Initial responses of maize and beans to decreased concentrations of monomeric inorganic aluminium with application of manure or tree prunings to an Oxisol in Burundi

Wong, M. T. F.; Akyeampong, E.; Nortcliff, Stephen; Rao, M. R.; Swift, R. S.

doi:10.1007/bf00010282

Cited by 39 publications

(15 citation statements)

References 20 publications

(27 reference statements)

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“…Given that 63% of pasture, 87% of wheat, 89% of dairy soil samples appear to contain Colwell P concentrations above the CV for 90-95% of maximum production, yields are more likely to be constrained by other factors such as lack of water, soil acidity, and other nutrient deficiencies (Table 3). Practices to ameliorate many of these other constraints already exist, including (i) the application of liming materials to manage soil acidity (Snars et al 2004;Wong et al 1998;Wong et al 1995), (ii) improving water holding and P retention, and reducing Colwell P/PBI of sandy soils (Wong and Asseng 2006;Vlahos et al 1989;Summers et al 1993), (iii) relieving subsoil constraints to root growth to capture some leached P (Wong and Asseng 2007), and (iv) using techniques to identify site specific nutrient needs (Wong et al 2001(Wong et al , 2008(Wong et al , 2010.…”

Section: Discussionmentioning

confidence: 99%

Scope to improve phosphorus (P) management and balance efficiency of crop and pasture soils with contrasting P status and buffering indices

Weaver

Wong

2011

Plant Soil

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Aims Fluctuating phosphorus (P) fertiliser costs, water quality issues and on-going debate over global P supply and demand support the need to evaluate and ensure that P is used efficiently in agriculture. Methods We analysed the P balance of farming systems across southern Australia to south east Queensland in relation to P management and soil properties at farm and sub-farm scales. Phosphorus input, yield of products and soil data were collected from Mediterranean, temperate and sub-tropical farming environments to assess soil chemistry and P Balance Efficiency (PBE; percentage of P inputs harvested as P outputs) of sheep, beef, dairy and cropping systems. ResultsThe median PBE was 11% for sheep, 19% for beef, 29% for dairy and 48% for cropping. Phosphorus applied in excess of product removal (P balance) ranged from 18.1 for dairy to 6.1 kg P ha −1 yr −1 for cropping. The bicarbonate-extractable (Colwell) P concentration of surface soils increased with fertiliser application and this differed in relation to P Buffering Index (PBI), production history and the rate of P input. Soil test values for 63% to 89% of soil samples from pastures and crops exceeded critical values (CV; defined by PBI, bicarbonate-extractable P and land use) when little yield improvement would be achieved by applying additional P. A greater percentage of these soil test values exceeded environmental thresholds for water contamination. Conclusions A transition to using lower rates of P fertiliser to maintain soil P fertility at near optimal levels (P maintenance) has not occurred in farming systems represented by these soil samples. Over 50% of the samples had indications of more important constraints (soil acidity, potassium and sulphur deficiency) to yield. Alleviating these constraints is likely to improve PBE. For soils that exceed the CV for P, there is a need to adopt P maintenance practices to improve financial and environmental outcomes.

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Section: Discussionmentioning

confidence: 99%

Scope to improve phosphorus (P) management and balance efficiency of crop and pasture soils with contrasting P status and buffering indices

Weaver

Wong

2011

Plant Soil

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“…Extractable Al levels were reduced to well below the toxic level for rice (Willett and Intrawech, 1988). The decreased levels of exchangeable Al might be associated with the formation of non-toxic organic-Al complexes when straw was added (Bessho and Bell, 1992;Wong et al, 1995) in addition to the higher soil pH maintained with straw addition.…”

Section: Intermittently Flooded Conditionsmentioning

confidence: 93%

Amelioration of growth reduction of lowland rice caused by a temporary loss of soil-water saturation

2004

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Decreases in nutrient availability after loss of soil-water saturation are significant constraints to productivity in lowland rainfed rice soils. The effectiveness of soil amendments like lime and straw in ameliorating these constraints are poorly understood. This pot experiment was conducted in Cambodia to investigate changes in soil chemical properties and nutrient uptake by rice after applying lime or straw to continuously flooded or intermittently flooded soil. In continuously flooded soils, exchangeable Al decreased to below 0.2 cmolc/kg. Liming (pH 6.5-6.8) the continuously flooded soil decreased the levels of acetate extractable Fe and P, plant P uptake and shoot dry matter, but had no effect on either Bray-1 or Olsen extractable P values. By contrast, the addition of straw (3.5 g dry straw/kg soil) increased Bray-1, Olsen, and acetate extractable P, plant P uptake, shoot P, and shoot dry matter. The non-amended soils became strongly acidic after loss of soil water saturation: extractable Al increased to 1.0 cmol c /kg, a potentially harmful level for rice. By contrast, extractable P decreased markedly under loss of soil water saturation as did plant P uptake, shoot P, and shoot dry matter. With loss of soil water saturation, liming substantially depressed the levels of Al but it did not increase plant P uptake, shoot P, and shoot dry matter. Straw addition not only decreased extractable Al levels to well below 0.6 cmol c /kg under loss of soil water saturation, but it also increased extractability of soil P, plant P uptake, shoot P, and shoot dry matter. Thus, in rainfed environments, the incorporation of straw may be more effective than liming to pH 6.8 for minimising the negative effects of temporary loss of soil-water saturation on P availability, P uptake, and growth of rice.

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“…Reduced Al toxicity to maize, in addition to increased supply of nitrogen, could be responsible for the favorable response of HI in these situations. Many studies have indicated the reduction of Al toxicity with the addition of such a large amount of organic residues because their decomposition products would bind Al and reduce Al saturation (Wong et al, 1995).…”

Section: Effect On Crop Yieldsmentioning

confidence: 99%

Biophysical interactions in tropical agroforestry systems

Rao¹,

Nair²,

Ong³

1998

Forestry Sciences

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111

124

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Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interactions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems.In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offset the large competitive effect of hedgerows with crops for water and/or nutrients. Whereas improved soil fertility and microclimate positively influence crop yields underneath the canopies of scattered trees in semiarid climates, intense shading caused by large, evergreen trees negatively affects the yields. Trees in boundary plantings compete with crops for above-and belowground resources, with belowground competition of trees often extending beyond their crown areas. The major biophysical interactions in improved planted fallows are improvement of soil nitrogen status and reduction of weeds in the fallow phase, and increased crop yields in the subsequent cropping phase. In such systems, the negative effects of competition and microclimate modification are avoided in the absence of direct tree-crop interactions.Future research on biophysical interactions should concentrate on (1) exploiting the diversity that exists within and between species of trees, (2) determining interactions between systems at different spatial (farm and landscape) and temporal scales, (3) improving understanding of belowground interactions, (4) assessing the environmental implications of agroforestry, particularly in the humid tropics, and (5) devising management schedules for agroforestry components in order to maximize benefits.

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Initial responses of maize and beans to decreased concentrations of monomeric inorganic aluminium with application of manure or tree prunings to an Oxisol in Burundi

Cited by 39 publications

References 20 publications

Scope to improve phosphorus (P) management and balance efficiency of crop and pasture soils with contrasting P status and buffering indices

Scope to improve phosphorus (P) management and balance efficiency of crop and pasture soils with contrasting P status and buffering indices

Amelioration of growth reduction of lowland rice caused by a temporary loss of soil-water saturation

Biophysical interactions in tropical agroforestry systems

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