• Authors:
    • Feltran, J. C.
    • De Castro, C. M.
    • De Almeida, D. L.
    • Valle, Teresa L.
    • Duarte Ribeiro, R. De L.
    • Pries Devide, A. C.
  • Source: Bragantia
  • Volume: 68
  • Issue: 1
  • Year: 2009
  • Summary: Organic systems were evaluated for cassava root production directed to human comsumption in natura, at Seropedica-RJ. Treatments consisted of: cassava ('IAC 576-70') in single cropping and its intercropping with corn ('Eldorado'), cowpea ('Maua') or corn plus cowpea. The organic management was standardized and the experimental area was submitted to artificial irrigation during the period of stay of maize in the system. "Green" (immature) corn ears were harvested at the "point" required for fresh marketing and the shoot placed on the ground. The cowpea was included to function as green manure being Cut at flowering with residues left on the soil Surface. Corn and cowpea were sown between cassava rows, in an alternate design, following the first weeding of the main crop (cassava). The cultivar IAC 576-70 showed suitability with respect to organic management, yielding approximatelu 31 Mg ha(-1) of marketable roots. No significant differences were detected between cassava single cropping and any of the intercropping tested systems. Thus, corn crop has considerable potential for additional income to the growers. Yield of 'Eldorado' corn averaged 18.125 ears ha(-1) correspponding to 5,1 Mg ha-1. Residues coming from cowpea cutting brought about an input close to 12 Mg ha(-1), which meant an expressive contribution in nutrient elements, especially nitrogen (about 44 kg N ha(-1)). The legume crop, in addition, completely covered cassava inter-rows demonstrating its potential for controlling erosion and weeds. The triple intercropping becomes advantageous considering that corn harvesting would justify irrigation and that inclusion of cowpea meant benefitial effects to the system and did not interfere on cassava yield.
  • Authors:
    • Raper, R. L.
    • Reddy, K. C.
    • Nyakatawa, E. Z.
    • Reddy, S. S.
    • Reeves, D. W.
    • Lemunyon, J. L.
  • Source: Field Crops Research
  • Volume: 114
  • Issue: 2
  • Year: 2009
  • Summary: Long-term field experiments are needed to fully realize positive and negative impacts of conservation tillage and poultry litter application. A study was initiated on a Decatur silt loam soil at the Tennessee Valley Research and Extension Center, Belle Mina, AL, USA in 1996 to evaluate cotton (Gossypium hirsutum L.) performance with long-term poultry litter (PL) application under different tillages and to Study the build up of phosphorus (P) With application of PL. Treatments include incomplete factorial combinations of three tillage systems [conventional till (CT), mulch till (MT), and no-till (NT)], two cropping systems [cotton-fallow and cotton-winter rye (Secale cereale L.)], and two nitrogen sources and rates [100 kg N ha(-1) from ammonium nitrate (AN), and 100 and 200 kg N ha(-1) from poultry litter (PL)]. Cotton was rotated with corn (Zea mays L.) every third year. Results from 2003 to 2008 showed that all tillages gave similar cotton lint yields with AN at 100 kg N ha(-1). Application of PL at 100 kg N ha(-1) in NT plots resulted in 12 and 11% yield reductions compared to that of CT and MT, respectively. However, NT plots with higher quantity of PL (200 kg N ha(-1)) gave similar yields to CT and MT at 100 kg N ha(-1). During corn years, higher residual fertility of PL, in terms of grain yields, was observed in NT plots compared to CT and MT. Long-term PL application (100 kg N ha(-1) year(-1)) helped to maintain original soil pH in CT and MT while AN application decreased soil pH. In NT plots, PL at 100 kg N ha(-1) was not sufficient to maintain original soil pH, but 200 kg N ha(-1) maintained original pH. Although not-significant, elevated P levels were observed in all tillages compared to original P levels which indicates possibility of P build up in future with further application of PL. Application of PL at double rate (200 kg N ha(-1)) in NT plots resulted in significant build up of P. Results indicate that NT gives similar yields to CT when received AN. but needs higher rate of PL application to achieve similar yields to CT. (C) 2009 Elsevier B,V. All rights reserved.
  • Authors:
    • Sim, R.
    • Maley, S.
    • Fletcher, A.
    • Ruiter, J. M. de
    • George, M.
    • de Ruiter, J. M.
  • Source: Proceedings of the New Zealand Grassland Association
  • Volume: 71
  • Year: 2009
  • Summary: Dairy industry strategies have demanded feeding systems with high productivity and high quality. A 45 t DM/ha annual target for feed production was addressed. Six crop sequence treatments were established in large plots (40*12 m) at Lincoln, Canterbury, in the first year of a 2-year experiment to determine practical upper limits for yield. Summer crops included maize, kale and whole crop barley and these were followed by combinations of winter crops (oats, Italian ryegrass, forage rape, tick beans and triticale). Crops were grown with minimal transition time to reduce potential yield losses, and with optimum nitrogen and irrigation management. Highest plot yield in the first annual crop cycle was 11.9 t DM/ha short of the 45 t DM/ha target. Best productivity was with a maize - triticale+tick bean (32.5 t DM/ha) sequence followed by maize - wheat (30.0 t DM/ha), barley - oats+Italian ryegrass (28.1 t DM/ha) and kale - triticale+tick bean (26.1 t DM/ha). Fertiliser management, crop water use in high input cropping systems are discussed together with practical issues around handling crops with large accumulated biomass.
  • Authors:
    • Salado-Navarro, L. R.
    • Sinclair, T. R.
  • Source: Agricultural Systems
  • Volume: 102
  • Issue: 1/3
  • Year: 2009
  • Summary: Cropping schemes have developed in east-central Argentina for rainfed soybean (Glycine max Merr.) production that invariably employ no-tillage management. Often these schemes include growing soybean in a sequence of crops including wheat ( Triticum aestivum L.) and maize ( Zea mays L.). The full impact of various rotation schemes on soil water balance through a sequence of seasons has not been explored, although the value of these rotations has been studied experimentally. The objective of this work was to investigate through simulations, potential differences in temporal soil water status among rotations over five years. In this study, mechanistic models of soybean (Soy), maize (Maz), and wheat (Wht) were linked over a five-years period at Marcos Juarez, Argentina to simulate soil water status, crop growth, and yield of four no-till rotations (Soy/Soy, Soy/Wht, Soy/Maz, and Soy/Maz/Wht). Published data on sowing dates and initial soil water contents in the first year from a no-till rotation experiment were used as inputs to the model. After the first year, soil water status output from the model was used to initiate the next crop simulation in the sequence. The results of these simulations indicated a positive impact on soil water balance resulting from crop residue on the soil surface under no-till management. Continuous soybean and the two-year soybean/maize rotation did not efficiently use the available water from rainfall. Residue from maize was simulated to be especially effective in suppressing soil evaporation. Thus, the Soy/Maz simulation results indicated that this rotation resulted in enhanced soil water retention, increased deep water percolation, and increased soybean yields compared with continuous soybean crops. The simulated results matched well with experimental observations. The three-crop rotation of Soy/Maz/Wht did not increase simulated soybean yields, but the additional water retained as a result of decreased soil evaporation resulting from the maize residue allowed the addition of a wheat crop in this two-year rotation. Simulated soybean yields were poorly correlated with both the amount of soil water at sowing and the rainfall during the cropping period. These results highlight the importance of temporal distribution of rainfall on final yield. These models proved a valuable tool for assessing the consequences of various rotation schemes now being employed in Argentina on temporal soil water status, and ultimately crop yield.
  • Authors:
    • Sandor, M.
    • Domuta, C.
    • Samuel, A. D.
    • Vuscan, A.
  • Source: Research Journal of Agricultural Science
  • Volume: 41
  • Issue: 2
  • Year: 2009
  • Summary: Agricultural practices that reduce soil degradation and improve agricultural sustainability are needed particularly for preluvosoil. No-tillage planting causes minimal soil disturbance and combined with crop rotation may hold potential to meet these goals. Soil enzyme activities can provide information on how soil management affects the soil potential to perform processes, such as decomposition and nutrient cycling. Soil enzyme activities (actual and potential dehydrogenase, catalase, acid and alkaline phosphatase) were determined in the 0-20-, 20-40- and 40-60-cm layers of a preluvosoil submitted to a complex tillage (no-till and conventional tillage) and crop rotation (2- and 6-crop rotations) experiment. Each activity in both non-tilled and conventionally tilled soil under all crops of both rotations decreased with increasing sampling depth. No-till - in comparison with conventional tillage - resulted in significantly higher soil enzymatic activities in the 0-20- and in significantly lower activities in the deeper layers. The soil under maize or wheat was more enzyme-active in the 6- than in the 2-crop rotation. In the 2-crop rotation, higher enzymatic activities were recorded under wheat than under maize. The enzymatic indicators of soil quality were calculated from the values of enzymatic activities determined in the plots of the 6-crop rotation. The results obtained show that the different hierarchies of the six plots as registered in 2008 may be related to the different nature of crops and kind of fertilisers. This means that by determination of enzymatic activities, valuable information can be obtained regarding fertility status of soils.
  • Authors:
    • Rufty, T.
    • Smyth, T. J.
    • Novais, R. F.
    • Correa, T. F. C.
    • Silva, I. R.
    • Silva, E. F.
    • Gebrim, F. O.
    • Nunes, F. N.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 33
  • Issue: 1
  • Year: 2009
  • Summary: The protective effect of cations, especially Ca and Mg, against aluminium (Al) rhizotoxicity was extensively investigated in the last decades. The mechanisms by which the process occurs are however only beginning to be elucidated. Six experiments were carried out to characterize the protective effect of Mg application in relation to timing, location and crop specificity: Experiment 1 - Protective effect of Mg compared to Ca; Experiment 2 - Protective effect of Mg on distinct root classes of 15 soyabean genotypes; Experiment 3 - Effect of timing of Mg supply on the response of soyabean cultivars to Al; Experiment 4 - Investigating whether the Mg protective effect is apoplastic or simplastic using a split-root system; Experiment 5 - Protective effect of Mg supplied in solution or foliar spraying; and Experiment 6 - Protective effect of Mg on Al rhizotoxicity in other crops. It was found that the addition of 50 mmol litre -1 Mg to solutions containing toxic Al increased Al tolerance in 15 soyabean cultivars. This caused soyabean cultivars known as Al-sensitive to behave as if they were tolerant. The protective action of Mg seems to require constant Mg supply in the external medium. Supplying Mg up to 6 h after root exposition to Al was sufficient to maintain normal soyabean root growth, but root growth was not recovered by Mg addition 12 h after Al treatments. Magnesium application to half of the root system not exposed to Al was not sufficient to prevent Al toxicity on the other half exposed to Al without Mg in rooting medium, indicating the existence of an external protection mechanism of Mg. Foliar spraying with Mg also failed to decrease Al toxicity, indicating a possible apoplastic role of Mg. The protective effect of Mg appeared to be soyabean-specific since Mg supply did not substantially improve root elongation in sorghum, wheat, maize, cotton, rice, or snap bean when grown in the presence of toxic Al concentrations.
  • Authors:
    • Venkateswarlu, B.
    • Vittal, K. P. R.
    • Srinivasarao, C.
    • Kundu, S.
    • Wani, S. P.
    • Sahrawat, K. L.
    • Marimuthu, S.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 40
  • Issue: 15/16
  • Year: 2009
  • Summary: Soil carbon (C) pool plays a crucial role in the soil's quality, availability of plant nutrients, environmental functions, and global C cycle. Drylands generally have poor fertility and little organic matter and hence are candidates for C sequestration. Carbon storage in the soil profile not only improves fertility but also abates global warming. Several soils, production, and management factors influence C sequestration, and it is important to identify production and management factors that enhance C sequestrations in dryland soils. The objective of the present study was to examine C stocks at 21 sites under ongoing rainfed production systems and management regimes over the last 25 years on dominant soil types, covering a range of climatic conditions in India. Organic C stocks in the soil profiles across the country showed wide variations and followed the order Vertisols > Inceptisols > Alfisols > Aridisols. Inorganic C and total C stocks were larger in Vertisols than in other soil types. Soil organic C stocks decreased with depth in the profile, whereas inorganic C stocks increased with depth. Among the production systems, soybean-, maize-, and groundnut-based systems showed greater organic C stocks than other production systems. However, the greatest contribution of organic C to total C stock was under upland rice system. Organic C stocks in the surface layer of the soils increased with rainfall (r=0.59*), whereas inorganic C stocks in soils were found in the regions with less than 550 mm annual rainfall. Cation exchange capacity had better correlation with organic C stocks than clay content in soils. Results suggest that Indian dryland soils are low in organic C but have potential to sequester. Further potential of tropical soils to sequester more C in soil could be harnessed by identifying appropriate production systems and management practices for sustainable development and improved livelihoods in the tropics.
  • Authors:
    • Suyker, A. E.
    • Verma, S. B.
  • Source: Agricultural and Forest Meteorology
  • Volume: 149
  • Issue: 3/4
  • Year: 2009
  • Summary: We have been making year-round measurements of mass and energy exchange in three cropping systems: (a) irrigated continuous maize, (b) irrigated maize-soybean rotation, and (c) rainfed maize-soybean rotation in eastern Nebraska since 2001. In this paper, we present results on evapotranspiration (ET) of these crops for the first 5 years of our study. Growing season ET in the irrigated and rainfed maize averaged 548 and 482 mm, respectively. In irrigated and rainfed soybean, the average growing season ET was 452 and 431 mm, respectively. On average, the maize ET was higher than the soybean ET by 18% for irrigated crops and by 11% for rainfed crops. The mid-season crop coefficient Kc (=ET/ET 0 and ET 0 is the reference ET) for irrigated maize was 1.030.07. For rainfed maize, significant dry-down conditions prevailed and mid-season Kc was 0.840.20. For irrigated soybean, the mid-season Kc was 0.980.02. The mid-season dry down in rainfed soybean years was not severe and the Kc (0.900.13) was only slightly lower than the values for the irrigated fields. Non-growing season evaporation ranged from 100 to 172 mm and contributed about 16-28% of the annual ET in irrigated/rainfed maize and 24-26% in irrigated/rainfed soybean. The amount of surface mulch biomass explained 71% of the variability in non-growing season evaporation totals. Water use efficiency (or biomass transpiration efficiency), defined as the ratio of total plant biomass ( YDM) to growing season transpiration ( T) was 5.200.34 and 5.220.36 g kg -1, respectively for irrigated and rainfed maize crops. Similarly, the biomass transpiration efficiency for irrigated and rainfed soybean crops was 3.210.35 and 2.960.30 g kg -1. Thus, the respective biomass transpiration efficiency of these crops was nearly constant regardless of rainfall and irrigation.
  • Authors:
    • Tarkalson, D. D.
    • Shapiro, C. A.
    • Hergert, G. W.
    • Ferguson, R. B.
    • Dobermann, A. R.
    • Wortmann, C. S.
    • Walters, D. T.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 3
  • Year: 2009
  • Summary: Nutrient management recommendations may change as yield levels and efficiency of crop production increase. Recommendations for P, K, and S were evaluated using results from 34 irrigated corn ( Zea mays L.) trials conducted in diverse situations across Nebraska. The mean yield was 14.7 Mg ha -1 with adequate fertilizer applied. The median harvest index values were 0.52, 0.89, 0.15, and 0.56 for biomass, P, K, and S, respectively. Median grain yields were 372, 49, and 613 kg kg -1 of aboveground plant uptake of P, K, and S, respectively. The estimated critical Bray-1 P level for corn response to 20 kg P ha -1 was 20 mg kg -1 when the previous crop was corn compared with 10 mg kg -1 when corn followed soybean [ Glycine max (L.) Merr.]. Soil test K was generally high with only three site-years
  • Authors:
    • He, J.
    • Wang, X. Y.
    • Gao, H. W.
    • Li, H. W.
    • Yao, Z. L.
  • Source: Soil Research
  • Volume: 47
  • Issue: 8
  • Year: 2009
  • Summary: The furrow opening configuration used by no-till seeders can have a major effect on crop emergence in conservation tillage systems. This is particularly important in annual double-cropping regions (winter wheat and summer maize) of northern China where large volumes of residue remain on the soil surface after maize harvesting. This problem has been investigated using 3 different opening configurations for no-till wheat seeding near Beijing in 2004-05 and 2005-06, and assessing performance in terms of soil disturbance, residue cover index, soil cone index, fuel consumption, winter wheat emergence, plant growth, and subsequent yield. In this cropping system, the single-disc opening configuration significantly decreased mean soil disturbance and increased residue cover index compared with the combined strip-chop and strip-till opening configurations, but winter wheat emergence was 6-9% less, probably due to greater levels of residue cover and greater seed zone soil cone index. Winter wheat growth after seeding in combined strip-chop and strip-till seeded plots was faster than that in single-disc seeded plots and mean yield was greater. The most suitable furrow opening configuration in heavy residue cover conditions appeared to be the strip-chop one, which can provide similar crop performance with marginally better fuel economy than the strip-till opening configuration. These results should be seen as preliminary, but they are still valuable for the design and selection of no-till wheat seeders for double cropping in this region of China.