• Authors:
    • Horfarter, R.
    • Hougaard, H.
    • Broge, N.
    • Knudsen, L.
    • Hansen, O. M.
    • Schelde, K.
    • Thomsen, A.
    • Berntsen, J.
  • Source: Precision Agriculture
  • Volume: 7
  • Year: 2006
  • Summary: Several methods were developed for the redistribution of nitrogen (N) fertilizer within fields with winter wheat (Triticum aestivum L.) based on plant and soil sensors, and topographical information. The methods were based on data from nine field experiments in nine different fields for a 3-year period. Each field was divided into 80 or more subplots fertilized with 60, 120, 180 or 240 kg N ha-1. The relationships between plot yield, N application rate, sensor measurements and the interaction between N application and sensor measurements were investigated. Based on the established relations, several sensor-based methods for within-field redistribution of N were developed. It was shown that plant sensors predicted yield at harvest better than soil sensors and topographical indices. The methods based on plant sensors showed that N fertilizer should be moved from areas with low and high sensor measurements to areas with medium values.The theoretical increase in yield and N uptake, and the reduced variation in grain protein content resulting from the application of the above methods were estimated. However, the estimated increases in crop yield, N-uptake and reduced variation in grain protein content were small.
  • Authors:
    • Hons, F.
    • Dou, F.
  • Source: Soil Science Society of America Journal
  • Volume: 70
  • Issue: 6
  • Year: 2006
  • Summary: Management practices that alter plant residue production and distribution influence SOC (soil organic carbon) dynamics. The objectives of this study were to investigate the impacts of tillage, cropping system, and N fertilizer application on SOC and soil N pools through physical fractionation of a central Texas soil after 20 years. Nitrogen fertilizer application and no-tillage (NT) significantly increased wheat ( Triticum aestivum) straw yield. Compared with conventional tillage (CT), SOC under NT in surface (0-5 cm) samples was 38, 69, and 68% greater for continuous wheat (CW), wheat-soyabean ( Glycine max)-sorghum ( Sorghum bicolor) rotation (SWS), and double-cropped wheat-soyabean (WS), respectively. The greatest SOC was observed in WS under NT with N fertilizer application, and the lowest occurred in CW under CT without N. Increased cropping intensity increased SOC compared with monoculture. Nitrogen fertilizer application only significantly increased SOC sequestration under NT. No-tillage increased SOC concentration in all physical size fractions compared with CT. Increased cropping intensity and N fertilizer application significantly increased SOC sequestration in most size fractions only under NT. Intraparticulate organic matter C (IPOM-C) was proportionally more affected by tillage than total SOC, indicating that this fraction was more sensitive to management. Carbon concentrations in all size fractions were significantly correlated with each other as well as SOC. Our results indicated that NT associated with enhanced cropping intensity and N fertilizer application sequestered greater SOC and soil total N.
  • Authors:
    • Derksen, D.
    • May, W.
    • Johnston, A.
    • Clayton, G.
    • Lafond, G.
    • Stevenson, F.
  • Source: Canadian Journal of Plant Science
  • Volume: 86
  • Issue: 2
  • Year: 2006
  • Summary: Surface residues and standing stubble protect soil against erosion and mitigate against crop water deficits by conserving additional moisture. However, residues and stubble can also present a dilemma for producers practising no-till in terms of nitrogen (N) fertilizer management and row spacing. The objective of this research was to determine how row spacing, N management using urea and two rates of post-emergent herbicide (66 and 100% of recommended) affect spring wheat establishment and plant development. The study was conducted using a no-till system and a canola-spring wheat cropping system at three locations over a 3-yr period. The N management and row spacing treatments were (1) 23-cm row spacing with fall banded N on 30 cm; (2) 23-cm row spacing with spring banded N on 30 cm; (3) 30-cm row spacing with the N side-banded; (4) 23-cm row spacing with the N side-banded; and (5) sweep on 23-cm spacing with seed and fertilizer scattered over a 20-cm width. Herbicide rates did not affect wheat development. Planting depth was greater for the sweep treatment, but only by 6 mm. Plant densities were at the low end of the optimal range of 200-250 plants m -2 for all treatments and were least for the 30 cm row spacing. Average frequencies for tillers T0, T1, T2 and T3 were 20, 81 61 and 10%, respectively. Fall and spring band treatments resulted in lower tiller frequencies than the sweep treatment, with intermediate levels for the side-band treatments. Tiller frequencies were identical between the 23-cm and 30-cm row spacings with N side-banded. Greater tiller frequencies for the sweep treatment likely resulted from the greater spread of seed, reducing inter-plant competition and closer proximity of the seed to fertilizer N. Spike density was not affected by N management. Expected spike density, calculated from tiller frequency and plant density data, was within 1% of the actual spikes recorded, when averaged over treatments. This means that tiller frequencies at the 5 to 5.5 leaf stage are a good predictor of expected spike density. Wider row spacings did not affect plant and tiller development but applying N fertilizer at time of seeding provided better spring wheat tiller development.
  • Authors:
    • Spera, S.
    • Lhamby, J.
    • Santos, H.
  • Source: Ciencia Rural
  • Volume: 36
  • Issue: 1
  • Year: 2006
  • Summary: A 6-year (1997/98-2002/03) study was undertaken in Passo Fundo, Rio Grande do Sul, Brazil, to assess the effects of soil tillage systems and crop rotation systems on soyabean grain yield and its components. The treatments comprised 4 soil tillage systems: (1) no-tillage, (2) minimum tillage in winter and no-tillage in summer, (3) conventional tillage with a disc plough in winter and no-tillage in summer, and (4) tillage using a mouldboard plough in winter and no-tillage in summer; and 3 crop rotation systems (I) wheat/soyabean, (II) wheat/soyabean and common vetch [ Vicia sativa]/maize or sorghum, and (III) wheat/soyabean, common vetch/maize or sorghum and white oats/soyabean. The yield and weight of 1000 kernels of soyabean grown under no-tillage and minimum tillage was higher than those grown under conventional soil tillage with a disc plough and a mouldboard plough. Plant height was greater in the no-tillage system. The yield of soyabean grown after wheat in system II was higher than in soyabean grown after white oats and wheat in system III and after wheat in system I. The lowest soyabean yield, grain weight per plant and weight of 1000 kernels were obtained in monoculture (wheat/soyabean).
  • Authors:
    • Avila, A.
    • Spera, S.
    • Lhamby, J.
    • Santos, H.
  • Source: Bragantia
  • Volume: 65
  • Issue: 4
  • Year: 2006
  • Summary: The effects of soil management system and winter crop rotation on wheat yield and root diseases were assessed. Four soil management systems: (1) no-tillage, minimum tillage, conventional tillage using a disc plough plus disc harrow, and conventional tillage using a mouldboard plough plus disc harrow; and 3 crop rotation systems: wheat/soyabean, wheat/soyabean and common vetch [ Vicia sativa]/maize or sorghum ( Sorghum bicolor), and wheat/soyabean, white oat/soyabean and common vetch/maize or sorghum, were compared. The yield and plant height of wheat grown under no-tillage and minimum tillage were higher than the yield of wheat grown under conventional soil tillage using either disk plough or mouldboard plough. Weight of 1000 kernels was highest in the no-tillage. Crop rotation was efficient in reducing root diseases and in increasing wheat yield. The lowest wheat yield, grain weight per plant, 1000-kernel weight and test weight were obtained in monoculture (wheat/soyabean).
  • Authors:
    • Sweeney, D.
    • Kilgore, G.
    • Whitney, D.
    • Schwab, G.
  • Source: Agronomy Journal
  • Volume: 98
  • Issue: 3
  • Year: 2006
  • Summary: Reduced- and no-tillage seedbed preparation methods coupled with broadcast P applications lead to an accumulation of available P in the surface 0- to 5-cm soil layer and a depletion of available P deeper in the profile. A 3-yr study determined the effects of tillage and fertilizer P management on P uptake and grain yield for P-stratified soils. Tillage practices were moldboard plow (once at the start of the study followed by reduced tillage), reduced tillage (disk followed by field cultivation), and no-tillage. Four P management methods were imposed: (i) no P; (ii) 20 kg P ha -1 applied as a surface broadcast; (iii) 20 kg ha -1 applied as a banded starter, 5 cm to the side and 5 cm below the seed; or (iv) 20 kg ha -1 applied in a deep placed band, 13 to 15 cm on 0.7-m centers. The one-time moldboard plowing produced higher early season dry matter yields for corn ( Zea mays L.), wheat ( Triticum aestivum L.), and soybean [ Glycine max (L.) Merr.] compared with the no-tillage system, but tillage effects on final grain yield were inconsistent. Subsurface placement of P generally increased P uptake and grain yield of corn and sorghum [ Sorghum bicolor (L.) Moench], but had little effect on grain yield of soybean. Results indicate that subsurface applications of P fertilizers should be considered if soil test P is highly stratified within the surface 0- to 15-cm layer and the 15-cm composite is medium or below for available P.
  • Authors:
    • Karamanos, R. E.
    • Malhi, S. S.
  • Source: Canadian Journal of Plant Science
  • Volume: 86
  • Issue: 3
  • Year: 2006
  • Summary: Deficiency of copper (Cu) in Canadian prairie soils is not widespread, but whenever it occurs it can cause a drastic reduction in seed yield and quality of most cereals, especially wheat. Field experiments conducted in western Canada indicated that broadcast-incorporation of granular Cu fertilizers prior to seeding at 3-5.6 kg Cu ha(-1) was usually sufficient to prevent Cu deficiency in wheat, and improve seed yield and quality. At lower rates ( (barley, alfalfa) > (timothy seed, oats, corn) > (peas, clovers) > (canola, rye, forage grasses). Stem melanosis in wheat was associated with deficiency of Cu in soil, and the disease was reduced substantially with Cu application. A high level of available P in soil was observed to induce/increase severity of Cu deficiency in wheat. Soil analysis for diethylene triamine pentacetic acid- (DTPA) extractable Cu in soil can be used as a good diagnostic tool to predict Cu deficiency, but there was a poor relationship between total Cu concentration in shoots and the degree of Cu deficiency in crops. Application of Cu fertilizers to wheat on Cu-deficient soils also generally improved seed quality.
  • Authors:
    • Prasad, J.
    • Challa, O.
    • Mandal, C.
    • Mandal, D. K.
  • Source: Agropedology
  • Volume: 16
  • Issue: 2
  • Year: 2006
  • Summary: The present study used water use efficiency (WUE) as an indicator of land quality index (LQI), through a composite Water Use Efficiency (GMWUE), on the line of land evaluation index of Food and Agriculture Organization. The GMWUE is a multiplicative function of WUE of individual crop/cropping system raised within a micro agro-edaphic environment (AEE). A relative LQI scale has been developed considering LQI for the most productive land as 100 and accordingly the LQI of other land has been fixed. The experimental cropping systems were cotton (sole), sorghum-wheat, soyabean-wheat, sorghum-gram and soyabean-gram for two years under normal rainfall in typical shrink-swell soils of Nagpur district of Maharashtra, India. The soyabean-wheat system had highest water use (WU) of 586.8 to 755.9 mm followed by sorghum-wheat, soyabean-gram, sorghum-gram and sole cotton. The WUE was highest for sole cotton (4.8-11.5 kg ha -1 mm -1) followed by soyabean-gram (3.7-10.16 kg ha -1 mm -1). The LQI in terms of GMWUE was 100 for Vertic Haplustepts occurring in the lower piedmont plain whereas it was 51 for Typic Haplustepts and 48 for Typic Haplusterts representing the upper piedmont and valley plain, respectively.
  • Authors:
    • Kumar, P.
    • Yadav, S. K.
    • Kumar, M.
    • Rinwa, R . S.
  • Source: Haryana Journal of Horticultural Sciences
  • Volume: 35
  • Issue: 3/4
  • Year: 2006
  • Summary: An experiment was conducted during 2003-04 and 2004-05 to study the nitrogen, phosphorus and potassium uptake by different cropping systems in semiarid tract of Haryana, India. The experiment comprised 7 cropping systems, viz., pearl millet-wheat, pearl millet-mustard, soyabean-wheat-cowpea, sorghum-wheat, pearl millet-potato-green gram, pearl millet-field pea-maize, and cotton-wheat. The uptake of nitrogen, phosphorus and potassium by the crops varied among different cropping systems. The nutrient uptake was higher in high yielding cropping systems. The nutrients uptake was highest in pearl millet-potato-green gram cropping system.
  • Authors:
    • Mason, H. E.
    • Spaner, D.
  • Source: Canadian Journal of Plant Science
  • Volume: 86
  • Issue: 2
  • Year: 2006
  • Summary: Wheat (Triticum aestivum L.) is the world's most widely grown crop, cultivated in over 115 nations. Organic agriculture, a production system based on reducing external inputs in order to promote ecosystem health, can be defined as a system that prohibits the use of synthetic fertilizers, chemical pesticides and genetically modified organisms. Organic agriculture is increasing in popularity, with a 60% increase in the global acreage of organically managed land from the year 2000 to 2004. Constraints that may be associated with organic grain production include reduced yields due to soil nutrient deficiencies and competition from weeds. Global wheat breeding efforts over the past 50 yr have concentrated on improving yield and quality parameters; in Canada, disease resistance and grain quality have been major foci. Wheat varieties selected before the advent of chemical fertilizers and pesticides may perform differently in organic, low-input management systems than in conventional, high-input systems. Height, early-season growth, tillering capacity, and leaf area are plant traits that may confer competitive ability in wheat grown in organic systems. Wheat root characteristics may also affect competitive ability, especially in low-input systems, and more research in this area is needed. The identification of a competitive crop ideotype may assist wheat breeders in the development of competitive wheat varieties. Wheat varieties with superior performance in low-input systems, and/or increased competitive ability against weeds, could assist organic producers in overcoming some of the constraints associated with organic wheat production.