• Authors:
    • Benjamin, J. G.
    • Nielsen, D. C.
    • Vigil, M. F.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 2
  • Year: 2011
  • Summary: No-till dryland winter wheat ( Triticum aestivum L.)-fallow systems in the central Great Plains have more water available for crop production than the traditional conventionally tilled winter wheat-fallow systems because of greater precipitation storage efficiency. That additional water is used most efficiently when a crop is present to transpire the water, and crop yields respond positively to increases in available soil water. The objective of this study was to evaluate yield, water use efficiency (WUE), precipitation use efficiency (PUE), and net returns of cropping systems where crop choice was based on established crop responses to water use while incorporating a grass/broadleaf rotation. Available soil water at planting was measured at several decision points each year and combined with three levels of expected growing season precipitation (70, 100, 130% of average) to provide input data for water use/yield production functions for seven grain crops and three forage crops. The predicted yields from those production functions were compared against established yield thresholds for each crop, and crops were retained for further consideration if the threshold yield was exceeded. Crop choice was then narrowed by following a rule which rotated summer crops (crops planted in the spring with most of their growth occurring during summer months) with winter crops (crops planted in the fall with most of their growth occurring during the next spring) and also rotating grasses with broadleaf crops. Yields, WUE, PUE, value-basis precipitation use efficiency ($PUE), gross receipts, and net returns from the four opportunity cropping (OC) selection schemes were compared with the same quantities from four set rotations [wheat-fallow (conventional till), (WF (CT)); wheat-fallow (no-till), (WF (NT)); wheat-corn ( Zea mays L.)-fallow (no-till), (WCF); wheat-millet ( Panicum miliaceum L.) (no-till), (WM)]. Water use efficiency was greater for three of the OC selection schemes than for any of the four set rotations. Precipitation was used more efficiently using two of the OC selection schemes than using any of the four set rotations. Of the four OC cropping decision methods, net returns were greatest for the method that assumed average growing season precipitation and allowed selection from all possible crop choices. The net returns from this system were not different from net returns from WF (CT) and WF (NT). Cropping frequency can be effectively increased in dryland cropping systems by use of crop selection rules based on water use/yield production functions, measured available soil water, and expected precipitation.
  • Authors:
    • Mendes, I.
    • de Castro Lopes, A.
    • Nunes, R.
    • Gomes de Sousa, D.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 4
  • Year: 2011
  • Summary: MANAGEMENT SYSTEMS AND THE CARBON AND NITROGEN STOCKS OF CERRADO OXISOL UNDER SOYBEAN-MAIZE SUCCESSION Carbon and N stocks in soils are determined by the balance between addition and losses, and tillage and cropping systems are decisive in this process. This study aimed to evaluate the effect of soil management systems based on tillage, cover crops and P fertilization on C and N stocks in physical fractions of the soil organic matter and on microbial biomass and respiration in a soil after 11 years under soybean-maize rotation. The experiment was initiated in 1999 in an Oxisol with adequate level of available P to obtain form 80 to 90 % of potential yields of annual crops. The experiment was arranged in a split-plot design in randomized blocks, with three management systems based on soil tillage and cover crop (conventional tillage with pearl millet, no-tillage with pearl millet and no-tillage with velvet bean) assigned to the main plots and two P levels (0 and 100 kg ha(-1) yr(-1) of P2O5 as triple superphosphate applied at sowing) in subplots. Soil samples were collected at the grain filling stage of soybean (March 2010), from the soil layers 0-5, 5-10 and 10-20 cm, and subjected to physical fractionation of organic matter and microbial analysis. The no-tillage system resulted in stratification of organic C and N while conventional tillage resulted in a more homogeneous distribution in the 0-20 cm layer. Phosphorus fertilization for 11 years led to an accumulation of organic C and N in the soil, regardless of tillage and cover crop systems. Higher stocks of organic C and total N, higher microbial biomass C and lower microbial respiration were found under no-tillage than conventional tillage, both with pearl millet as cover crop. In the no-tillage systems, greater stocks of organic C and total N, similar microbial biomass C and higher microbial respiration were found with pearl millet as cover crop compared to velvet bean. The conversion rate of C added by crops to soil organic C was 4.0, 8.2 and 14.3 % for conventional tillage with pearl millet and no-tillage with pearl millet and with velvet bean, respectively.
  • Authors:
    • Obi,M. E.
    • Obalum, S. E.
    • Wakatsuki, T.
    • Amalu, U. C.
  • Source: Experimental Agriculture
  • Volume: 47
  • Issue: 1
  • Year: 2011
  • Summary: Over a decade after the forest-savanna transition zone of Nigeria was deemed suitable for production of sorghum (Sorghum bicolor), no research has been undertaken on the crop's tillage requirements in the southeastern part of the zone. This study evaluated the effects of tillage-mulch practices on soil moisture, water use (WU), grain yield and water use efficiency (WUE) of the crop in a Typic Paleustult (sandy loam) at Nsukka during 2006 and 2007 growing seasons. In a split-plot design, no-till (NT) and conventional tillage (CT) treatments were left bare (B) or covered with mulch (M) at 5 Mg ha(-1). The ensuing treatments (NTB, NTM, CTB, and CTM) represented four tillage methods, which were replicated four times in a randomized complete block. In the monitored root. zone, NTB and CTM significantly (p <= 0.05) enhanced the soil moisture status over NTM and CTB, but the main effects of the tillage and the mulch factors were not significant. The crop WU was uninfluenced by the treatments throughout the study Although the grain yield showed higher values with NT than with CT, the differences were significant (p <= 0.05) only in 2007 that was marked with erratic rainfall and relatively low mean yield. Mulch significantly (p <= 0.05) enhanced the grain yield in 2006, with greater effect in CT than NT On average, the mulch plots out-yielded their bare counterparts by about 26%. The tillage x mulch interaction was significant (p <= 0.01), and showed higher grain yields in NTB, NTM and CTM than in CTB. In the year-weighted average, yield increments in NTB, NTM and CTM over CTB were 53, 53 and 67% respectively, a pointer to the relevance of mulch with the CT but not the NT. Relative WU showed that the crop's water demand was met under all treatments. Hence, the yield reduction in the CTB was not due to water shortage. The WUE varied among the treatments in the same pattern as grain yield. In summary, NTB and CTM proved superior to NTM only in soil moisture status but to CTB in all measured parameters. From a socio-economic viewpoint, however, NTB would be preferable to CTM for growing sorghum in this area.
  • Authors:
    • Wakatsuki, T.
    • Obi, M.
    • Okpara, I.
    • Obalum, S.
  • Source: Tropical and Subtropical Agroecosystems
  • Volume: 14
  • Issue: 2
  • Year: 2011
  • Summary: A key indicator of soil quality as organic carbon needs to be enhanced in the highly weathered soils predominant in southeastern Nigeria through appropriate tillage-mulch practices and cropping systems. We subjected a degraded Typic Paleustult (sandy loam) at Nsukka to no-till (NT) and conventional tillage (CT) and bare fallow (B) and mulch cover (M). This was duplicated with one sole-cropped to sorghum and the other to soybean as separate crop treatments during 2006 and 2007 growing seasons. The CT resulted in higher available P (P av) (under soybean) and cation exchange capacity (CEC) (under both crops) than the NT. Mulch gave lower P av under sorghum and vice versa under soybean. Exchangeable Ca was lowered while exchangeable acidity was enhanced with mulch under soybean. Overall, soil organic carbon and exchangeable Mg, Na and acidity were enhanced under soybean relative to sorghum; the reverse was the case for P av. However, the soil's CEC indicated comparable values in both cropping systems. Our results suggest that cropping 'CT with M' soil to soybean could be a promising agronomic combination for enhancing the SOC and fertility status of the soil.
  • Authors:
    • Smith, D. R.
    • Gal, A.
    • Vyn, T. J.
    • Omonode, R. A.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: Few experiments have directly compared the long-term effects of moldboard, chisel, and no-till tillage practices on N 2O emissions from the predominant crop rotation systems in the midwestern United States. This study was conducted from 2004 to 2006 on a tillage and rotation experiment initiated in 1975 on a Chalmers silty clay loam (a Typic Endoaquoll) in west-central Indiana. Our objectives were to assess (i) long-term tillage (chisel [CP], moldboard plow [MP], and no-till [NT]), rotation (continuous corn [ Zea mays L.] and corn-soybean [ Glycine max (L.) Merr.]), and rotation * tillage interaction effects on soil N 2O emission, and (ii) how soil N 2O emission is related to environmental factors during corn production under identical N fertilizer management. Seasonal N 2O emissions were measured at intervals ranging from a few days to biweekly for up to 14 sampling dates in each growing season for corn. Nitrous oxide emissions during the growing season were significantly affected by tillage and rotation but not their interaction; however, 50% of total emissions occurred shortly after N application regardless of tillage or rotation practices. Seasonal cumulative emissions were significantly lower under NT but not statistically different for CP and MP. Overall, emissions under NT were about 40% lower relative to MP and 57% lower relative to CP. Rotation corn lowered N 2O emissions by 20% relative to continuous corn. Higher N 2O emission under MP and CP appeared to be driven by soil organic C decomposition associated with higher levels of soil-residue mixing and higher soil temperatures.
  • Authors:
    • Petersen, S. O.
    • Mutegi, J. K.
    • Hansen, E. M.
    • Munkholm, L. J.
  • Source: Soil Biology and Biochemistry
  • Volume: 43
  • Issue: 7
  • Year: 2011
  • Summary: Conservation tillage practices are widely used to protect against soil erosion and soil C losses, whereas winter cover crops are used mainly to protect against N losses during autumn and winter. For the greenhouse gas balance of a cropping system the effect of reduced tillage and cover crops on N2O emissions may be more important than the effect on soil C. This study monitored emissions of N2O between September 2008 and May 2009 in three tillage treatments, i.e., conventional tillage (CT), reduced tillage (RI) and direct drilling (DD), all with (+CC) or without (-CC) fodder radish as a winter cover crop. Cover crop growth, soil mineral N dynamics, and other soil characteristics were recorded. Furthermore, soil concentrations of N2O were determined eight times during the monitoring period using permanently installed needles. There was little evidence for effects of the cover crop on soil mineral N. Following spring tillage and slurry application soil mineral N was dominated by the input from slurry. Nitrous oxide emissions during autumn, winter and early spring remained low, although higher emissions from +CC treatments were indicated after freezing events. Following spring tillage and slurry application by direct injection N2O emissions were stimulated in all tillage treatments, reaching 250-400 mu g N m(-2) h(-1) except in the CT + CC treatment, where emissions peaked at 900 mu g N M-2 h(-1). Accumulated emissions ranged from 1.6 to 3.9 kg N2O ha(-1). A strong positive interaction between cover crop and tillage was observed. Soil concentration profiles of N2O showed a significant accumulation of N2O in CT relative to RI and DD treatments after spring tillage and slurry application, and a positive interaction between slurry and cover crop residues. A comparison in early May of N2O emissions with flux estimates based on soil concentration profiles indicated that much of the N2O emitted was produced near the soil surface.
  • Authors:
    • Raus, L.
    • Jitareanu, G.
    • Ailincai, C.
  • Source: Lucrari Stiintifice, Universitatea de Stiinte Agricole Si Medicina Veterinara "Ion Ionescu de la Brad" Iasi, Seria Agronomie
  • Volume: 54
  • Issue: 2
  • Year: 2011
  • Summary: The experiment was conducted at the Didactic Station of the "Ion Ionescu de la Brad" University of Agricultural Sciences and Veterinary Medicine of Iasi, Ezareni Farm, during farming years 2007-2009. The experimental site is located in the East part of Romania on a chambic chernozem, with a clay-loamy texture, 6.8 pH units, 3.7% humus content and a medium level of fertilization. The soil has high clay content (38-43%) and is difficult to till when soil moisture is close to the wilting point (12.2%). We have investigated three variants of soil tillage system - conventional tillage, minimum tillage and no-till - in the crop rotation made of wheat and raps. This paper presents the results obtained in winter rape growing as concerns the influence of the tillage method on some soil physical characteristics and yield. Research carried out aimed at developing fundamental knowledge through in-depth inquiries of soil quality indicators of Moldavian Plain, regarding integrated management of soil and water. Research carried out also aimed to quantify the influence of agricultural technologies on physic, hydric, thermic, nutrient and biological soil regime, and ecological impact of these changes on ecological, energetically, hydrological, biogeochemical and breathing soil function, in specific areas of Moldavian Plain. Tillage system modify, at least temporarily, some of the physical properties of soil, such as soil bulk density, penetration resistance, soil porosity and soil structural stability. All the tillage operation was significantly different in their effects on soil properties. The results indicate that soil tillage systems must be adjusted to plant requirements for crop rotation and to the pedoclimatic conditions of the area.
  • Authors:
    • Bahrami, H.
    • Roozbeh, M.
    • Sheikhdavoodi, M. J.
    • Almassi, M.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 23
  • Year: 2011
  • Summary: Degradation of agricultural soils and nutrient losses affected by intensive agriculture and tillage is of environmental and agricultural concerns. These concerns lead to emergence and development of conservative technologies such as conservation tillage systems [reduced tillage (RT) and no-till (NT)] and anionic polyacrylamide (PAM). A study was done in order to investigate the interactive effects of three tillage systems and three PAM concentration on sediment loss, runoff nitrate concentration, nitrogen losses from the soil-plant system and nitrogen recovery. The experimental design was a randomized complete block with split-plot arranged in three replications. The anionic polyacrylamide (PAM) were in three levels of zero (P0), 10 (P10) and 20 (P20) mg L -1 as the main plot and different tillage intensities as the subplot including moldboard plowing plus two disk harrow passes (CT1), one stubble cultivator pass (RT) and moldboard plowing plus one power harrow pass (CT2). The RT treatment relative to CT2 led to soil loss reduction by 23.56% during the first irrigation. The P10 and P20 treatments relative to P0, caused sediment concentration reduction by 98.1 and 98.09% and soil loss reduction by 98.7% and 98.8%, respectively. The RT * P20 treatment had a greater impact in reduction runoff nitrate losses than CT1 * P20 and CT2 * P20 treatments. Losses of N in the fertilized plots and recovery of applied N (RAN) was influenced by both tillage system and PAM application.
  • Authors:
    • Ryan, J.
    • Kapur, S.
    • Ibrikci, H.
    • Singh, M.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: As most of the organic carbon (C) in the biosphere resides in the soil in the form of soil organic matter (SOM), tillage practices can potentially increase C losses to the atmosphere as carbon dioxide, thus contributing to greenhouse gases that exacerbate climate change. In the past century, conventional tillage, involving plowing and secondary cultivation, has unwittingly decreased C stocks in arable soils in North America, Europe, and Australia. The information on the effects of tillage on soil C and related properties in the Mediterranean region is scant, with evidence of resilience being even rarer. While long-term trials that directly measure tillage effects are rare in the Mediterranean, the alternative is a retrospective based on soil management history. In this study of a Vertisol in southern Turkey, we sampled sections of a field that had been intensively cultivated for about 20 years and 40 years, as well as a section left undisturbed in native vegetation for 14 years following years of conventional tillage. The SOM and total nitrogen (N) values were inversely related to cultivation intensity or duration, while the highest values were from the uncultivated site. Labile biomass C and N values followed the same trends with cultivation, whereas available P increased with cultivation time; in contrast, the percentage of water-stable aggregates decreased with cultivation duration. The study showed that such clay soils show a high degree of resilience and can recover in a relatively short time period if left uncultivated or in fallow. While preservation or set aside of arable crop land is not a viable option for farmers, reducing tillage intensity is feasible. The study suggests that minimum tillage or no-till could promote resilience and mitigate the adverse soil effects of conventional tillage that have already occurred.
  • Authors:
    • Jabro, J. D.
    • Lartey, R. T.
    • Evans, R. G.
    • Allen, B. L.
    • Sainju, U. M.
    • Lenssen, A. W.
    • Caesar-TonThat, T.
  • Source: Plant and Soil
  • Volume: 338
  • Issue: 1-2
  • Year: 2011
  • Summary: Novel management practices are needed to increase dryland soil organic matter and crop yields that have been declining due to long-term conventional tillage with spring wheat ( Triticum aestivum L.)-fallow system in the northern Great Plains, USA. The effects of tillage, crop rotation, and cultural practice were evaluated on dryland crop biomass (stems+leaves) yield, surface residue, and soil organic C (SOC) and total N (STN) at the 0-20 cm depth in a Williams loam (fine-loamy, mixed, superactive, frigid, Typic Argiustolls) from 2004 to 2007 in eastern Montana, USA. Treatments were two tillage practices [no-tillage (NT) and conventional tillage (CT)], four crop rotations [continuous spring wheat (CW), spring wheat-pea ( Pisum sativum L.) (W-P), spring wheat-barley ( Hordeum vulgaris L.) hay-pea (W-B-P), and spring wheat-barley hay-corn ( Zea mays L.)-pea (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)]. Crop biomass and N content were 4 to 44% greater in W-B-C-P than in CW in 2004 and 2005 and greater in ecological than in regular cultural practice in CT. Soil surface residue amount and C and N contents were greater in NT than in CT, greater in CW, W-P, and W-B-C-P than in W-B-P, and greater in 2006 and 2007 than in 2004 and 2005. The SOC and STN concentrations at 0-5 cm were 4 to 6% greater in CW than in W-P or W-B-P in NT and CT from 2005 and 2007. In 2007, SOC content at 10-20 cm was greater in W-P and W-B-P than in W-B-C-P in CT but STN was greater in W-B-P and W-B-C-P than in CW in NT. From 2004 to 2007, SOC and STN concentrations varied at 0-5 cm but increased at 5-20 cm. Diversified crop rotation and delayed planting with higher seed rates and banded N fertilization increased the amount of crop biomass returned to the soil and surface residue C and N. Although no-tillage increased surface residue C and N, continuous nonlegume cropping increased soil C and N levels at the surface layer compared with other crop rotations. Continued return of crop residue from 2004 to 2007 may increase soil C and N levels but long-term studies are needed to better evaluate the effect of management practices on soil C and N levels under dryland cropping systems in the northern Great Plains.