261. Effects of hedgerows and ridge cultivation on losses of nitrogen and phosphorus of slope land in Three Gorges Reservoir area.

• Authors:
  • Li, Y.
  • Liu, G.
  • Yang, L.
  • Ma, L.
  • Xia, L.
• Source: Transactions of the Chinese Society of Agricultural Engineering
• Volume: 28
• Issue: 14
• Year: 2012
• Summary: Protective management of arable slope land plays an important role in protection of land resource and aquatic environment in Three Gorges region, China. Base on the regional natural conditions and the utilization of the arable slope land, four tillage modes with H1 (rotation of wheat and maize, wheat intercropped with horse bean, less tillage and ridge cultivation), H2 (rotation of wheat and maize, with Vetiveria ziz anioides contour hedges intercropped at slop length interval of 5 m), H3 (rotation of wheat and maize, with alfalfa contour hedges intercropped at slop length interval of 5 m), H4 (rotation of wheat and maize, conventional management) were conducted from Oct. 2009 to Oct. 2011. The differences of apparent recovery efficiency and Agronomic efficiency of applied nitrogen and phosphorus between treatments were discussed, as well as nitrogen and phosphorus losses through slope land surface runoff were analyzed. The results showed that compared with H4, H1 increased phosphorus use efficiency by 0.06 kg/kg. No significant difference of biological and economic production, apparent recovery efficiency and agronomic efficiency of applied nitrogen and phosphorus was observed among H2, H3 and H4, which showed intercropping with Vetiveria ziz anioides or alfalfa contour hedges wouldn't lead to the reduction of production. Furthermore significant effects on reducing soil erosion and sediment phosphorus loss were observed for H1, H2 and H3. Compared with H4, and sediment losses for H1, H2 and H3 decreased by 48.46%, 52.26% and 58.59% respectively, and sediment phosphorus losses decreased by 30.58%, 47.70% and 44.58% respectively.

262. Variability of retention process of isoxaflutole and its diketonitrile metabolite in soil under conventional and conservation tillage.

• Authors:
  • Bergheaud, V.
  • Benoit, P.
  • Alletto, L.
  • Coquet, Y.
• Source: Pest Management Science
• Volume: 68
• Issue: 4
• Year: 2012
• Summary: BACKGROUND: Sorption largely controls pesticide fate in soils because it influences its availability for biodegradation or transport in the soil water. In this study, variability of sorption and desorption of isoxaflutole (IFT) and its active metabolite diketonitrile (DKN) was investigated under conventional and conservation tillage. RESULTS: According to soil samples, IFT KD values ranged from 1.4 to 3.2 L kg -1 and DKN KD values ranged from 0.02 to 0.17 L kg -1. Positive correlations were found between organic carbon content and IFT and DKN sorption. IFT and DKN sorption was higher under conservation than under conventional tillage owing to higher organic carbon content. Under conservation tillage, measurements on maize and oat residues collected from the soil surface showed a greater sorption of IFT on plant residues than on soil samples, with the highest sorbed quantities measured on maize residues ( KD ~45 L kg -1). Desorption of IFT was hysteretic, and, after five consecutive desorptions, between 72 and 89% of the sorbed IFT was desorbed from soil samples. For maize residues, desorption was weak (

263. Chemical properties of a Humic Dystrudept after 12 years under conventional and no tillage with crop succession and rotation.; Atributos quimicos de um Cambissolo Humico apos 12 anos sob preparo convencional e semeadura direta em rotacao e sucessao de culturas.

• Authors:
  • Albuquerque, J.
  • Picolla, C.
  • Mafra, A.
  • Andrade, A.
  • Bertol, I.
• Source: Ciencia Rural
• Volume: 42
• Issue: 5
• Year: 2012
• Summary: Suitable soil management is one of the bases for sustainability in agricultural systems. The study aimed to evaluate chemical properties of a Humic Dystrudept for 12 years under two tillage systems, with crops rotation and succession. The experiment was carried out in Lages, SC, under conventional tillage (CT) and no-till (NT), with rotation (r) and succession (s) cropping systems, using crop sequences of beans-fallow-maize-fallow-soybean in CTr; maize-fallow in CTs; beans-oats-maize-fodder radish-soybean-vetch in NTr; and maize-vetch in NTs. The experimental design was completely randomized with four replicates. The soil samples were collected in the layers 0-2.5, 2.5-5, 5-10 and 10-20 cm. The variables assessed were total organic carbon (TOC), calcium, magnesium, exchangeable aluminum, phosphorus, potassium, total nitrogen (TN) and water pH. The no-tillage system increased TOC and nutrient levels in comparison with conventional tillage, especially in the surface soil layer. Maize and vetch crop succession had higher TOC and TN contents in the surface soil layer compared to crop rotation under no-tillage.

264. Soil microbial biomass under different tillage and levels of applied pig slurry.

• 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.

265. Crop rotation effect on soil carbon and Nitrogen stocks under limited irrigation.

• Authors:
  • Schlegel, A.
  • Halvorson, A.
• Source: Agronomy Journal
• Volume: 104
• Issue: 5
• Year: 2012
• Summary: Limited irrigation management practices are being used in the Central Great Plains to conserve water by optimizing crop water use efficiency. Limited irrigation may reduce total crop biomass production and amount of crop residue returned to the soil. Crop residue production within four no-till (NT) crop rotations [continuous corn ( Zea mays L.) (CC); corn-winter wheat ( Triticum aestivum L.) (CW); corn-winter wheat-grain sorghum ( Sorghum bicolor L. Moench) (CWS); corn-winter wheat-grain sorghum-soybean [ Glycine max (L.) Merr.] (CWSSb)] was measured and changes in soil organic carbon (SOC) and total soil nitrogen (TSN) stocks were monitored for 10 yr. Crop residue yields varied with crop being produced and with rotation, as did residue N and C returned to the soil. The C/N ratio of the residue varied with crop. The SOC and TSN pools increased with time in all rotations. The rate of gain in SOC and TSN mass for each rotation was 717, 477, 335, and 270 kg SOC ha -1 yr -1 and 114, 92, 87, and 84 kg TSN ha -1 yr -1 for the CC, CW, CWS, and CWSSb rotations, respectively, in the 0- to 30.5-cm soil depth. The rate of change in SOC and TSN mass was lowest with CWSSb (8.7 Mg residue ha -1 yr -1) and highest with CC (12.0 Mg residue ha -1 yr -1). Approximately 6.8 to 7.6 Mg residue ha -1 yr -1 would be needed to maintain SOC stocks under limited irrigation.

266. Soil quality indicators at the Riberao Extrema watershed, Distrito Federal: Part II.; Indicadores de qualidade dos solos na microbacia do Ribeirao Extrema, Distrito Federal: Parte II.

• Authors:
  • Neumann, M.
  • Lacerda, M.
  • Lago, W.
• Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
• Volume: 16
• Issue: 7
• Year: 2012
• Summary: The intensively increasing agricultural use of Distrito Federal soils may compromise their quality and trigger environmental problems in the region. Given this fact, the objective of this work was to study the soil quality (SQ) indicators, in areas under no tillage (PD), with diversified managements (corn-soybean rotation and bean-sorghum succession), at the Riberao Extrema watershed, Distrito Federal. Soil bulk density (Ds), flocculation index (GF), organic matter (MO), cation exchange capacity (CTC), microbial respiration (Rmic) and microbial biomass carbon (Cmic) were the attributes of SQ evaluated. Statistical analysis was performed using the statistical software Statistics Analysis System (SAS) and consisted of analysis of variance (ANOVA) followed by Tukey test for comparison of means. Results show that some of the evaluated SQ indicators were affected by different types of soil management under evaluation (Ds, Cmic and MO), while others were not sensitive to them (GF, CTC and Rmic). Positive correlation was found between MO and CTC of the soils in both investigated treatments, highlighting the importance of no tillage system on the chemical properties of soil.

267. No tillage in rainfed Aragon (NE Spain): effect on organic carbon in the soil surface horizon.

• Authors:
  • Limon, M.
  • Blanco-Moure, N.
  • Lopez, M.
  • Gracia, R.
• Source: Soil & Tillage Research
• Volume: 118
• Year: 2012
• Summary: Conservation tillage has been encouraged as a management alternative to preserve soil and water resources in semiarid Aragon (NE Spain). In fact, its adoption by farmers, and especially of no tillage (NT) systems, has increased in recent years. However, little information concerning the soils on which these techniques are applied is available for this region. The objective of this study was to assess the potential of NT to increase organic carbon content at the soil surface (0-20 cm) in rainfed Aragon. To this aim, 22 pairs of adjacent farm fields under NT and conventional tillage (CT) were compared in different cereal production areas. The fields were under continuous NT between 5 and 19 years but half were over 10 years. Soil organic carbon (SOC) in NT ranged from 7.06 to 18.53 g kg -1 (0-20 cm depth) and was higher than 12 g kg -1 in nearly 30% of the fields. These contents represented between 8% less (only one case) and 55% more SOC under NT than under CT with an average gain of 20% in favour of NT. The highest SOC contents were found in the NT fields of longer duration (>10 years) and/or managed with practices that enhance the return of more crop biomass to the soil (complete residue return, cropping intensification and manure application). The identification of the current management practices used by farmers has allowed us to know the diversity of the NT-based cropping systems and the reality of the conservation agriculture in our region. Overall, results from this on-farm study indicate that NT can be recommended as a viable alternative to CT to increase organic carbon at the soil surface in cereal production areas of Aragon.

268. Dryland soil nitrogen cycling influenced by tillage, crop rotation, and cultural practice.

• 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.

269. Long-term no tillage increased soil organic carbon content of rain-fed cereal systems in a Mediterranean area.

• Authors:
  • Jones, J.
  • Porter, C.
  • Orsini, R.
  • Seddaiu, G.
  • Roggero, P.
  • Sanctis, G.
• Source: European Journal of Agronomy
• Volume: 40
• Year: 2012
• Summary: The differential impact on soil organic carbon (SOC) of applying no tillage (NT) compared to conventional tillage (CT, i.e. mouldboard ploughing), along with three rates of nitrogen (N) fertilizer application (0, 90 and 180 kg ha -1 y -1), was studied under rain-fed Mediterranean conditions in a long-term experiment based on a durum wheat-maize rotation, in which crop residues were left on the soil (NT) or incorporated (CT). Observed SOC content following 8 and 12 years of continuous treatment application was significantly higher in the top 10 cm of the soil under NT than CT, but it was similar in the 10-40 cm layer. NT grain yields for both maize and durum wheat were below those attained under CT (on average 32% and 14% lower respectively) at a given rate of N fertilizer application. Soil, climate and crop data over 5 years were used to calibrate DSSAT model in order to simulate the impact of the different management practices over a 50-year period. Good agreement was obtained between observed and simulated values for crops grain yield, above-ground biomass and observed SOC values. Results from the simulations showed that under NT the weeds growing during the intercrop fallow period made a significant contribution to the observed SOC increase. When the contribution of the weed fallow was considered, NT significantly increased SOC in the top 40 cm of the soil at an average rate of 0.43, 0.31 and 0.03 t ha -1 per year, respectively for 180, 90 and 0 kg N ha -1 year -1, within the simulated 50 years. Under CT, a significant SOC increase was simulated under N180 and a significant decrease when no fertilizer was supplied.

270. Interactive effects of plants and earthworms on the physical stabilization of soil organic matter in aggregates

• Authors:
  • Velasquez, E.
  • Quintero, D. C.
  • Fonte, S. J.
  • Lavelle, P.
• Source: PLANT AND SOIL
• Volume: 359
• Issue: 1-2
• Year: 2012
• Summary: Plants and earthworms are key ecosystem engineers and important regulators of soil aggregation and C dynamics, yet research to date has mainly considered their impacts in isolation thereby ignoring potential interactions between these organisms. We conducted a microcosm experiment under greenhouse conditions to assess the impacts of plants (Brachiaria decumbens) and earthworms (Pontoscolex corethrurus) on soil structure and C stabilization. Aggregate stability was assessed by wet-sieving. Large macroaggregates (> 2 mm) were also visually separated according to origin (e.g., earthworms, roots) and then further fractionated into particle size fractions to assess aggregate composition and C distribution. Earthworms increased aboveground biomass of B. decumbens by nearly 30 %. The presence of plant roots increased aggregate stability (mean weight diameter) by 2.6 %. While earthworms alone had no simple impacts on aggregation, a significant interaction revealed that earthworms increased aggregate stability in the presence of roots by 6 % when compared to microcosms without plants. Additionally, the presence of roots increased the C concentration of coarse particulate organic matter in earthworm casts, while earthworms increased C storage in microaggregates and the silt and clay fraction within root-derived aggregates. These findings suggest that plants and earthworms are intimately linked in soil aggregate formation and that both organisms need be considered simultaneously for proper management of soils.