Abstract The percentage of soil pore space filled with water (percent water‐filled pores, % WFP), as determined by content and total porosity, appears to be closely related microbial activity under different tillage regimes. Soil incubated in the laboratory at 60% WFP supported maximum aerobic CO 2 production O uptake. In field, surface no‐tillage soils (0–75 mm) four U.S. locations averaged 62% time sampling, whereas that for plowed was 44%. This difference reflected 3.4 9.4 times greater N...

Abstract This essay summarizes deliberation by the Soil Science Society of America (SSSA) Ad Hoc Committee on Quality (S‐581) and was written to spur discussion among SSSA members. Varying perceptions soil quality have emerged since concept suggested in early 1990s, dialogue members is important because, unlike air water quality, legislative standards for not been perhaps should be defined. In simplest terms, “the capacity (of soil) function”. definition, based function, reflects living...

Abstract Tillage intensity affects soil structure and the loss of organic C N. We hypothesized that no‐tillage (NT) conventional tillage (CT) differentially affect three physically defined particulate matter (POM) fractions. A grassland‐derived Haplustoll was separated into aggregates by wet sieving. Free light fraction (LF) intra‐aggregate POM (iPOM) were isolated. Natural abundance 13 measured for whole C, free LF iPOM C. The mean residence time under CT (44 yr) 1.7 times less than in NT...

Biological denitrification is affected by many environmental factors that control the amount of N2 and N2O entering atmosphere. This study was conducted to measure effect water-filled pore space (WFPS), available C, soil NO3 concentration on total (N2 + N2O), using acetylene (C2H2) inhibition, ascertain if could be estimated from measurements in field an average N2/N2O ratio. Repacked cores four benchmark soils were brought 60, 75, 90% WFPS applying treatments glucose-C (0, 180, 360 kg ha−1)...

Abstract Soil physical properties often regulate aeration‐dependent microbial activities important to nutrient cycling, soil fertility and environmental quality. Microbial activity depends on water content is maximum at a where the limiting effects of substrate diffusion O 2 supply are equal. The mechanism whereby this occurs predictions aerobic were objectives study. In particular, study predicted shape vs. function from concepts. processes assumed influence by steady flux required or sites...

Soil textural analysis is a key component of any minimum data set used for assessing soil quality and sustainability agricultural-management practices. However, conventional methods can be costly time-consuming. The objective this study was to develop rapid simple method evaluating particle-size distribution, which could employed as tool initial soil-quality assessment. uses combination sieving sedimentation steps designed in conjunction with particulate organic matter (POM), or stand-alone...

Abstract Nutrient release from legume and cereal crop residue is important to N crycling the success of conservation sustainable farming systems. Residue type, placement, degree incorporation, soil water regimes largely control availability loss were evaluated in laboratory. Four residues, i.e., vetch ( Vicia villosa Roth.), soybean Glycine max [L.] Merr.), corn Zea mays L.), wheat Triticum aestivum L.) having C/N ratios ranging 8 82 applied on surface or incorporated repacked cores a...

Abstract Surface soils from long‐term tillage comparison experiments at six U.S. locations were characterized for aerobic and anaerobic microbial populations denitrification potential using an in situ acetylene blockage technique. Measurements of soil water content, bulk density, relative differences pH, NO ‐ 3 ‐N, water‐soluble C, total C N contents between treatments also determined the time sampling. Numbers microorganisms surface (0–75 mm) no‐till averaged 1.35 to 1.41 1.27 1.31 times...

Abstract The impact of organic production practices on soil quality indicators, for selected farms in Nebraska and North Dakota, were evaluated to better understand their effects sustainability. Conventional the standard which compared. Five conventional farms, matched by type, chosen study. Soil properties recognized as basic indicators measured each farm at depths 0 7.6 30.5 cm. Averaged across locations, there was 22% more C (12 571 kg ha −1 ) 20% total N (970 than surface At four five...

Abstract Evaluation of microbial populations and activities, their relationship to N cycling in soils under organic conventional farm management was conducted eastern Nebraska 1981 1982, on an experiment initiated 1975. The experimental treatments consisted 3 × 4 factorial with three systems (organic, fertilizer only, plus herbicide) for a 4‐yr grain/legume crop rotation one treatment continuous corn ( Zea mays L.) receiving fertilizer, herbicide, insecticide (including subplot without...

Runoff from a cow-calf pasture in eastern Nebraska was monitored for total coliforms (TC), fecal (FC), and streptococci (FS) during 1976, 1977, 1978. Bacteriological counts runoff both grazed ungrazed areas generally exceeded recommended water quality standards. The FC group the best indicator of impact grazing. Rainfall area contained 5 to 10 times more than fenced, area. There little difference TC between two areas, but FS were higher reflected contributions wildlife. Recommended...

Abstract Crop residues (stover) have many potential uses by society: food, feed, shelter, fuel, and soil amendment. Use of for purposes other than as a amendment may serious negative consequences on crop productivity. This study was conducted to investigate the yield response continuous corn ( Zea mays L.) soybean [ Glycine max (L.) Merr.] removal or addition under no‐tillage management. The near Lincoln, NE, Crete‐Butler silty clay loam (fine, montmorillonitic, mesic Pachic...

Abstract The effects of corn residue on soil microbiological populations for dryland ( Zea mays L.) production in Nebraska were closely related to placement and water pH regimes. Populations bacteria, actinomycetes, fungi increased two‐ sixfold as a result mulching. response application was limited by competition from bacteria actinomycetes changes content Counts nitrifying denitrifying organisms the surface 2‐ 20‐fold 3‐ 43‐fold, respectively, plots receiving applications stover. physical,...

ABSTRACT: During the past decade, soil quality research and education programs have increased exponentially throughout world. Educational assessment approaches, ranging from simple scorecard test-kit monitoring to comprehensive quantitative assessments indexing using soils databases, been pursued. The emphasized that is not “an end in itself” but rather a tool for evaluating understanding effects of management on specific resource. approaches stressed determine how well functioning, inherent...

Understanding long‐term management effects on soil properties is necessary to determine the relative sustainability of cropping systems. Soil physical, chemical, and biological were measured in a system study Western Corn Belt. Properties evaluated after 16 yr four crop sequences [continuous corn ( zea mays L.) (CC), corn–soybean [Glycine max. (L.)] (C–SB), corn–oat Avena sativa + clover (80% sweet [ Melilotus officinalis L.] 20% red Trifolium pratense L.])–grain sorghum [( Sorghum bicolor...