Effect of additions of brown coal and peat on soil solution composition and root growth in acid soil from wheatbelt of western Australia

2000 ◽  
Vol 31 (5-6) ◽  
pp. 743-758 ◽  
Author(s):  
Y. Yazawa ◽  
M.T.F. Wong ◽  
R.J. Gilkes ◽  
T. Yamaguchi
Soil Research ◽  
1995 ◽  
Vol 33 (4) ◽  
pp. 689 ◽  
Author(s):  
PW Moody ◽  
DG Edwards ◽  
LC Bell

A layer of mono- or di-ammonium phosphate (MAP and DAP, respectively) was placed in contact for 5 days with duplicate columns of soil at a water content equivalent to 10 kPa matric suction. This was designed to simulate the effects of banded fertilizer on soil solution composition. Five soils were used: 0-10 cm samples from a Kurosol, a Ferrosol, a Vertosol and a Kandosol, and a 50-60 cm sample from the Kandosol. After the contact period, soil sections were recovered at successive 5 mm intervals from the fertilizer layer, the last section being 45-60 mm from the layer. Soybean (Glycine max (L.) Merr.) seedlings were grown for 48 h in each section and relative root elongation was determined. Soil solution was then extracted from each section and analysed. The amount of inorganic P in the soil solution (P-i) was summed over all soil sections for each soil and each P source and was found to be correlated with distance of P movement from the simulated band (r = 0 . 792, P < 0.01). Of several soil chemical parameters of the control (unfertilized) soils regressed against Pi, the following showed significant (P = 0.05) negative correlations: Ca and Mg concentrations in the soil solution for Pi from both MAP and DAP, exchangeable Ca and Mg for DAP, and citrate-dithionite extractable Fe and Al for MAP. These results suggest that adsorption (and possibly precipitation) reactions with Fe and Al hydrous oxides contributed to the removal of P-i from solution in the presence of MAP. However, with DAP as the fertilizer source, precipitation reactions involving Ca and Mg were the predominant factors. Dissolved organic C in the soil solution increased adjacent to both DAP and MAP, with larger amounts in proximity to DAP being a consequence of the higher soil solution pH (~ 7). Soil solution Si increased in all soils adjacent to both DAP and MAP, with concentrations being higher in the MAP treatments. Dissolution of aluminosilicates in the acidic conditions near MAP (pH ~5) was the probable cause. Relative root elongation (RRE) of soybean was restricted in soil sections close to the fertilizer. When RRE was plotted against each of soil solution EC, NH3 activity, and calcium activity ratio (CAR), a single curvilinear function described the relationship between RRE and CAR for all soils and both P sources. It is concluded that a salt-induced Ca deficiency was the cause of restricted root growth in proximity to DAP and MAP, rather than an osmotic effect or NH3 toxicity.


Soil Research ◽  
1994 ◽  
Vol 32 (4) ◽  
pp. 847 ◽  
Author(s):  
CDA Mclay ◽  
GSP Ritchie ◽  
WM Porter ◽  
A Cruse

Two field trials were sampled to investigate the changes to soil solution chemical properties of a yellow sandplain soil with an acidic subsoil following the application of gypsum and lime to the soil surface in 1989. The soils were sandy textured and located in a region of low annual rainfall (300-350 mm). Soil was sampled annually to a depth of 1 m and changes in soil solution composition were estimated by extraction of the soil with 0.005 M KCl. Gypsum leaching caused calcium (Ca), sulfate (SO4) and the ionic strength to increase substantially in both topsoil and subsoil by the end of the first year. Continued leaching in the second year caused these properties to decrease by approximately one-half in the topsoil. Gypsum appeared to have minimal effect on pH or total Al (Al-T), although the amount of Al present as toxic monomeric Al decreased and the amount present as non-toxic AlSO+4 ion pairs increased. Magnesium (Mg) was displaced from the topsoil by gypsum and leached to a lower depth in the subsoil. In contrast, lime caused pH to increase and Al to decrease substantially in the topsoil, but relatively little change to any soil solution properties was observed in the subsoil. There was an indication that more lime may have leached in the presence of gypsum in the first year after application at one site. Wheat yields were best related to the soil acidity index Al-T/EC (where EC is electrical conductivity of a 1:5 soil:water extract), although the depth at which the relationship was strongest in the subsoil varied between sites. The ratio Al-T/EC was strongly correlated with the activity of monomeric Al species (i.e. the sum of the activities of Al3+, AlOH2+ and Al(OH)+2 in the soil solution. An increase in the concentration of sulfate in the subsoil solution (which increased the ionic strength, thereby decreasing the activity of Al3+, and also increased the amount of Al present as the AlSO+4 ion pair) was probably the most important factor decreasing Al toxicity to wheat. The results indicated that gypsum could be used to increase wheat growth in aluminium toxic subsoils in sandy soils of low rainfall regions and that a simple soil test could be used to predict responses.


2000 ◽  
Vol 51 (6) ◽  
pp. 701 ◽  
Author(s):  
C. L. Davies ◽  
D. W. Turner ◽  
M. Dracup

We studied the adaptation of narrow-leafed lupin (Lupinus angustifolius) and yellow lupin (L. luteus) to waterlogging because yellow lupin may have potential as a new legume crop for coarse-textured, acidic, waterlogging-prone areas in Western Australia. In a controlled environment, plants were waterlogged for 14 days at 28 or 56 days after sowing (DAS). Plants were more sensitive when waterlogged from 56 to 70 DAS than from 28 to 42 DAS, root growth was more sensitive than shoot growth, and leaf expansion was more sensitive than leaf dry weight accumulation. Waterlogging reduced the growth of narrow-leafed lupin (60–81%) more than that of yellow lupin (25–56%) and the response was more pronounced 2 weeks after waterlogging ceased than at the end of waterlogging. Waterlogging arrested net root growth in narrow-leafed lupin but not in yellow lupin, so that after 2 weeks of recovery the root dry weight of yellow lupin was the same as that of the control plants but in narrow-leafed lupin it was 62% less than the corresponding control plants. Both species produced equal amounts of hypocotyl root when waterlogged from 28 to 42 DAS but yellow lupin produced much greater amounts than narrow-leafed lupin when waterlogged from 56 to 70 DAS.


2010 ◽  
Vol 34 (3) ◽  
pp. 444-456 ◽  
Author(s):  
REBECCA E. HALING ◽  
RICHARD J. SIMPSON ◽  
RICHARD A. CULVENOR ◽  
HANS LAMBERS ◽  
ALAN E. RICHARDSON

Soil Research ◽  
1995 ◽  
Vol 33 (3) ◽  
pp. 443 ◽  
Author(s):  
NS Jayawardane ◽  
HD Barrs ◽  
WA Muirhead ◽  
J Blackwell ◽  
E Murray ◽  
...  

Subsoil acidity causes low crop production, which is often associated with shallow root development and restricted soil water extraction. In part I of this series, lime-slotting of an acid soil was shown to improve the soil physical and chemical characteristics for root growth. In a lysimeter study on an acid soil, the effects of several soil ameliorative treatments on root growth, water extraction and yields of a medic crop were evaluated. Large lysimeter cores of 0.75 m diameter and 1.35 m deep were used. The soil treatments included a non-ameliorated acid soil, lime-slotting with a 0.15 m wide and 0.8 m deep slot containing 20 t ha-1 of lime, lime-slotting combined with surface phospho-gypsum application at 10 t ha-1, and complete amelioration of the entire soil volume by mixing lime at 133 t ha-1 and repacking to a low bulk density of 1.1 t m-3. In the non-ameliorated acid soil, medic roots were confined to the surface (0.1 m) layer, resulting in limited water extraction of 32 mm during a prolonged drying cycle, and a low dry matter yield of 70 g m-2. In the lime slotted soil, roots grew within the slot to its full depth, although penetration into the undisturbed soil was restricted to the soil immediately adjacent to the slot. Consequently, the root length per unit surface area (La) at depths below 0.1 m depth was increased to 9.9 km m-2. During a drying cycle, water extraction increased to 58 mm. The increased water extraction came from both the slotted soil and the undisturbed soil between slots. This led to an increase in dry matter yields to 270 g m2. In lime-slotted soils with surface gypsum applications, the root growth and crop water extraction patterns were similar to the lime-slotted soil. Repacking limed soil resulted in similar root lengths (L(a) 10.0 km m-2) as lime-slotted soil. However, owing to more uniform distribution of roots in the repacked soil, water extraction was increased to 100 mm and yields increased to 590 g m-2. Yields of non-ameliorated soil were only 12% of the repacked, limed soil. However, lime-slotting which involves loosening only 25% of the soil surface area and addition of only one-sixth of the amount of lime required for complete soil amelioration, led to marked increases in yield (46% of the yield of repacked soil). Future field studies are required to evaluate the optimum limed-slot configurations required for different soils, crops and climatic regimes.


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