• Authors:
    • Matos, M.
    • Machineski, O.
    • Balota, E.
  • Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
  • Volume: 16
  • Issue: 5
  • Year: 2012
  • Summary: The objective of this work was to evaluate the changes in microbial biomass C, N and P due to the application of pig slurry under different soil tillage systems. The experiment was established in a clayey Oxisol, Eutrophic Red Latossol in Palotina, PR. Different quantities of pig slurry (0, 30, 60 and 120 m 3 ha -1 year -1) were applied to the soil prior to the summer and winter crop season under conventional tillage (CT) and no tillage (NT), in three replicates. The area was cultivated with soybean ( Glycine max L.) or maize ( Zea mays L.) in the summer and wheat ( Triticum sativum Lam.) or oat ( Avena sativa L.) in the winter. The soil samples were collected in March and October of 1998 and 1999 at depths of 0-5, 5-10 and 10-20 cm. The soil tillage and pig slurry application influenced the microbial biomass C, N and P. The microbial biomass and the microbial activity presented high sensibility to detect changes in the soil due to tillage and the application of pig slurry. The soil microbial biomass and C mic/C org relation increased as the quantity of applied pig slurry increased. The metabolic quotient under CT increased with depth while under NT it decreased. The soil microbial biomass was enriched in N and P under NT and as the quantity of applied pig slurry increased.
  • Authors:
    • Hirata, T.
    • Komatsuzaki, M.
    • Nakamoto, T.
    • Araki, H.
  • Source: Soil Science and Plant Nutrition
  • Volume: 58
  • Issue: 1
  • Year: 2012
  • Summary: We hypothesized that cover cropping could increase soil microbial activities under various tillage systems and that increased microbial activities would improve soil properties. Soil sampling was conducted at two fields in Japan in 2009. At the Ibaraki field (Andosol, clay loam), three tillage practices (no-tillage, plowing to 30 cm, and rotary tillage to 15 cm) and three types of winter cover cropping [bare fallow as control, hairy vetch ( Vicia villosa Roth), and rye ( Secale cereale L.)] were conducted from 2003 to 2009. At the Hokkaido field (Fluvisol, light clay), two tillage practices (autumn tillage and rotary tillage with a rotary tiller to a depth of 15 cm once in autumn and twice in a year, respectively), and four types of winter cover cropping (bare fallow, hairy vetch, bristle oat ( Avena strigosa L.), and a mixture of hairy vetch and bristle oat) were conducted from 2006 to 2009. Soil microbial activities and the fungal-to-bacterial activity ratio (F/B ratio) were estimated by the substrate-induced respiration (SIR) method with the use of selective antibiotics. At the Ibaraki field, rye cover cropping showed higher microbial SIR than bare fallow at depths of 0-30 cm and rotary tillage maintained higher microbial SIR than no-tillage or plowing at depths of 7.5-15 cm. There was no meaningful interaction effect between cover cropping and tillage on microbial SIR. At the Hokkaido field, cover cropping and tillage had only limited effects on microbial SIR. High F/B ratios (indicating fungal dominance) were recorded with the use of cover crops in both fields. Fungal SIR, estimated from the microbial SIR and F/B ratio, was closely related to the content of total soil organic carbon (SOC) and the mean weight diameter (MWD) of water-stable aggregates. Based on SOC, fungal SIR was significantly higher under rye cover cropping. The relationship between fungal SIR and MWD was affected by tillage. We conclude that rye cover cropping and rotary tillage were very effective in increasing fungal SIR, SOC, and MWD in the Ibaraki soil. Field practices that enhance fungal activities might be effective in improving certain types of arable soil.
  • Authors:
    • Lartey, R.
    • Jabro, J.
    • Caesar-Tonthat, T.
    • Lenssen, A.
    • Sainju, U.
    • Evans, R.
    • Allen, B.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 93
  • Issue: 3
  • Year: 2012
  • Summary: Management practices may influence dryland soil N cycling. We evaluated the effects of tillage, crop rotation, and cultural practice on dryland crop biomass (stems and leaves) N, surface residue N, and soil N fractions at the 0-20 cm depth in a Williams loam from 2004 to 2008 in eastern Montana, USA. Treatments were two tillage practices (no-tillage [NT] and conventional tillage [CT]), two crop rotations (continuous spring wheat [ Triticum aestivum L.] [CW] and spring wheat-barley [ Hordeum vulgaris L.] hay-corn [ Zea mays L.]-pea [ Pisum sativum L.] [W-B-C-P]), and two cultural practices (regular [conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height] and ecological [variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height]). Nitrogen fractions were soil total N (STN), particulate organic N (PON), microbial biomass N (MBN), potential N mineralization (PNM), NH 4-N, and NO 3-N. Crop biomass N was 30% greater in W-B-C-P than in CW in 2005. Surface residue N was 30-34% greater in NT with the regular and ecological practices than in CT with the regular practice. The STN, PON, and MBN at 10-20 and 0-20 cm were 5-41% greater in NT or CW with the regular practice than in CT or CW with the ecological practice. The PNM at 5-10 cm was 22% greater in the regular than in the ecological practice. The NH 4-N and NO 3-N contents at 10-20 and 0-20 cm were greater in CT with W-B-C-P and the regular practice than with most other treatments in 2007. Surface residue and soil N fractions, except PNM and NO 3-N, declined from autumn 2007 to spring 2008. In 2008, NT with W-B-C-P and the regular practice gained 400 kg N ha -1 compared with a loss of 221 kg N ha -1 to a gain of 219 kg N ha -1 in other treatments. No-tillage with the regular cultural practice increased surface residue and soil N storage but conventional tillage with diversified crop rotation and the regular practice increased soil N availability. Because of continuous N mineralization, surface residue and soil N storage decreased without influencing N availability from autumn to the following spring.
  • Authors:
    • Kaiser, D. E.
    • Sheaffer, C. C.
    • Russelle, M. P.
    • Coulter, J. A.
    • Yost, M. A.
  • Source: AGRONOMY JOURNAL
  • Volume: 104
  • Issue: 4
  • Year: 2012
  • Summary: Compared with corn ( Zea mays L.) following corn, N guidelines for first-year corn following alfalfa ( Medicago sativa L.) in the U.S. Corn Belt suggest that N rates can be reduced by about 168 kg N ha -1 when ≥43 or 53 alfalfa plants m -2 are present at termination. These guidelines have been questioned by practitioners, however, as corn grain yields have increased. We conducted experiments at 16 locations in Minnesota to address questions regarding N availability to first-year corn after alfalfa relating to the effect of carryover fertilizer K from alfalfa and the amount and timing of alfalfa regrowth incorporation. Corn grain yield, silage yield, and fertilizer N uptake were not affected by carryover K or amount or timing of regrowth incorporation. Maximum corn grain yield ranged from 12.0 to 16.1 Mg ha -1 among locations but responded to fertilizer N at only one. At that location, which had inadequate soil drainage, the economically optimum N rate (EONR) was 85 kg N ha -1, assuming prices of US$0.87 kg -1 N and US$132 Mg -1 grain. The EONR for silage yield across 6 of 15 locations where it was measured was 40 kg N ha -1, assuming US$39 Mg -1 silage. These results demonstrate that on highly productive medium- to fine-textured soils in the Upper Midwest with ≥43 alfalfa plants m -2 at termination, first-year corn grain yield is often maximized without fertilizer N, regardless of alfalfa regrowth management or timing of incorporation, but that small N applications may be needed to optimize silage yield.
  • Authors:
    • Cantero-Martínez, C.
    • Arrúe, J. L.
    • Plaza-Bonilla, D.
    • Morell, F. J.
    • Álvaro-Fuentes, J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 120
  • Year: 2012
  • Summary: Agricultural management plays an important role in global warming mitigation due to its effects on soil organic carbon (SOC) dynamics. In Mediterranean agroecosystems, the interactive effects of tillage and N fertilization on SOC storage have scarcely been studied. Hence, we here present a modelling study in which the effects of both tillage and N fertilization on SOC dynamics are investigated. We used SOC and C input data from a long-term (13 years) field study located in northeast Spain, firstly to validate both the Century model and the Rothamsted Carbon (RothC) model and secondly to predict future SOC dynamics until the year 2030. Tillage and N fertilization affected SOC stocks in the 0-30cm soil layer. However, the interaction of the two factors was not significant. Averaged over the three N fertilization rates, the observed mean SOC stocks in conventional tillage (CT) and no-tillage (NT) were 29.8 and 36.8MgCha -1, respectively. In addition, the observed SOC stocks, averaged for both tillage systems, increased with increasing N rates, with 30.6, 33.5 and 35.8MgCha -1 for the 0, 60 and 120kgNha -1 rates, respectively. In general, both the Century model and the RothC model performed well in predicting SOC dynamics. Model predictions showed that in Mediterranean dryland agroecosystems SOC dynamics in the next 20 years would be variable according to the tillage and N fertilization applied. According to these predictions, scenarios with NT and high fertilization rates (e.g., 60-120kgNha -1) could lead to significant SOC sequestration and associated CO 2 emission offsetting. However, these scenarios with high SOC sequestration rates also showed high mineral N accumulation in the soil profile with its associated environmental side effects. © 2012 Elsevier B.V..
  • Authors:
    • Bauer, S.
    • Das, R.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 121
  • Year: 2012
  • Summary: Soil degradation is a major threat to agricultural sustainability in Nepal. Increased anthropogenic activities in the inherently fragile ecosystem of unstable geology, steep slopes and intense monsoon rains have accelerated the loss of soil and its fertility in the Nepalese hills. This paper assesses soil conservation technologies from biophysical and economic perspectives using the integrated bio-economic analysis. The study applied a biophysical model, Soil Change Under Agroforestry (SCUAF), to project effects of the conservation technologies on soil erosion control as well as on crop yields over a thirty-year period. The technologies considered are hedgerow intercropping and minimum tillage. The outcome of the biophysical model was integrated into a cost-benefit analysis to examine the economic viability of the technologies. The results showed that these technologies are effective in reducing a substantial rate of soil erosion prevailing in the conventional system of maize cultivation. They have a variable impact on yield maintenance and the farmers' economic return over time. The hedgerow intercropping sustained crop yields in the long-term although yield was reduced in the short-term. Likewise, high costs for establishing and maintaining the hedgerow intercropping significantly reduced farmers' economic returns in the short-term. Minimum tillage technology, while better than the conventional farming system, was not able to sustain crop yield in the long-term. Yet, it provided positive returns for a longer period than the conventional system. The study concludes that though the evaluated technological options are effective in reducing the high rate of erosion resulting from the conventional maize cropping system, economically they are not viable for farmers in the short-term. Therefore, to expedite the wider adoption of these technologies and to halt and reverse soil degradation, it is suggested that farmers initially be supported with economic incentives to compensate their short-term economic loss. © 2012 Elsevier B.V.
  • Authors:
    • González-Prieto, S. J.
    • Couto-Vázquez, A.
    • Gómez-Rey, M. X.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 124
  • Year: 2012
  • Summary: The effect of 14-years of plough and conservation tillage on macro- and micro-nutrient availability and on N transformation rates was evaluated in a temperate humid region soil (0-5 and 5-15cm) under an annual Italian ryegrass-maize forage rotation. Nutrients were extracted with an NH 4Ac-DTPA solution. Gross N mineralization (m), nitrification (n) and immobilization (i) rates were calculated by 15N isotope dilution technique (experiment with 15NH 4, 48-h incubation) with the FLUAZ model. Our results demonstrate that long-term conservation tillage increases organic C in the upper soil layer and the availability of most of studied nutrients (Co, Fe, Mg, Mn, Na, P and Zn) compared with plough tillage. On the contrary, conservation tillage resulted in lower contents of NO 3 --N, and extractable K and Mn in the 5-15cm soil layer. Extractable Al, Ca and Cu were unaffected by tillage system or soil depth. No significant effect of tillage practices on gross and net N transformation rates was observed. Soil C contents was not related to gross and net N fluxes, while positive relationships were found between: (1) m and soil available NH 4 +-N; (2) n and soil available K and d 15N; (3) i and soil available K, Mn, Mg, total N and NO 3 --N; and (4) net m and n with soil available NO 3 --N and K. The negative relationships of n and d 15N with soil Co content suggested that Co availability could affect the nitrifying activity. Results suggest that tillage practices had a limited effect on N transformation rates in this soil and that NO 3 --N leaching could decrease under conservation tillage. For N fluxes in these agricultural soils, K was a more important factor than the other nutrients, suggesting close relationships between N and K availability; however, some micro-nutrients could also play a relevant role on soil N cycle and, therefore, they must be considered in future studies on gross N fluxes. © 2012 Elsevier B.V.
  • Authors:
    • Fleige, H.
    • Zink, A.
    • Hartmann, P.
    • Horn, R.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 124
  • Year: 2012
  • Summary: In this study we determined wheeling (external loads of 6.3. Mg by 10 times wheeling) and tillage effects (conventional and conservation tillage) on the soil hydraulic properties of Stagnic Luvisols in Northwest Germany and modeled the soil water balance's reaction on both loading and changing climatic conditions. Due to the mechanical stress applied by loading, physical properties changed distinctly in the top Ap-horizons and the subsequent Eg-horizons at both tillage systems. Especially pore size distributions and soil hydraulic conductivities were affected. The Btg horizons did not show changes due to loading. Soil water balance was measured with soil tensiometers during one growing period and the following autumn and was modeled with Hydrus 1D for loaded and unloaded conditions under winter wheat for three different periods (1991-2000; 2051-2060; 2091-2100) based on a regional A1B climate scenario. At the loaded sites we found an increase of actual transpiration rates in the growing period. As a consequence of stronger drying and changed hydraulic properties, rewetting in autumn and winter was retarded and less complete on average. Furthermore, simulations indicated an increase of the variability of matric potentials. Consequently, compaction might result in a higher drought risk and a higher susceptibility for water logging in spring, which may result in less favorable soil conditions and plant growth. Reactions of soil water balance on changing climatic conditions were comparable for all loading variants and tillage systems. Predicted changes in precipitation (in general: summer -, winter +) and temperature (+) would result in a reduction of transpiration rates in the growing period while the climatic water balance in autumn and winter would increase distinctly. © 2012 Elsevier B.V.
  • Authors:
    • Labrecque, M.
    • Guidi, W.
    • Lockwell, J.
  • Source: PLANT AND SOIL
  • Volume: 360
  • Issue: 1-2
  • Year: 2012
  • Summary: We carried out a paired-site study (Melanic Brunisol) to assess the impact on soil carbon stocks of land-use change following establishment and multiple rotations of willows (Salix miyabeana SX67) in short-rotation coppice (SRWC). Total soil organic carbon (TSOC), hot-water extractable carbon (HWC) and amino sugars (AS) were used as main parameters of soil carbon dynamic. We found that the establishment event and 2 years of growth under SRWC did not result in any change in the TSOC pool or in the HWC pool. However, we found an increase in AS at and near the soil surface (0-20 cm) of the establishing willow plantations. We related this to the effect of the green manure applied before planting. After multiple rotations of SRWC, we found a redistribution of TSOC in the vertical profile (0-40 cm) but no TSOC difference compared to previous land-use (abandoned alfalfa crop). In the subsoil (20-40 cm), we found indications that the more labile soil organic carbon (SOC) pools were depleted (HWC and muramic acid). Willow plantations on Melanic Brunisol in southern Quebec (Canada) represent, over the long-term, a soil carbon sink when replacing a short-term no-till crop rotation. However, the conversion from abandoned alfalfa fields into SRWC does not apparently enhance soil carbon potential sequestration.
  • Authors:
    • Madejón, E.
    • Deurer, M.
    • López-Garrido, R.
    • Murillo, J. M.
    • Moreno, F.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 118
  • Year: 2012
  • Summary: Long-term field experiments are important to provide information about how soil carbon (C) dynamics is affected by soil tillage systems. In this study we directly diagnose the influence of the topsoil's (0-5cm depth) C concentration on soil quality in an Entisol under Mediterranean conditions, testing a new statistical method. The objective was to estimate the impact of conservation tillage (RT) as a C management practice, versus a traditional tillage (TT) system on biophysical soil properties. We analyzed the impact of the soil C management on biological (microbial biomass C, dehydrogenase and ß-glucosidase activities), physical soil properties (aggregates stability, conductive mean pore diameter, aggregation index) and CO 2 fluxes. The concentrations for total organic carbon (TOC), the active carbon (AC) normalised by the total carbon (AC TOC -1), served as a combined proxy for the soil C management related to the tillage system. Soil C management accounted for 0-46% of the change of biophysical soil properties in RT versus TT. The RT led to a C increase (18.9%) of microbial activities, especially in the top 0-5cm depth. Related to the physical soil properties, less C in TT led to a lower aggregation index, although this tendency was not observed for other physical parameters. The impact of soil C management was better correlated with soil microbial than with the physical properties. Our analysis directly quantified for the first time that the increase in the soil's carbon concentration could only explain a small fraction of the beneficial change in biophysical soil properties due to RT. In general the RT contributed to the long-term sustainability of the agroecosystem by improving biological and physical soil characteristics under dryland semi-arid Mediterranean conditions.