Crop sequence complexity of the major land resource areas (MLRA) in the contiguous United States (CONUS)

Reference site selection based on state-and-transition models for soil health gap evaluation within cropland reference ecological units

Riparian buffers can improve water quality, but watershed‐scale evaluations of riparian buffering opportunities are rare. A landscape discretization tool called riparian catchments, part of the Agricultural Conservation Planning Framework (ACPF) version 3, was applied to evaluate functional riparian settings for 32 headwater watersheds representing three major land resource areas (MLRAs) in Iowa. Riparian settings of 250‐m length were classified based on height above channel and upslope contributing area to show where to place buffers primarily designed to intercept runoff, treat nitrate in shallow groundwater, and/or protect streambanks. Riparian zones found below small riparian catchments were common, typically occupying >50% of streambank lengths in MLRA 103 (northern Iowa) and MLRA 108 (southeast Iowa). In these settings, narrow (6–10 m wide) buffers provide a buffer/contributing area ratio of >0.02 to filter surface runoff, while providing streambank protection. This similarity occurred despite these two MLRAs having contrasting landscapes. Whereas the narrow buffers suggested are associated with ditches and flat terrain in MLRA 103, they occur below short slopes along streams that have well dissected the watersheds in MLRA 108. In MLRA 104 of east‐central Iowa, headwater alluvial streams often had broad low‐lying riparian zones, where wide buffers (>25 m) may be placed to help mitigate nitrate transport in shallow groundwater. The ACPF riparian catchments approach enabled cross‐watershed analyses of riparian settings, while providing spatial data to inform watershed‐scale riparian planning efforts.

A national effort is underway to update Major Land Resource Areas (MLRAs) by 2002. The criteria for delineating MLRAs have been revised to define them based on soils, soil moisture and temperature regimes, native vegetation, and landforms. Less emphasis is being placed on land use at this level, but land use will be a consideration in subdivisions of MLRAs referred to as Common Resource Areas . In Wisconsin, the National Hierarchical Framework of Ecological Units (NHFEU), at the Landtype Association (LTA) level, was used as a significant source of information for this update. Landtype Associations are delineated at a larger scale using the same basic criteria as MLRAs, but with a few additional elements, such as disturbance regimes. MLRAs in Wisconsin are now meshed with NHFEU, with LTAs serving as the common link. This is significant because not only do the two land classification systems mesh in Wisconsin, which partially satisfies a related national goal, but also, important soil data will be readily accessible to use with the NHFEU. With MLRAs, CRAs, STATSGO, and soil survey map units meshed with the NHFEU in Wisconsin, each NHFEU strata could be linked to the same national soil survey database. Equally important, MLRAs will have access to NHFEU ecological data. This will benefit all users of these two land classification systems.

Spatial patterns and total amounts of soil organic C (SOC) are important data for studies of soil productivity, soil hydraulic properties, and the cycling of C‐based greenhouse gases. This study evaluated several approaches for characterizing SOC to determine their relative merits. The first approach entailed grouping data from a global pedon SOC database by type of ecosystem, resulting in a total of 78.0 Pg of C (Pg = 10 15 g) to 1‐m depth for the contiguous USA. In a second approach, a pedon database was aggregated using soil taxonomy, resulting in a total for the contiguous USA of 80.7 ± 18.6 Pg of C when the great group SOC was spatially distributed with Major Land Resource Areas (MLRAs) using the 1982 National Resource Inventory (NRI) and the Soil Interpretation Record databases. The third approach used pedon and spatial data from a global soil map grouped by soil unit that resulted in 84.5 Pg of C for the contiguous USA. Although the ecosystem and soil taxonomic approaches resulted in similar totals, the taxonomic approaches are recommended because they gave more realistic results in areas of Histosols, shallow soils, and soils with high rock fragment content. The ecosystem approach did not give reliable spatial patterns and is only useful for very broad‐scale work where precisely georeferenced data are not needed. Grouping data by great group provided more information than grouping by order or suborder. The approach based on soil taxonomy is very useful because it is based on the NRI statistical framework and it allows stratification by other NRI items, such as land use and vegetation.

Abstract. When Albania emerged from its seclusion in 1991, the scientific community had its first opportunity to interact with its international counterparts. Soil resource assessment was made with systems developed in the early 1950s, laboratory facilities to provide supporting data were poor, and it was recognized that a new assessment was urgently needed. The country faces a major challenge in reforestation and soil conservation against a background of overgrazing by sheep and goats and clearing of trees and scrubs for fuelwood. Even orchard and olive trees were used as fuelwood during the winters of 1990 and 1991. Since then, gully and rill erosion has accelerated on many of the sloping lands. In addition to reforestation and conservation measures to reduce the pressures on the sloping land, it is necessary to enhance productivity on the fertile valley bottom soils where most of the agriculture is confined. In the recent past, grain yields have declined due to reduced fertilizer use (low purchasing capacity), and poor management practices. More recently productivity has slowly improved, but land degradation, particularly erosion, has visibly increased. USDA Natural Resources Conservation Service in collaboration with the Land Resources Institute of Albania, initiated work on a new national soil map through collation of existing information and field studies. The land unit for land use planning, evaluation, and general management decisions, is the Major Land Resource Area (MLRA). Each MLRA encompasses geographically associated soils, the majority of which have broadly similar patterns ofclimate, water resources, and land uses. The MLRAs presented here are based on the soil map of Albania at 1 : 200 000 scale. The MLRA information provides an overview of the landscape and natural resources. It can be used to assess land suitability for various crops, opportunities to achieve self sufficiency in food production, selection of areas for both field crops and highvalue crops for export, and identification of appropriate farming system technologies. Each MLRA will have a set of degradation processes which can be flagged, therefore each of them becomes a unit for decision making with respect to investments in research and mitigating technologies. The task is far from complete. Appropriate databases are needed to support the decisions that are being made at national level. To complement the MLRA and related database, decision support systems are needed for the important task of developing policy options.

Spatial distribution information about soil organic C (SOC) pools at a proper scale is critical for developing feasible C sequestration programs. This study characterizes the spatial variation in SOC pools related to soil taxon, Major Land Resource Area (MLRA), and land use. Grouping data by the land uses associated with soil orders within each MLRA leads to a statewide average SOC pool of 10.2 ± 2.8 kg m −2 in the upper 1‐m depth, ranging from 7.1 kg m −2 in Ultisols to 117 in Histosols (8.8, 11.3, 12.7, and 16.9 kg m −2 in Alfisols, Inceptisols, Entisols, and Mollisols, respectively), and geographically varying from 7.7 kg m −2 in MLRA 124 to 12.0 in both MLRA 99 and 111. These variations can be also partially attributed to the properties for suborder differentiation. Moreover, land use effects are confounded by preferential selection of land for cropland use and site topographic features, resulting in a higher SOC pool in cropland (10.9 kg m −2 ) than in both forestland (9.5 kg m −2 ) and pastureland (8.4 kg m −2 ). The grand total SOC storage in Ohio ranges from 853 to 881 Tg (1 Tg = 10 12 g). The SOC pool is primarily related to landscape slope and soil drainage, and must be considered in interpretations for C sequestration potential among land uses for each soil taxon at the MLRA scale.

A Soil and land Use Map of Pohru catchment was prepared through the adoption of a systematic Air Photo-interpretation procedure including selective field studies in such a manner that the ten delineated mapping units were co-extensive with major Land Resource Areas. Defined in terms of physiography, soil profile, soil erosion and present land use each of the ten units has unique characteristics requiring differential management, which was arrived at through joint field studies by Pedologists who prepared the Map, Foresters, Soil Conservationists, Agronomists. a Horticulturist and an Agricultural Chemist. Stemming from this integrated effort a Land Use Plan for the catchment was drawn up with its major objective as the conservation of Land and Soil Resources leading to a reduction in sediment yields that are now so high as to clog the Jhelum river at the polnt where Pohru river joins it. In respect of four Land Resource areas, the plan prescribes radical readjustments of Land Use such as conversion of Forest Department owned Himalayan Southern slopes to grass lands, change of cropping pattern in Karewa side slopes and conversion of the northern and southern Himalayan footslopes now under cultivation into orchards. The areal extents of the different Land Resource Areas as also the cost of implementing the conservation recommendations have been furnished for every one of the twentyeight watersheds falling under the eight subcatchments of the Pohru catchment. The total cost of implementing the conservation recommendations approximates to about fifty five million rupees.

Identification of Köppen climate classification and major land resource area in the United States using a smartphone application

Diversity of diagnostic horizons in soils of the contiguous USA: A case study

Slope failure probabilistic models generated using random forest (RF) machine learning (ML), manually interpreted incident points, and light detection and ranging (LiDAR) digital terrain variables are assessed for predicting and generalizing to new geographic extents. Specifically, models for four Major Land Resource Areas (MLRAs) in the state of West Virginia in the United States (US) were created. All region-specific models were then used to predict withheld validation data within all four MLRAs. For all validation datasets, the model trained using data from the same MLRA provided the highest reported overall accuracy (OA), Kappa statistic, F1 Score, area under the receiver operating characteristic curve (AUC ROC), and area under the precision-recall curve (AUC PR). However, the model from the same MLRA as the validation dataset did not always provide the highest precision, recall, and/or specificity, suggesting that models extrapolated to new geographic extents tend to either overpredict or underpredict the land area of slope failure occurrence whereas they offer a better balance between omission and commission error within the region in which they were trained. This study highlights the value of developing region-specific inventories, models, and high resolution and detailed digital elevation data, since models may not generalize well to new geographic extents, potentially resulting from spatial heterogeneity in landscape and/or slope failure characteristics.

Fragipan horizon identification is based on seven field clues, none of which are quantitative in nature. The ability of uncemented horizons (including fragipans) to slake or fracture when immersed in water is the basis for the last of these clues. The objectives of this study are to determine if slaking is unique to fragipan horizons and to quantify slaking in selected horizons from soil of the southern Mississippi Valley Silty Uplands, designated as Major Land Resource Area (MLRA) 134. Clods from Btxl horizons of Loring and Grenada soils (fine‐silty, mixed, thermic Typic Fragiudalfs and fine‐silty, mixed, thermic Glossic Fragiudalfs, respectively) and Bt horizons of Memphis soils (fine‐silty, mixed, thermic Typic Hapludalfs) were used for comparisons. Slaking was quantified by weighing the air‐dried clods and measuring the length of time required for the clod to completely slake after being immersed in water. All of the horizons investigated slaked in water. Although slaking rates varied from site to site, samples from the Btxl horizon of the Loring and Grenada pedons (2.3 and 1.7 g min ‐1 , respectively) were significantly lower (slower) than those from the Bt horizon of the Memphis pedons (4.6 g min ‐1 ). Regression analysis suggests a weak to no relationship of slaking rates to sand content ( r 2 = 0.24) and no relationship of slaking rates to silt or clay content, or to extractable Fe or Si. The data presented suggest that quantified slaking rates may be useful in differentiating fragipans, but the data set needs to be expanded to include other parent materials and soils from other MLRAs.

Samples of 255 noncalcareous A, Ap, and AB horizons from selected major land resource areas (MLRA) in the north central USA were used to develop equations for predicting organic C content, as determined with a Leco C analyzer, from weight loss‐on‐ignition (LOI). Organic C concentrations of the samples ranged from 1.09 to 114.6 g kg −1 Within each MLRA, strong linear relationships were observed between LOI and organic C measured by the Leco instrument, with r 2 ranging from 0.94 to 0.98. Predictive equations developed by least‐squares regression were significantly different for individual MLRA's. Loss‐on‐ignition is a rapid, inexpensive, and accurate method for estimating organic C concentration in soils of the north central USA. We recommend that unique predictive equations be developed for individual soil‐geographic regions.

The data set contains stream water concentrations of herbicides and nutrients for 153 sites in the northern Missouri/southern Iowa region from 1994 to 1995 and additional data from 1996 to 1999 for 21 sites. The data are available in Microsoft Excel 2010 format. Sheet 1 (Metadata) of the file contains supporting information regarding the length of record, site locations, parameters measured, concentrations units, method detection limits, describes the meaning of zero and blank cells, defines the major land resource areas (MLRAs) of the region, and provides a link to the U. S. Geological Survey discharge data. Sheet 2 (Site names and locations) has a list of the site names by MLRA, river system, and site name. It also contains site locations, provided as Universal Transverse Mercator coordinates, drainage areas, and indicates which sites were co-located at U. S. Geological Survey gauge sites. Sheet 3 (Concentration Data) contains data for 15 herbicide and nutrient analytes along with the corresponding site name, river system, and MLRA.

Biomass crop production on representative Southeastern US farms: Farm profitability, erosion control and the 1985 food security act

Carbon sequestration potential estimates with changes in land use and tillage practice in Ohio, USA