Soil erosion and rainfall-induced runoff are well studied although under field conditions remain somewhat enigmatic. This study quantifies the relationship between rain, overland flow (runoff), erosion and size characteristics of the sediment in China’s northern “corn-belt” during the 2016 growing season. The study site was at the Heilongjiang Experimental Farm (47º23′N, 126º51′E), which is located near Guangrong village in China’s core Mollisol region. Two tillage treatments were evaluated: no-till and conventional till. Each treatment was replicated on runoff plots having 5° (9%) and 7° (12%) slopes. The 5° plots were established in 2006. The 7° plots were established in 2009. Plot size is 20 m long and 4.5 m wide. The experimental control plot is bare soil plot on 5° slope. Results are 394.3 mm rain fell during 54 events between May and November 2016. Runoff as overland flow occurred 14 times in the control, accounted for 25.9% of the precipitation and caused 54.5 tons/ha erosion. At the other end of the data, runoff only occurred twice in the 5° no-till plot and caused only 0.2 tons/ha erosion. Detailed analysis of three rain fall events further validated significant differences in runoff and erosion with each treatment as well as significant differences in size distribution of transported soil solids. Soil solid size distribution and amounts were valuable for describing and analyzing runoff and soil loss processes under different treatments.

The evolution of automorphic cultivated soils of the Fayette series (the order of Alfisols)—close analogues of gray forest soils in the European part of Russia—was studied by the method of agrosoil chronosequences in the lower reaches of the Iowa River. It was found that the old-arable soils are characterized by an increase in the thickness of humus horizons and better aggregation; they are subjected to active biogenic turbation by rodents; some alkalization of the soil reaction and an increase in the sum of exchangeable bases also take place. These features are developed against the background of active eluvial-illuvial differentiation and gleyzation of the soil profiles under conditions of a relatively wet climate typical of the ecotone between the zones of prairies and broadleaved forests in the northeast Central Plains of the United States.

Before 2009, the Natural Resources Conservation Service (NRCS) staff noticed plant roots and argillans deep within the B horizon of Gosport polypedons (a fine, illitic, mesic Oxyaquic Dystrudept) while updating Major Land Resource Area (MLRA) 108 (Illinois and Iowa deep loess and drift) and 109 (Iowa and Missouri heavy till plain) in the central United States. In 2009, Gosport soils in MLRAs 108 and 109 were remapped and reclassified. Both map unit transects and the relevé method were used to identify pedons for detailed laboratory analyses. Eight pedons representing Gosport soils were collected from eight counties in southern Iowa, USA (Davis, Jefferson, Keokuk, Lucas, Mahaska, Marion, Monroe, and Van Buren). All of the pedons were described, analyzed, and classified. The results revealed two groups of soils, which are different than that of Gosport: Alfisols, newly named as the Munterville series (fine, mixed, smectitic or kaolinitic, active or superactive, mesic Oxyaquic Hapludalfs), and Ultisols (fine, mixed or kaolinitic, active, mesic Oxyaquic Hapludults) that have not yet been assigned a series name. The aims of this work were to reclassify the Gosport soils and detect the lithologic discontinuities within their sola.

Accurate characterization of soil properties across a field can be difficult, especially when compounded with the diverse landscapes used for pastureland. Indirect methods of data collection have the advantage of being rapid, noninvasive, and dense; they may improve mapping accuracy of selected soil parameters. The objective of this study was to determine if the use of soil electrical conductivity (EC) as a covariate improved mapping accuracy of five soil variables across four sampling schemes and two sampling densities in a central Iowa, USA pasture. In this study, cokriging methods were compared to kriging methods for the measured soil properties of soil pH, available P and K, organic matter and moisture. Maps resulting from cokriging each of the soil variables with soil EC exhibited more local detail than the kriged maps of each soil variable. A small, but inconsistent, improvement occurred in kriging variance and prediction accuracy of non-sampled sites when cokriging was implemented. The improvement was generally greater for soil variables more highly correlated with soil EC. This work indicates that cokriging of EC with less densely and invasively collected soil parameters of P, K, pH, organic matter (OM) and moisture does not consistently and substantially improve the characterization accuracy of pasture soil variability.

Seventy-six pedologists and related professionals registered to learn about--and contribute to-- the topics of soil survey, soil health, and soil dynamic properties at the 2014 North Central Regional Cooperative Soil survey Conference, held June 2nd through 5th on the campus of Iowa State University. Forty-four of the registrants were USDA--NRCS employees (14 from Iowa, 2 from regional and MLRA offices, and 8 from national postings), and 24 were university employees (7 faculty from ISU, 9 faculty from cooperating universities, and 8 graduate students). The remaining eight registrants were with cooperating agencies from Iowa, Minnesota, or the Federal government. The meeting had three core components: research presentations, technical discussions and updates, and a field trip. The field trip illustrated Iowa soils and mapping issues and opportunities.

Soil surveys are generally treated as static documents. Many soil survey users assume that pedon data generated 30 to 50 yr ago still represents today’s soil, as short-term changes in soil properties are perceived to be limited to the soil surface and thus pedologically insignificant. In this study, we re-sampled and re-analyzed 82 pedons with historical descriptions and laboratory data in Iowa, United States, to evaluate changes in soil profile properties and taxonomic classification after approximately 50 yr of agricultural land use. Using historical and current data, we classified sampled pedons using Canadian Soil Taxonomy, US Soil Taxonomy and the Food and Agriculture Association World Reference Base (FAO-WRB). Our results show that soil characteristics have changed significantly enough to change the classification. In each taxonomic system, the classification of 60% or more of the sampled pedons differed from the original. Classification of 15 to 32% of the sampled pedons changed at the Order (or equivalent) level with 11 to 33% of the pedons originally classified as Black soils Mollisols, Chernozems or Phaeozems no longer classified as Black soils. The change in soil classification over such a short-time period challenges the validity and usefulness of treating existing soil maps as static documents as well as traditional soil classification hierarchies.

Switchgrass (Panicum virgatum L.) is a potential biofuel crop in the midwestern United States. The objective of this experiment was to test the effect of nitrogen application on biomass dry matter yield and fiber and mineral concentrations in large field plots in Lucas and Wayne counties in southern Iowa. Two established switchgrass fields with a previous history of limited management were evaluated from 1998 through 2002. Nitrogen was applied in the spring at rates of 0, 56, 112, and 224 kg N ha⁻¹, and a single biomass harvest was made in autumn. Biomass production averaged across locations and N levels increased by 3.6 mg ha⁻¹ between 1998 and 2002 to 6.5 mg ha⁻¹. Nitrogen improved yields, with the response declining as N levels increased. The highest yield throughout the experiment was 8.5 mg ha⁻¹ at the Lucas location in 2002. Changes in fiber and mineral concentrations did not follow any trend over years but were likely due to differences in harvest date among years. Nitrogen fertilization had no meaningful effect on the quality of the biofuel produced. This study clearly shows that nitrogen application and proper agronomic management can substantially increase the yield of established switchgrass fields over time without affecting the quality of the feedstock. As this experiment was conducted in large plots using commercial farm machinery, the results should be broadly applicable to real world situations.

The objective of this project was to use detailed soil profi le descriptions and soil carbon analyses to determine the soil C sequestration potential of tree planting across climatic gradients in the U.S. Great Plains. Tree windbreak age ranged from 19 to 70 years and age of cultivation from 22 to ~110 years. At each site, soil pits were prepared within the tree planting, the adjacent crop fi elds, and nearby undisturbed grassland. Windbreak soils had consistently thicker soil organic carbon (SOC)- enriched A or A+AB horizons when compared to the crop fi elds. The thickness of A or A+AB horizons in the windbreak soils were comparable to the undisturbed grassland soils. A linear relationship was detected between the difference in A+AB thickness of soils beneath windbreaks and undisturbed grasslands and a climate index (hydrothermal coeffi cient, HTC). These results indicate that tree windbreaks with more cool and moist climate conditions are more favorable for SOC accumulation in the surface soil. The relationship between SOC accumulation and climate factors enables the estimation of soil carbon stocks in existing windbreaks and the prediction of potential carbon sequestration of future plantings.

Mollisols a.k.a., Black Soils or Prairie Soils make up about 916 million ha, which is 7% of the world’s ice-free land surface. Their distribution strongly correlates with native prairie ecosystems, but is not limited to them. They are most prevalent in the mid-latitudes of North America, Eurasia, and South America. In North America, they cover 200 million ha of the United States, more than 40 million ha of Canada and 50 million ha of Mexico. Across Eurasia they cover around 450 million ha, extending from the western 148 million ha in southern Russia and 34 million ha in Ukraine to the eastern 35 million ha in northeast China. They are common to South America’s Argentina and Uruguay, covering about 89 million and 13 million ha, respectively. Mollisols are often recognized as inherently productive and fertile soils. They are extensively and intensively farmed, and increasingly dedicated to cereals production, which needs significant inputs of fertilizers and tillage. Mollisols are also important soils in pasture, range and forage systems. Thus, it is not surprising that these soils are prone to soil erosion, dehumification (loss of stable aggregates and organic matter) and are suffering from anthropogenic soil acidity. Therefore, soil scientists from all of the world’s Mollisols regions are concerned about the sustainability of some of current trends in land use and agricultural practices. These same scientists recommend increasing the acreage under minimum or restricted tillage, returning plant residues and adding organic amendments such as animal manure to maintain or increase soil organic matter content, and more systematic use of chemical amendments such as agricultural limestone to replenish soil calcium reserves.

Rural communities of sub-Saharan Africa are under increasing adaptive pressure resulting from decline in the quality of land resources. To increase food, generate income, and safeguard against risks and shocks, families are engaging in multiple livelihood strategies. This study was conducted to: 1) evaluate livelihood strategies; 2) examine the dynamic diversification process in the agrarian and non-agrarian continuum; and 3) investigate how type and availability of assets influences choice of a livelihood strategy. Results from our investigation in western Kenya suggest that as land is subjected to degradation, there is a shift in the type of assets that families can draw upon. Among the Luo, collision between deeply embedded cultural beliefs and access to land, is leading to a shift from farming to non-farming activities. They are heavily reliant on human labor to make a living hence becoming less resilient, and more vulnerable to existing and emerging risks and shocks. The overriding scenario is escalated land degradation, increased poverty levels, and a failed social support system. Asset diversification and intensification processes among the Kipsigis are closely intertwined with rapid social-cultural change and strong bonding and bridging ties. They are involved in an asset-led intensification and diversification strategies. Overall, our findings suggest that the ability to make a meaningful livelihood is dependent not only on the quality and quantity of assets that an individual household possesses, but also having capabilities to use and transform the assets as well.