Microbial biomass and N cycling under native prairie, conservation reserve and no-tillage in Palouse soils

Purakayastha, T. J.; Smith, Jeffery L.; Huggins, David R.

doi:10.1016/j.geoderma.2009.06.013

Cited by 23 publications

(14 citation statements)

References 54 publications

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“…Among the cultivated treatments, the increase in MBC under reduced tillage systems compared to FP is attributed to greater C source availability (POM-C, POXC, and WEOC) and favorable soil environmental conditions for microbial activity (Wardle, 1992;Purakayastha et al, 2009). Crop residue accumulation at the soil surface not only provided organic C substrates for microbial biomass, but reduced soil disturbance likely favored the formation of stable soil aggregates that protected microbial biomass against soil temperature and water fluctuations (Collins et al, 1992;Franzluebbers et al, 1995;Balota et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Soil Organic Carbon Pools as Early Indicators for Soil Organic Matter Stock Changes under Different Tillage Practices in Inland Pacific Northwest

2017

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Soil organic matter (SOM) is essential for sustaining soil health and crop productivity. However, changes in SOM stocks in response to agronomic practices are slow and show years later when it is too late for adjustments in management. Identifying early indicators of SOM dynamics will allow early management decisions and quick remedial action. The objectives of this study were to evaluate long-term effects of tillage intensity and timing on SOM pools and determine the most responsive SOM pools to tillage practice. Soil from a long-term (53 years) winter wheat (Triticum aestivum L.)-spring pea (Pisum sativum L.) rotation and undisturbed grass pasture (GP) in inland Pacific Northwest (iPNW) was sampled to evaluate the effect of four tillage systems [no-till (NT), disk/chisel (DT/CT), spring plow (SP), and fall plow (FP)] on soil organic carbon (SOC, proxy for SOM), total nitrogen (TN), particulate organic matter carbon (POM-C) and nitrogen (POM-N), permanganate oxidizable carbon (POXC), water extractable organic carbon (WEOC), total dissolved nitrogen (TDN), KCl-extractable nitrogen (KEN), microbial biomass carbon (MBC) and nitrogen (MBN), basal respiration (BR), carbon mineralization (Cmin), and metabolic quotient (qCO 2 ). GP had higher levels of SOC pools than cultivated treatments. On average, tillage significantly decreased SOC and TN by 28 and 26%, respectively, compared to GP. Among the cultivated soils, tillage had no significant effect on SOC and TN, except for DT/CT that had slightly higher SOC than FP (P = 0.08). On the contrary, NT and DT/CT significantly (P < 0.05) increased levels of POM-C, POM-N, POXC, WEOC, MBC, BR, Cmin, and qCO 2 over FP or SP. However, tillage did not affect TDN, MBN, and KEN. The C-pools (POM-C, POXC, MBC, WEOC, BR, and Cmin) were more strongly correlated with SOM than the N-pools (TDN, MBN, and KEN), with an exception to POM-N. Under wheat-pea rotation in the iPNW, reduced tillage systems (NT and DT/CT) have a potential to maintain or increase SOM, which can be assessed early through its physical (POM), chemical (POXC, WEOC), and microbiological (MBC, BR, Cmin) indicators. POXC and WEOC were the most sensitive indicators of tillage-induced changes in SOM dynamics.

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Section: Discussionmentioning

confidence: 99%

Soil Organic Carbon Pools as Early Indicators for Soil Organic Matter Stock Changes under Different Tillage Practices in Inland Pacific Northwest

2017

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“…Total soil C and N were determined on air-dried soil sieved to 2.0 mm and subsequently roller-ground to a fine powder (Purakayastha et al, 2009). The analysis was performed by dry combustion using a CHN autoanalyzer (LECO CHN-1000, Leco Corp., St Joseph, MI, USA; Tabatabai and Bremner, 1970).…”

Section: Soil Carbon and Nitrogen Fractionationmentioning

confidence: 99%

Climate Change Predicted to Negatively Influence Surface Soil Organic Matter of Dryland Cropping Systems in the Inland Pacific Northwest, USA

2017

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Soil organic matter (SOM) is a key indicator of agricultural productivity and overall soil health. Currently, dryland cropping systems of the inland Pacific Northwest (iPNW) span a large gradient in mean annual temperature (MAT) and precipitation (MAP). These climatic drivers are major determinants of surface SOM dynamics and storage characteristics. Future climate change projections through 2070 indicate significant shifts in MAT and MAP for the iPNW. We assessed surface (0-10 cm) soil organic C and N as well as active and recalcitrant fractions of SOM within long-term experiments representing different tillage regimes and cropping intensities across the current climatic gradient of the iPNW. We discovered that current levels of soil C and N as well as various SOM fractions were positively correlated with MAP and negatively correlated with MAT. Furthermore, these climatic drivers were more influential than either tillage regime or cropping intensity in determining SOM levels and characteristics. Soil organic C and total N as well as the hydrolyzable and non-hydrolyzable fractions were negatively correlated with the current ratio of MAT to MAP, called the climate ratio. Future climate projections (2030 and 2070) forecast an increase of the climate ratio, thus predicting declines in surface SOM and associated soil health across the iPNW.

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“…2), consistent with its high SOM content, microbial activity, and contributions from root respiration. Native grassland soils have been shown to possess greater labile C pools, microbial biomass and activities and, therefore, greater respiration than no-till and conventionally tilled soils (Carpenter-Boggs et al, 2003;Purakayastha et al, 2009). The similarity in CO 2 fluxes among the fertilized and unfertilized STNT and LTNT soils reflects the comparable SOM levels and microbial activity among them.…”

Section: Soil Co 2 -And N 2 O-flux Datamentioning

confidence: 99%

The effect of nitrogen fertilization and no‐till duration on soil nitrogen supply power and post–spring thaw greenhouse‐gas emissions

Hangs

Schoenau

Lafond

2013

Z. Pflanzenernähr. Bodenk.

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With a world population now > 7 billion, it is imperative to conserve the arable land base, which is increasingly being leveraged by global demands for producing food, feed, fiber, fuel, and facilities (i.e., infra-structure needs). The objective of this study was to determine the effect of varying fertilizer-N rates on soil N availability, mineralization, and CO 2 and N 2 O emissions of soils collected at adjacent locations with contrasting management histories: native prairie, short-term (10 y), and long-term (32 y) no-till continuous-cropping systems receiving five fertilizer-N rates (0, 30, 60, 90, and 120 kg N ha -1 ) for the previous 9 y on the same plots. Intact soil cores were collected from each site after snowmelt, maintained at field capacity, and incubated at 20°C for 6 weeks. Weekly assessments of soil nutrient availability along with CO 2 and N 2 O emissions were completed. There was no difference in cumulative soil N supply between the unfertilized longterm no-till and native prairie soils, while annual fertilizer-N additions of 120 kg N ha -1 were required to restore the N-supplying power of the short-term no-till soil to that of the undisturbed native prairie soil. The estimated cumulative CO 2 -C and N 2 O-N emissions among soils ranged from 231.8-474.7 g m -2 to 183.9-862.5 mg m -2 , respectively. Highest CO 2 fluxes from the native prairie soil are consistent with its high organic matter content, elevated microbial activity, and contributions from root respiration. Repeated applications of ≥ 60 kg N ha -1 resulted in greater residual inorganic-N levels in the long-term no-till soil, which supported larger N 2 O fluxes compared to the unfertilized control. The native prairie soil N 2 O emissions were equal to those from both short-and long-term no-till soils receiving repeated fertilizer-N applications at typical agronomic rates (e.g., 90 kg N ha -1 ). Eighty-eight percent of the native soil N 2 O flux was emitted during the first 2 weeks and is probably characteristic of rapid denitrification rates during the dormant vegetative period after snowmelt within temperate native grasslands. There was a strong correlation (R 2 0.64; p < 0.03) between measured soil Fe-supply rate and N 2 O flux, presumably due to anoxic microsites within soil aggregates resulting from increased microbial activity. The use of modern no-till continuous diversified cropping systems, along with application of fertilizer N, enhances the soil N-supplying power over the long-term through the build-up of mineralizable N and appears to be an effective management strategy for improving degraded soils, thus enhancing the productive capacity of agricultural ecosystems. However, accounting for N 2 O emissions concomitant with repeated fertilizer-N applications is imperative for properly assessing the net global warming potential of any land-management system.

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Microbial biomass and N cycling under native prairie, conservation reserve and no-tillage in Palouse soils

Cited by 23 publications

References 54 publications

Soil Organic Carbon Pools as Early Indicators for Soil Organic Matter Stock Changes under Different Tillage Practices in Inland Pacific Northwest

Soil Organic Carbon Pools as Early Indicators for Soil Organic Matter Stock Changes under Different Tillage Practices in Inland Pacific Northwest

Climate Change Predicted to Negatively Influence Surface Soil Organic Matter of Dryland Cropping Systems in the Inland Pacific Northwest, USA

The effect of nitrogen fertilization and no‐till duration on soil nitrogen supply power and post–spring thaw greenhouse‐gas emissions

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