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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.

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Minesoils from 1 to 50 years old in southeastern Montana were compared to adjacent natural soils. Due to their maninfluenced origin, minesoils had several unique morphological properties which made them difficult to classify. Weakly consolidated rock fragments, common in minesoils, acted in part like soil in supplying water and in part like rock in preventing root penetration. Low chroma mottles were common in minesoils without the influence of a high water table. Organic C content from 0–10 cm soil depth reached levels found in natural soils within 30 years, but will not reach equilibrium at 20–50 cm for 400 years or more. Litter accumulation was common under pioneer vegetation on minesoils resulting in wide C/N ratios; reduction in available N; successional stagnation; and reduced plant community production. Soluble salts were leached downward in minesoils in tens of years, but thousands of years will probably be required for carbonate removal to occur in the upper 50 cm. Soil structure developed more quickly near the soil surface (10–50 years) than below 10 cm (50–200 years), and was attained sooner in clayey than in sandy minesoils. Many characteristics of minesoils are expected to always be different from natural soils. Well‐designed minesoils can be highly productive, however, in a few cases perhaps exceeding the potential of natural soils.

Farm fields are traditionally fertilized as one homogeneous soil unit. Most fields, however, contain two or more soils with different crop yield potentials. This study was conducted to (i) measure crop yield differences between contrasting soils within fields, and (ii) compare the economics of “farming soils, not fields,” where contrasting soils in a field receive different vs. uniform rates and formulations of fertilizer. Crop yield variability studies were conducted along 1600 ft transects across several soil units in each of four fields during 1987. Grain yield, test weight, and returns over variable costs varied greatly among soil units in each field (P < 0.05). Soil fertility studies also revealed differences in grain yield, test weight, and returns among soil units in five fields during 1987 and 1988. Fertility studies indicated yields were similar for small grains when recommended fertilizer treatments were applied as soil unit treatments rather than as a field treatment. Returns were $2.06 to $5.14 greater per acre for the soil treatment than for the field treatment in three of five fields, but overall, the returns were not significantly different. A recommended fertilizer treatment was not always the optimum treatment, however. In two fields, additional returns of $21.68 to $23.51 /acre resulted when optimum soil treatments were applied rather than the field treatment. The data reveal the importance of appropriate crop yield goals, accurate soil tests, and reliable fertilizer recommendations when developing a strategy for generating greater returns by farming soil, not fields. Given these caveats, our work suggests that farming soils, not fields will increase fertilizer profitability.

Data describing 130 A horizons were extracted from the Montana Soil Pedon Database to determine whether there is a relationship between soil clay content and organic C. All sites sampled had either frigid or cryic temperature regimes. The pedons were grouped according to land use, soil classification, temperature regime, and horizon position. Correlations between organic C and clay content were not significant for any group. Apparently clay content has much less influence on organic C accumulation in cool soils of Montana than it does in warmer soils of the southern Great Plains. In Montana, organic C content is better predicted by elevation and mean annual precipitation. The r value for a multilinear regression equation using these variables was 0.88.

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