Glomalin and Soil Aggregation under Six Management Systems in the Northern Great Plains, USA

The soil environment is linked to aboveground management including plant species composition, grazing intensity, levels of soil disturbance, residue management, and the length of time of a living plant is growing. Soil samples were collected under rangeland [native grass, rotational grazing (NGRG);tame grass, heavy grazing (TGRG);and tame grass, rotational grazing (TGHG)] and cropland [conventional till (CT);CT plus manure (CTM);and long term no till (NT)] systems. The rangeland systems were hypothesized to have higher glomalin content [measured as Bradford-reactive soil protein (BRSP)] and water stable aggregation (WSA) than the cropland systems. In addition, within both rangeland and cropland systems, BRSP and WSA were expected to decline with increased disturbance due to grazing or tillage and going from native to introduced plant species. Differences were detected for BRSP with NGRG and CTM having the highest values in range and cropland systems, respectively. However, the CTM system had higher BRSP values than one or both of the tame grass systems while the CT and NT systems had similar values. Correlation analysis showed strong relationships between all of the BRSP values and WSA.

Pasture-finishing of bison improves animal metabolic health and potential health-promoting compounds in meat

Background With rising concerns regarding the effects of red meat on human and environmental health,a growing number of livestock producers are exploring ways to improve production systems.A promising avenue includes agro-ecological practices such as rotational grazing of locally adapted ruminants.Additionally,growing consumer interest in pasture-finished meat(i.e.,grass-fed)has raised questions about its nutritional composition.Thus,the goal of this study was to determine the impact of two common finishing systems in North American bison—pasture-finished or pen-finished on concentrates for 146 d—on metabolomic,lipidomic,and fatty acid profiles of striploins(M.longissimus lumborum).Results Six hundred and seventy-one(671)out of 1570 profiled compounds(43%)differed between pasture-and penfinished conditions(n=20 animals per group)(all,P<0.05).Relative to pasture-finished animals,the muscle of pen-finished animals displayed elevated glucose metabolites(~1.6-fold),triglycerides(~2-fold),markers of oxidative stress(~1.5-fold),and proteolysis(~1.2-fold).In contrast,pasture-finished animals displayed improved mitochondrial(~1.3-fold higher levels of various Krebs cycle metabolites)and carnitine metabolism(~3-fold higher levels of long-chain acyl carnitines)(all P<0.05).Pasture-finishing also concentrated higher levels of phenolics(~2.3-fold),alpha-tocopherol(~5.8-fold),carotene(~2.0-fold),and very long-chain fatty acids(~1.3-fold)in their meat,while having lower levels of a common advanced lipoxidation(4-hydroxy-nonenal-glutathione;~2-fold)and glycation end-product(N6-carboxymethyllysine;~1.7-fold)(all P<0.05).In contrast,vitamins B5,B6,and C,gamma/beta-tocopherol,and three phenolics commonly found in alfalfa were~2.5-fold higher in pen-finished animals(all P<0.05);suggesting some concentrate feeding,or grazing plants rich in those compounds,may be beneficial.Conclusions Pasture-finishing(i.e.,grass-fed)broadly improves bison metabolic health and accumulates additional potential health-promoting compounds in their meat compared to concentrate finishing in confinement(i.e.,pen-finished).Our data,however,does not indicate that meat from pen-finished bison is therefore unhealthy.The studied bison meat—irrespective of finishing practice—contained favorable omega 6:3 ratios(<3.2),and amino acid and vitamin profiles.Our study represents one of the deepest meat profiling studies to date(>1500 unique compounds),having revealed previously unrecognized differences in animal metabolic health and nutritional composition because of finishing mode.Whether observed nutritional differences have an appreciable effect on human health remains to be determined.

Comparison of Net Global Warming Potential and Greenhouse Gas Intensity Affected by Management Practices in Two Dryland Cropping Sites

Little is known about the effect of management practices on net global warming potential (GWP) and greenhouse gas intensity (GHGI) that account for all sources and sinks of greenhouse gas (GHG) emissions in dryland cropping systems. The objective of this study was to compare the effect of a combination of tillage, cropping system, and N fertilization on GWP and GHGI under dryland cropping systems with various soil and climatic conditions from 2008 to 2011 in western North Dakota and eastern Montana, USA. Treatments in western North Dakota with sandy loam soil and 373 mm annual precipitation were conventional till malt barley (Hordeum vulgarie L.) with 67 kg N ha-1 (CTB/N1), conventional till malt barley with 0 kg N ha-1 (CTB/N0), no-till malt barley-pea (Pisum sativum L.) with 67 kg N ha-1 (NTB-P/N1), no-till malt barley with 67 kg N ha-1 (NTB/N1), and no-till malt barley with 0 kg N ha-1 (NTB/N0). In eastern Montana with loam soil and 350 mm annual precipitation, treatments were conventional till malt barley-fallow with 80 kg N ha-1 (CTB-F/N1), conventional till malt barley-fallow with 0 kg N ha-1 (CTB-F/N0), no-till malt barley-pea with 80 kg N ha-1 (NTB-P/N1), no-till malt barley with 80 kg N ha-1 (NTB/N1), and no-till malt barley with 0 kg N ha-1 (NTB/N0). Carbon dioxide sink as soil C sequestration rate at the 0 - 10 cm depth was greater in NTB-P/N1 and NTB/N1 than the other treatments at both sites and greater in eastern Montana than western North Dakota. Carbon dioxide sources were greater with N fertilization than without and greater with conventional till than no-till. Soil total annual N2O and CH4 fluxes varied among treatments, years, and locations. Net GWP and GHGI were lower in NTB-P/N1 than the other treatments in western North Dakota and lower in NTB-P/N1 and NTB/N1 than the other treatments in eastern Montana. Net GWP across similar treatments was lower in eastern Montana than western North Dakota, but GHGI was similar. Annualized crop yield was greater in the treatments with N fertilization than without. Because of greater grain yield but lower GWP and GHGI, no-till malt barley-pea rotation with adequate N fertilization can be used as a robust management practice to mitigate net GHG emissions while sustaining dryland crop yields, regardless of soil and climatic conditions. Loam soil reduced GWP and crop yields compared with sandy loam soil.

How profitable is switchgrass in Illinois, USA? An economic definition of marginal land

Background:Decisions regarding the conversion of land from an existing crop to bioenergy crops are critical for the sustainable production of both food and fuels.This study seeks to establish criteria for delineating land as“economically marginal”,and thus suited for growing switchgrass.Methods:In this case study of an Illinois agricultural field,the profitability of switchgrass,with farmgate prices of$44 Mg−1,$66 Mg−1,or$88 Mg−1,was compared to corn and soybean crop prices.Further,the study also evaluates the profitability of switchgrass when replacing corn‐based yield estimates from the Soil Productivity Index(SPI)of Illinois.Results:Based on a dry‐matter yield of 10.45 Mg ha−1,switchgrass can compete with soybeans only at the high price of$88 Mg−1,but depending on location,can compete with corn at$66 Mg−1.Across Illinois,at$88 ha−1,all Illinois land with SPI<100%and 95%of land under SPI class C(SPI 100–116)is profitable under switchgrass.Switchgrass may not be profitable relative to corn grown in the SPI class A(SPI>133)and only 7%of class B(SPI 117–132).Conclusions:Our results show that land with drainage and erosion limitations is economically marginal when corn and soybean yields are low,and the farmgate price for switchgrass is greater than$66 Mg−1.However,this may not be possible on land where switchgrass is replacing frequent soybean rotations(corn–soybean ratio≤1).Land used to produce only soybeans may only be marginal at the farmgate price of$88 Mg−1.Further studies need to be conducted to identify how much land can be converted to switchgrass without harming corn production.