• Authors:
    • Bortniak, M.
    • Goebiowska, H.
    • Weber, R.
  • Source: Journal of Plant Protection Research
  • Volume: 51
  • Issue: 4
  • Year: 2011
  • Summary: The objective of the study was to analyse the variability of the weed infestation of several winter wheat cultivars in relation to the soil tillage system applied and to the height of preceding crop stubble. The study was conducted in the years 2008-2010 in Lower Silesia, Poland. The following factors were studied in the experiment: factor I - stubble height a/ short stubble (10 cm) b/ tall stubble (40 cm); factor II - soil tillage systems a/ no-till b/ reduced tillage c/ conventional tillage - ploughing; factor III - winter wheat cultivars a/ Mewa, b/ Rapsodia, c/ Legenda. After the harvest of the preceding crop, glyphosate was sprayed on plots with short and tall stubble, in the first 10-days of August. The number of weeds on each analysed plot was estimated at random, with the frame method. For statistical analysis, the 8 most frequent weed species were selected: Viola arvensis, Sinapsis arvensis, Lamium purpureum, Veronica persica, Apera spica-venti, Capsella bursa-pastoris, Anthemis arvensis and Geranium pusillum. Based on the log-linear analysis, it was determined that V. arvensis and S. arvensis w ere the dominant weed species, whereas A. spica-venti and C. bursa-pastoris were characterised by significantly smaller numbers per 1 m 2. Significantly greater weed infestation was observed on plots with tall stubble. Increased weed infestation of winter wheat was noted in the reduced tillage treatments compared to those with conventional tillage. Only the numbers of S. arvensis were considerably lower under the conditions of no-till than in the conventional or reduced tillage systems. Cultivar Mewa limited the number of weeds per unit of area to a significant degree, while cv. Legenda increased weed infestation.
  • Authors:
    • Chen, G. H.
    • Khalilian, A.
    • Wiatrak, P.
  • Source: American Journal of Agricultural and Biological Sciences
  • Volume: 6
  • Issue: 1
  • Year: 2011
  • Summary: Problem statement: Insufficient rainfall under low yield environment may affect nitrogen management, plant growth indices and grain yields of corn ( Zea mays L.). Approach: The objective of this study was to determine the effects of two N application timings (all at planting and as split application with N applied at planting and V6 stage) and five N fertilizer rates (0, 45, 90, 135 and 180 kg N ha -1) on strip-tilled, dryland corn growth and yields under low-yield environmental conditions near Blackville SC, from 2007-2009. Plant growth measurements included plant height, ear height, relative chlorophyll content (SPAD), Leaf Area Index (LAI) and normalized difference vegetation index (NDVI). Results: Plant LAI at V8, NDVI at V8 and R1, SPAD at R1, plant height at V8 and grain yield generally increased with increasing N application rates. Due to most likely insufficient precipitation, the N application timing did not affect corn growth or yield. Despite relatively low grain yields, corn yield was increased by 1.6 Mg ha -1 with increasing N application rate of 100 kg ha -1. Grain yield was positively correlated with plant leaf area index (LAI) at R1 (r=0.27, p≤0.05) and Normalized Difference Vegetation Index (NDVI) at V8 and R1 (r=0.33 and 0.29, p≤0.01, respectively) and plant height at V8 stage (r=0.42, p≤0.001). With N applied at planting, there was a 0.55 and 0.49 Mg ha -1 yield increase with 0.1 increases in plant NDVI at V8 and R1, respectively. Conclusion: Under strip tillage and low yield environment conditions, plant growth and yields may not be affected by timing of N application mainly due to insufficient rainfall. Plant NDVI (for treatments with all N applied at planting) at V8 and R1 can help to estimate potential of corn grain yield, which may be reduced due to low nitrogen use efficiency.
  • Authors:
    • Corp, M.
    • Wuest, S.
  • Source: Crop Management
  • Issue: December
  • Year: 2011
  • Summary: Millions of acres of cropland with as low as 6 inches annual precipitation are used for production of winter wheat ( Triticum aestivum L.) in the Pacific Northwest of the USA. Despite soil conservation advances, soil erosion continues to be a problem. This on-farm study analyzed seed-zone soil water under farmer-implemented fallow tillage practices to find out if very low-disturbance systems are possible. A low-disturbance, wide-blade undercutter sweep treatment was similar or superior to the farmer's more intensive conventional tillage system. A subsequent test at four paired no-till-conventionally-tilled summer-fallow sites demonstrated that a single pass of an undercutter sweep in the no-till field could preserve seed-zone moisture comparable to the more intensive multiple-pass conventional tillage. Despite conventional wisdom, summer-fallow soil mulches do not need to be finely pulverized or repeatedly tilled to be effective.
  • Authors:
    • Schillinger, W.
    • Wuest, S.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Farmers in the low-precipitation (<300 mm annual) region of the Inland Pacific Northwest of the USA practice summer fallow to produce winter wheat ( Triticum aestivum L.) in a 2-yr rotation. No-till fallow (NTF) is ideal for wind erosion control but is not widely practiced because of seed-zone soil drying during the summer, whereas adequate seed-zone water for germination and emergence of deep-sown winter wheat can generally be retained with tilled fallow (TF). Successful establishment of winter wheat from late August- early September planting is critical for optimum grain yield potential. A 6-yr field study was conducted to determine if accumulations of surface residue under long-term NTF might eventually be enough to substitute for TF in conserving seed-zone water over summer. Averaged over the 6 yr, residue rates of 1500, 6000, and 10 500 kg ha -1 (1*, 4*, and 7* rates, respectively) on NTF produced incrementally greater seed-zone water but were not capable of conserving as much as TF. Total root zone (0-180 cm) over-summer water loss was greatest in the 1 * NTF whereas there were no significant differences in the 4* and 7* NTF versus TF. Average precipitation storage efficiency ranged from 33% for 1* NTF to 40% for TF. We conclude that for the low-precipitation winter wheat-summer fallow region of the Inland Pacific Northwest: (i) Cumulative water loss during the summer from NTF generally exceeds that of TF; (ii) there is more extensive and deeper over-summer drying of the seed-zone layer with NTF than with TF; (iii) increased quantities of surface residue in NTF slow the rate of evaporative loss from late-summer rains, and (iv) large quantities of surface residue from April through August will marginally enhance total-profile and seed-zone water in NTF, but will not retain adequate seed-zone water for early establishment of winter wheat except sometimes during years of exceptionally high precipitation or when substantial rain occurs in mid-to-late August.
  • Authors:
    • Li, Z.
    • Liu, W. Z.
    • Zhang, X. C.
    • Chen, J.
  • Source: Agricultural and Forest Meteorology
  • Volume: 151
  • Issue: 10
  • Year: 2011
  • Summary: Trends and uncertainty of the climate change impacts on hydrology, soil erosion, and wheat production during 2010-2039 at El Reno in central Oklahoma, USA, were evaluated for 12 climate change scenarios projected by four GCMs (CCSR/NIES, CGCM2, CSIRO-Mk2, and HadCM3) under three emissions scenarios (A2, B2, and GGa). Compared with the present climate, overall t-tests ( n=12) show that it is almost certain that mean precipitation will decline by some 6% (>98.5% probability), daily precipitation variance increase by 12% (>99%), and maximum and minimum temperature increase by 1.46 and 1.26 degrees C (>99%), respectively. Compared with the present climate under the same tillage systems, it is very likely (>90%) that evapotranpiration and long-term soil water storage will decease, but runoff and soil loss will increase despite the projected declines in precipitation. There will be no significant changes in wheat grain yield. Paired t-tests show that daily precipitation variance projected under GGa is greater than those under A2 and B2 ( P=0.1), resulting in greater runoff and soil loss under GGa ( P=0.1). HadCM3 projected greater mean annual precipitation than CGCM2 and CSIRO ( P=0.1). Consequently, greater runoff, grain yield, transpiration, soil evaporation, and soil water storage were simulated for HadCM3 ( P=0.1). The inconsistency among GCMs and differential impact responses between emission scenarios underscore the necessity of using multi-GCMs and multi-emission scenarios for impact assessments. Overall results show that no-till and conservation tillage systems will need to be adopted for better soil and water conservation and environmental protection in the region during the next several decades.
  • Authors:
    • Dube, R. K.
    • Dhyani, S. K.
    • Sharma, A. R.
    • Ratan, S.
  • Source: Indian Journal of Agricultural Sciences
  • Volume: 81
  • Issue: 4
  • Year: 2011
  • Summary: A field experiment was conducted at Selakui, Dehradun during 2001-04 to study the effect of tillage (conventional and minimum) and mulching practices (no mulching and live mulching) under artificially created varying land slopes (0.5, 2.5, 4.5 and 9.5%) on soil-moisture conservation, productivity and nutrient uptake in maize ( Zea mays L.)-wheat ( Triticum aestivum L. emend Fiori & Paol.) cropping system. Sunnhemp ( Crotalaria juncea L.) intercropped with maize gave 0.87-1.09 tonnes biomass (dry weight) and accumulated 24.8-31.4 kg N/ha at 30 days of growth when it was mulched. Biomass and N accumulation generally decreased with increasing land slope and under minimum tillage. Maize performed better on moderate slopes (2.5-4.5%) than on the relatively flat (0.5%) and highly sloping land (9.5%). However, the yield of wheat decreased linearly and significantly with increasing slope due to less conservation of soil moisture on sloping lands during the previous rainy season. Conventional tillage gave significantly higher productivity of both maize and wheat than the minimum tillage. Intercropping of maize with sunnhemp and spreading the cut biomass as mulch at 30 days (live mulching) improved soil moisture conservation at maize harvest (+1.63 to 1.94%), and yield of maize (12.0%) as well as of following wheat (13.8%) compared with the no mulching.
  • Authors:
    • Navarrete, L.
    • Kozak, M.
    • Hernandez Plaza, E.
    • Gonzalez-Andujar, J. L.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 140
  • Issue: 1-2
  • Year: 2011
  • Summary: This study investigated whether the choice of a tillage system (no-tillage, minimum tillage or traditional tillage) affected weed diversity in a 23 years cereal-leguminous rotation system in Spain. Weed diversity was assessed using common diversity indices: species richness, Shannon's index and Pielouis evenness. Linear mixed-effects models were employed to compare the tillage systems. It was found that after 23 years no large differences between tillage systems have arisen related to weed diversity. Only minimum tillage appeared to support, on average, more species than the two other tillage systems. Richness, Shannon diversity index and evenness varied largely through the years in all tillage systems but this variation was not related to type of crop sown (cereal or leguminous). Our results highlight that conservation tillage practices did not represent any concern for weed diversity conservation in cereal-leguminous rotations in the conditions of central Spain.
  • Authors:
    • Stevenson, F. C.
    • Legere, A.
    • Benoit, D. L.
  • Source: Weed Science
  • Volume: 59
  • Issue: 1
  • Year: 2011
  • Summary: A conservation tillage study provided the opportunity to test whether tillage effects on the germinable weed seedbank would be consistent across different crop rotations and to investigate the potential residual effects of herbicide treatments terminated 12 yr earlier. Our objective was to measure the effects of tillage (moldboard plow [MP] vs. chisel plow [CP] vs. no-till [NT]), crop rotation (2-yr barley-red clover followed by 4-yr barley-canola-wheat-soybean rotation, compared to a cereal monoculture), and of a prior weed management factor (three intensity levels of herbicide use) on the density, diversity, and community structure of weed seedbanks. Species richness, evenness (Shannon's E), and diversity (Shannon's H′) of spring seedbanks varied little across treatments and over time. Total seedbank density generally increased as tillage was reduced, with some variations due to weed management in 1993 and crop rotation in 2006. Crop rotations generally had smaller seedbanks with fewer species than the monoculture. In 1993, seedbanks with minimum weed management were twice as dense as those with intensive or moderate weed management (approximately 6,000 vs. 3,000 seed m -2). By 2006, seed density averaged 6,838 seed m -2 across intensive and moderate weed management regardless of tillage, but was nearly twice as large in NT (12,188 seed m -2) compared to MP (4,770 seed m -2) and CP (7,117 seed m -2) with minimum weed management (LSD 0.005=4488). Species with abundant seedbanks responded differently to treatments. Barnyardgrass and green foxtail had larger seedbanks in the monoculture than in the rotation. Common lambsquarters and pigweed species had large seedbanks in tilled treatments in the rotation, whereas yellow foxtail and field pennycress contributed to the large seedbanks observed in NT treatments. The latter two species were also associated with residual effects of weed management treatments (terminated 12 yr earlier) in NT. The differential seedbank response of weed species, attributed in part to contrasting weed emergence patterns and agronomic practice effects on seed rain, explained some of the weak treatment effects observed for total seedbank density and diversity. The large weed seedbanks observed in NT plots after 18 yr confirms the importance of seed rain and seedbank management for the sustainability of NT systems.
  • Authors:
    • Officer, S. J.
    • Kelly, K.
    • Kearney, G. A.
    • Graham, J. F.
  • Source: Annual Meeting of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America
  • Year: 2011
  • Authors:
    • Kiese, R.
    • Butterbach-Bahl, K.
    • Reeves, S. H.
    • Dalal, R. C.
    • Wang, W.
  • Source: Global Change Biology
  • Volume: 17
  • Issue: 10
  • Year: 2011