr period. Data were obtained separately for each plant part, then used to calculate pooled totals for all residues combined, for all residues except cobs, or for stems and leaves only, to facilitate comparison with studies based on different residue mixes. Buried residues lost mass faster than surface residues. Despite low overwinter temperatures, residue mass decreased substantially between placement in November and first sampling in mid- May. Surface litterbag residues lost 20% of initial mass during this period, residues buried ...

Effects of Green Manuring in Rotation with Corn on the Physical Properties of Two Quebec Soils

ABSTRACT The purpose of this study was to determine whether green manure used either in rotation or intercropped with corn could increase soil organic-matter levels and improve soil physical conditions. Eight treatments were applied for a 3-year period to a Bearbrook clay and a Franklin gravelly loamy sand in a rotation experiment. Aggregate-size distribution, bulk density, moisture retention, and water flow were measured for each soil. Green manures tended to increase organic-matter levels on the Bearbrook site over the three years of the experiment, although the increase was not statistically significant. On the Franklin site, no increase in organic-matter levels due to treatment was noted. Incorporating red clover into the Bearbrook soil improved dry-aggregate distribution and reduced bulk density but did not increase the stability of aggregates in water. Infiltration did not improve in response to green manuring. Incorporating common vetch or buckwheat into the Franklin soil did not affect any physica...

An artificial neural network to estimate soil temperature

This study was undertaken to develop an artificial neural network (ANN) model for transient simulation of soil temperature at different depths in the profile. The capability of ANN models to simulate the variation of temperature in soils was investigated by considering readily available meteorologic parameters. The ANN model was constructed by using five years of meteorologic data, measured at a weather station at the Central Experimental Farm in Ottawa, Ontario, Canada. The model inputs consisted of daily rainfall, potential evapotranspiration, and the day of the year. The model outputs were daily soil temperatures at the depths of 100, 500 and 1500 mm. The estimated values were found to be close to the measured values, as shown by a root-mean-square error ranging from 0.59 to 1.82 °C, a standard deviation of errors from 0.61 to 1.81 °C, and a coefficient of determination from 0.937 to 0.987. Therefore, it is concluded that ANN models can be used to estimate soil temperature by considering routinely meas...

Long-term effects of a single incidence of high axle load compaction on a clay soil in Quebec

Abstract The long-term effects of a single incidence of compactive loads of 12 and 20 Mg per axle on a clay soil are evaluated. Changes in soil bulk density and crop performance under monocultural row production were monitored over the 7 year period following loading. Soil bulk densities were significantly increased by the initial high axle load compaction. Bulk densities in both compacted and uncompacted plots continued to increase in a monocultural corn production system. The effect of residual compaction on total plant dry matter yields lasted for 4 years. Grain yield reductions persisted for up to 6 years after compaction. In both cases, however, yields showed an improving trend throughout the study period.

Effect of tillage reduction and fertilizer type on soil properties during corn (Zea mays L.) production.

Continuous corn production (Zea mays L.) and intensive tillage have been linked to increased soil erosion and compaction in eastern Canada. Combining reduced-tillage practices with the use of manure as a fertilizer might help to avert such problems. Direct drilling, chisel, and moldboard plowing were compared on a clay and a sandy loam. At the same time, nitrogen was supplied either by an inorganic fertilizer or by fresh dairy manure. Replacing moldboard plowing by zero-till increased soil density and soil water content. The effects of chisel plowing were intermediate between those of direct drilling and those of moldboard plowing. Manure application decreased soil density and increased water content. Phosphorus and potassium tended to accumulate in the surface layer of the zero-till treatment but it was not a problem for plant growth. Soil inorganic nitrogen levels were considerably lower when manure was used instead of an inorganic fertilizer, resulting in lower plant uptake.

Response of grain corn to subsoiling and chemical wetting of a compacted clay subsoil

Abstract The effect of annual compactive loads of 10 and 18 Mg per axle on soil structure and crop yields were compared with effects of loads limited to 5 Mg per axle. Chemical conditioning and subsoiling were also applied to determine their alleviating effects. Significant topsoil and subsoil compaction resulted from both loading levels. Maximum dry bulk densities of up to 1.79 Mg per m−3 were observed in the subsoil at depths between 0.2 and 0.3 m. Compactive loading significantly reduced subsoil pore sizes greater than 30 μm. Crop yield reductions ranged from 18 to 27% under optimal weather conditions and were as high as 55–86% under adverse weather conditions. Chemical conditioning had no significant effect on soil bulk densities but was associated with improved crop yield in a year with above normal precipitation. Changes observed in water retention were attributable to the effects of the conditioner on water desorption characteristics. Inter-row subsoiling with narrow-tined and winged subsoilers was effective in loosening the compacted profiles, but improvements in crop response varied according to rainfall regime.

Agronomic and economic feasibility of growing corn (Zea mays L.) with different levels of tillage and dairy manure in Quebec

Abstract In order to assess the agronomic and economic feasibility of growing corn under reduced tillage using manure as a source of fertilizer, a study of silage and grain corn ( Zea mays L.) production using three levels of tillage (conventional, reduced and zero till) and two types of fertilizer (inorganic fertilizer and dairy manure) was initiated on a clay soil and a sandy loam soil in 1981 at Macdonald College. Results obtained between 1983 and 1986 showed that good yields could be obtained with zero and reduced tillage in combination with inorganic fertilizers. The use of dairy manure in combination with conventional and reduced tillage resulted in good plant yields at the sandy loam site but decreased plant yield at the clay site. The practice of zero till in combination with manure resulted in difficulties with weed control, poor seed emergence and a greater risk of frost damage in the spring. The costs of production were lowest when zero till was used in association with inorganic fertilizers.

The Canon of Potato Science: 30. Tillage Erosion within Potato Production – Soil Tillage, Earthing Up and Planting

Tillage erosion is the redistribution of soil that occurs within a landscape as a direct result of tillage operations. Tillage is an integral part of potato production, and in all tillage operations, displacement, sorting and mixing of soil occur. The displacement and resulting transport of soil across the landscape are referred to as tillage translocation. Tillage erosion occurs whenever the quantity of soil translocated out of an area of the field is different from that translocated into that area. Within the field, tillage erosion is typically observed as: