of land-related characteristics of a region and are fundamentally carried out to facilitate the extrapolation of The northern Great Plains have long been dominated by conveninformation from the research site to like conditions tional tillage systems and cereal-based rotations including summer fallow. Over the last decade, however, the use of conservation tillage elsewhere. Conceptually, the research procedure is gensystems has markedly increased and, through improved moisture stor-erally as follows: Agronomic research is first carried age, has provided an opportunity for more diversified extended rotaout under controlled conditions resulting in a particular tions including oilseed, pulse, and forage crops throughout the region. finding or findings. Based on the finding(s), a model is Considerable research is being carried out to assess the adaptability developed to predict what comparable finding(s) would of these new crops and to develop appropriate management strategies. be under the breadth of conditions (soil, climate, and Typically, this type of agronomic research is carried out at plot-sized management) found in the region. Finally, the land reresearch sites, with the findings then being extrapolated to surrounding source inventory documents where specific conditions regions where growing conditions are thought to be reasonably similar.occur or in other words, provides spatial information to Because the environment itself largely dictates the success of a particuapply the model and effect the extrapolation. lar cropping system, extrapolation requires knowledge of the environmental conditions of the region and, in particular, the interaction of This paper documents the distribution of the major environmental components of soil and climate in relation to specific land resource areas, or agroecoregions, of the northern crop requirements. This paper describes 14 agroecoregions in theGreat Plains and provides an initial framework for the northern Great Plains and provides an initial framework for extrapoextrapolation of pertinent agronomic information from lating agronomic information at broad regional scales. Because climate the research site to areas of similar environmental condiis the dominant crop production factor in the region, most of the tions. Each agroecoregion is described in terms of its agroecosystems represent broad climatic zones. Each agroecoregion soil and landscape characteristics, with a particular focus is described in terms of its soil and landscape characteristics, with a being given to likely key environmental parameters reparticular focus being given to likely key environmental parameters lated to the production of oilseed, pulse, and forage related to the production of the new oilseed, pulse, and forage crops crops being introduced in the region. Climate data are being introduced in the region.

The impact of soil degradation on human welfare and the global environment presents a major challenge. A significant decline in soil quality has occurred worldwide through adverse changes in its physical, chemical and biological attributes and contamination by inorganic and organic chemicals. There is a need to develop criteria to evaluate soil quality so that the progress of any corrective action required by the international community can be monitored.There currently are no generally accepted criteria to evaluate changes in soil quality. This lack impedes the design and evaluation of meaningful soil management programs. This paper examines the principal physical and chemical attributes that can serve as indicators of a change in soil quality under particular agroclimatic conditions. Proposed indicators include soil depth to a root restricting layer, available water-holding capacity, bulk density/penetration resistance, hydraulic conductivity, aggregate stability, organic matter, nutrient availability/retention capacity, pH, and where appropriate, electrical conductivity and exchangeable sodium. We also discuss the justification for selecting these key attributes, their measurement, critical limits for monitoring changes in soil productivity, and future research needs in soil quality.

The northern Great Plains have long been dominated by conventional tillage systems and cereal‐based rotations including summer fallow. Over the last decade, however, the use of conservation tillage systems has markedly increased and, through improved moisture storage, has provided an opportunity for more diversified extended rotations including oilseed, pulse, and forage crops throughout the region. Considerable research is being carried out to assess the adaptability of these new crops and to develop appropriate management strategies. Typically, this type of agronomic research is carried out at plot‐sized research sites, with the findings then being extrapolated to surrounding regions where growing conditions are thought to be reasonably similar. Because the environment itself largely dictates the success of a particular cropping system, extrapolation requires knowledge of the environmental conditions of the region and, in particular, the interaction of environmental components of soil and climate in relation to specific crop requirements. This paper describes 14 agroecoregions in the northern Great Plains and provides an initial framework for extrapolating agronomic information at broad regional scales. Because climate is the dominant crop production factor in the region, most of the agroecosystems represent broad climatic zones. Each agroecoregion is described in terms of its soil and landscape characteristics, with a particular focus being given to likely key environmental parameters related to the production of the new oilseed, pulse, and forage crops being introduced in the region.

No abstract

The effect of soil properties and weather on herbicide persistence and injury to following crops were studied at a site near Lethbridge, Alberta, Canada, with undulating topography that included no-tillage and conventional tillage systems on adjacent fields. Soil pH ranged from 5.2 (lower slope no-tillage) to 7.8 (upper slope conventional tillage) and soil organic matter content ranged from 2.3% (upper slope conventional tillage) to 4.4% (lower slope no-tillage). During the years when the experiments were conducted rainfall ranged from < 50% of normal to > 150% of normal. During dry years atrazine and metsulfuron severely injured wheat and lentil crops, seeded 1 yr after herbicide application, on upper slope locations. The most severe injury occurred on the upper slope conventional tillage location. In years with high rainfall, no crop injury occurred 1 yr after atrazine and metsulfuron application on either upper or lower slope locations in both tillage systems. Imazamox plus imazethapyr caused almost 100% injury in the lower slope position in the no-tillage system (pH 5.2) in the driest year. Following-crop injury due to the imidazolinone herbicides decreased with increasing rainfall and increasing soil pH. The most severe injury to following crops seemed to occur when herbicide dissipation was dependent on microbial activity and rainfall was below normal.