Soil acidification under subterranean clover (Trifolium subterraneum L.) pastures in north-eastern Victoria

1990 ◽  
Vol 30 (2) ◽  
pp. 195 ◽  
Author(s):  
AM Ridley ◽  
KR Helyar ◽  
WJ Slattery

Eleven paired soil samples to 60 cm depth were collected from grazing properties in north-eastern Victoria. Soils were naturally acid and most were red or yellow podsolics. At each site unfertilised soils (unimproved) and soils which had received regular superphosphate applications (improved) were sampled from either side of a fenceline. The percentage of organic carbon was higher on improved sites but pH was usually lower. Using pH and pH buffering capacity data, the rate of soil acidification under improved pasture, relative to unimproved pasture, was estimated. The improved pastures, on average, required 39 kg CaCO3ka.year to balance the net acid accumulated. The estimated rates of acidification are much lower than those reported previously for similar environments and soil types in New South Wales. There was a relationship between initial profile pH and net acid addition, lower measured net acid addition being associated with low initial soil pH. This paper demonstrates the need for both standardisation of soil pH buffer capacity measurements, and more direct assessment of the role of soil mineral dissolution processes in buffering the pH of strongly acid soils. Until such data exists it will be very difficult to provide convincing information to primary producers regarding the long term alkali input requirements needed for sustainable farming systems.

2003 ◽  
Vol 43 (1) ◽  
pp. 61 ◽  
Author(s):  
G. D. Li ◽  
K. R. Helyar ◽  
C. M. Evans ◽  
M. C. Wilson ◽  
L. J. C. Castleman ◽  
...  

Two permanent pastures (annual pasture v. perennial pasture) were established in 1992 as part of the long-term field experiment, MASTER — Managing Acid Soils Through Efficient Rotations. The primary objective of the experiment was to develop an agricultural system that is economically viable and environmentally sustainable on the highly acidic soils in south-eastern Australia. This paper reports on the effects of lime on the botanical composition changes of annual and perennial pastures over 9 years. In general, lime increased the proportion of the desirable species, such as phalaris (Phalaris aquatica) in perennial pasture and subterranean clover (Trifolium subterraneum) in annual pastures, and decreased the proportion of the undesirable species, such as Vulpia spp., in both annual and perennial pastures, ultimately improving the quality of feed-on-offer to animals. As a result, the limed pastures carried 24% more sheep than the unlimed pastures, while maintaining individual animal performance similar for both limed and unlimed pastures. The phalaris-based perennial pasture was more stable in terms of maintaining the sown species than the annual pasture. Lime improved the persistence of phalaris and the longevity of the phalaris-based pasture should be at least 10 years. Lime changed the direction of plant succession of annual pastures. Without lime, Vulpia spp. gradually became more dominant while ryegrass and subterranean clover became less dominant in annual pastures. With lime, barley grass (Hordeum leporinum) gradually invaded the sward at the expense of ryegrass, thus reducing the benefits of lime, but this effect was less for the perennial pastures than for annual pastures. Liming perennial pastures should be more beneficial than liming annual pastures because of the beneficial effects on pasture composition. In addition, previously published work reported that liming perennial pastures improved sustainability through better use of water and nitrogen.


1991 ◽  
Vol 42 (3) ◽  
pp. 391 ◽  
Author(s):  
DR Coventry ◽  
WJ Slattery

Soil pH decline and net acidification inputs were determined for a long-term crop rotation experiment at Rutherglen in north-eastern Victoria. The rotations utilized were continuous wheat (WW), a 1 : 1 wheat-lupin sequence (WL) and continuous lupins (LL), and each rotation was cropped from 1975-1989. The soil at the site had an initial pH (0.01 mol/LCaCl2) of 6.0 (0-10 cm depth), sandy loam texture, and had a past use of grape vines and then lucerne pasture. The soil pH (0-10 cm) declined for each rotation with time (1977/78-1988/89), decreasing by about 0.8 units for WW and further decreasing with the inclusion of lupin in the rotation. Compared with the WW soil, the WL soil pH was 0.7 and 0.4 units lower at 5-10 cm and 10-15 cm depth and the LL soil pH was 1.0 and 0.8 units lower at 5-10 and 10-15 cm depth. There was no difference in pH between WW and WL below 20 cm depth, but the LL soil had a significantly lower pH to 40 cm depth. Acidification rates were calculated for the period of cropping and for the 3 rotations, with rates of 3.22, 4.11 and 5.26 kmols H+/ha.yr as net acid input for WW, WL and LL rotations. These values represent a rapid rate of soil acidification. The removal of alkalinity in grain accounted for between 15-21% of the overall calculated acidification rate for the 3 rotations. Therefore, it is likely in this cropping system that the acidification largely results from progressive nitrate leaching.


Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 149 ◽  
Author(s):  
TJV Hodge ◽  
DC Lewis

Areas of low soil pH in the south-east of South Australia were delineated by using previously submitted soil samples and soil association maps. A survey was then undertaken in the major soil associations to determine the severity and characteristics of highly acid soils. The acid soil types identified were a siliceous sand over clay (Db/Dy) and a siliceous sand over organic matter/sesquioxide pan (Uc). The top 2.5 cm of both soil types was significantly less acid than the remaining portion of the A horizon, with pH decreasing rapidly with depth until the B horizon, where a substantial soil pH increase occurred. As soil pH (0.01 M CaCl2) decreased below 4.5, extractable soil aluminium (0.01 M CaCl2) increased rapidly, to a maximum extractable concentration of 17 �g g-l. These soil types were also found to be deficient in both phosphorus and potassium, with 65% of the sites having extractable phosphorus concentrations below the critical value of 20 �g g-1 and 35% below the critical value for extractable potassium of 80 �g g-l. For subterranean clover, significant positive correlations were observed between soil pH and plant calcium and sulfur, and between extractable soil aluminium and plant aluminium. Significant negative correlations were observed between soil pH and plant manganese and between extractable soil aluminium and plant calcium and magnesium. For ryegrass, significant positive correlations were observed between extractable soil aluminium and plant aluminium and manganese. Significant negative correlations were observed between soil pH and plant manganese and between extractable soil aluminium and plant calcium. No other significant correlations were obtained. The results are discussed in relation to further acidification and management of these acid siliceous sands.


2011 ◽  
Vol 62 (3) ◽  
pp. 236 ◽  
Author(s):  
S. A. Conning ◽  
M. Renton ◽  
M. H. Ryan ◽  
P. G. H. Nichols

Biserrula (Biserrula pelecinus L.) is a recently domesticated annual pasture legume developed for ley farming systems that have traditionally relied upon subterranean clover (Trifolium subterraneum L.). This study examined competitive interactions between biserrula and subterranean clover and the common broad-leaf weed capeweed (Arctotheca calendula L.) during seedling establishment and vegetative growth, in order to develop guidelines for successful legume pasture management. Two glasshouse experiments were conducted to investigate the allocation of biomass to roots and shoots in biserrula, capeweed, and subterranean clover and its relationship with competitive ability in the first 100 days after sowing. In Experiment 1, capeweed had a higher relative growth rate of shoots and roots than the two legumes and developed a more extensive root system. Experiment 2 consisted of growing binary mixtures of the three species at different densities. The effect of competition on the biomass of biserrula, capeweed, and subterranean clover was best modelled by a power–exponential model. Increasing capeweed densities suppressed the biomass production of both biserrula and subterranean clover, whereas capeweed biomass increased with increasing densities of subterranean clover. This study suggests that the competitive advantage of capeweed is mainly conferred during the seedling stage. It also suggests that biserrula and subterranean clover germinating at the same time can co-exist as a mixed sward, at least up until flowering, if biserrula density is high relative to subterranean clover.


1989 ◽  
Vol 29 (2) ◽  
pp. 209 ◽  
Author(s):  
DR Coventry ◽  
BR Walker ◽  
GR Morrison ◽  
MT Hyland ◽  
JC Avery ◽  
...  

Liming experiments were conducted at 13 sites (soil pH range 4.99-6.27, 0-10 cm depth) in the dryland cropping region of north-eastern Victoria with wheat grown at all sites and barley at 3 sites. Lime increased wheat yields at 9 of the 13 sites with the acid sensitive cultivar Oxley, but the yield increase was not correlated (r2=0.07) with exchangeable Al. Exchangeable A1 was closely related to pH (in 0.01 mmol/L CaCl2). The acid-tolerant wheat cultivars (Matong and Millewa) out-yielded Oxley at a soil pH (CaCl2) of 4.7 and the acid-tolerant cultivars were less responsive to liming. The barley responded to the lime treatment at each of the 3 sites. The use of acid tolerant crop species is recommended on these soils, but an improvement in the predictability of a lime response is required before liming is widely recommended.


1952 ◽  
Vol 3 (2) ◽  
pp. 95 ◽  
Author(s):  
AJ Anderson ◽  
DV Moye

In a study of the factors concerned in the effect of lime on subterranean clover (Trifolium subterraneum L.) on an acid soil where nodulation is defective, it has been found that responses equal to those obtained with heavy dressings of lime can be obtained by the application of molybdenum together with only 2 cwt. of lime per acre at seeding. Marked response to molybdenum was obtained only where low levels of lime were used. Where heavier dressings of lime were applied the clover grew normally and did not then require treatment with molybdenum. Where no lime was used nodulation was defective and, during the first two )ears, response to molybdenum did not occur or was very small. Nodulation subsequently improved on the unlimed soil and response to molybdenum progressively increased over the five-year period of the experiments. In the year of sowing best results were obtained where the inoculated seed was drilled with the lime. The evidence suggests that defective nodulation of subterranean clover may be expected on new land where the soil reactions are less than pH 5.0, and that soils of higher pH but with minimum values less than pH 5.5 are also suspect. The importance of treatment with adequate superphosphate in addition to lime and molybdenum in the development of subterranean clover on this acid soil is stressed. The interpretation and significance of the positive and negative lime-molybdenum interactions obtained are discussed.


1995 ◽  
Vol 35 (2) ◽  
pp. 189 ◽  
Author(s):  
JA Fortune ◽  
PS Cocks ◽  
CK Macfarlane ◽  
FP Smith

The size and composition of pasture legume seedbanks were estimated from 2 surveys on a 460-km west-east transect of the wheatbelt of Western Australia. Survey 1 (in spring) sampled naturalised legumes, and survey 2 (in summer) measured the amount and botanical composition of legume seed from selected sites. Seedbanks were examined in greater detail on 2 farms in the higher rainfall part of the wheatbelt. Survey 2 revealed that mean seedbank size of the poorest 40% of sites (those with 5200 kg seed/ha) was 61 kg/ha, and that 72% of seeds were naturalised clovers. In contrast, the best 60% of sites (those with >200 kg seed/ha) averaged 533 kg seed/ha, of which only 35% was naturalised clover seed, the remainder in both surveys being mainly subterranean clover (Trifolium subterraneum). Mean seed bank size (kg/ha) varied from 359 (survey 2) to 587 (survey 1) and, in both surveys, was poorly correlated with long-term mean annual rainfall and a number of soil parameters. On the 2 farms, seedbank size ranged from 300 to 345 kg/ha (in spring) and from 650 to 740 kg/ha (in summer). Trifolium glomeratum (cluster clover) and subterranean clover were the most widespread species in both surveys. They were present at 35 and 30 of the 57 survey sites, respectively, and at both farms. Most of the subterranean clover collected was cv. Geraldton (22 of 30 sites), the next most frequent cultivar was Dwalganup (6 sites). The currently recommended cultivar, Dalkeith, was found at only 5 sites. Several other legumes including T. tomentosum (16 sites), T. suffocatum (8 sites), Medicago truncatula (7 sites), T. hirtum (4 sites), and M. minima (4 sites) were common, while M. littoralis, M. polymorpha, T. dubium, T. cernuum, T. cherleri, and T. carnpestre were found at single sites. With few exceptions, these are naturalised species and were characterised by flowering times about 20 days later than sown legume cultivars, and seed sizes < 1 mg. The value of these widespread annual legumes to agricultural productivity and sustainability needs to be quantified and their adaptation to wheatbelt farming systems assessed.


Soil Research ◽  
2000 ◽  
Vol 38 (4) ◽  
pp. 837 ◽  
Author(s):  
Z. Rengel ◽  
C. Tang ◽  
C. Raphael ◽  
J. W. Bowden

Nitrification and nitrate leaching have been suggested to be major causes of soil acidification. However, it is unknown whether these processes cause subsoil acidification. Soil column experiments examined the effect of the addition of Ca(NO3)2 or (NH4)2SO4 to the topsoil horizon on subsoil acidification under nodulated lupins (Lupinus angustifolius L.) and subterranean clover (Trifolium subterraneum L.). Nitrate leaching was achieved by adding excess water to the surface of the columns. Where basal nutrients were applied only to the top 10-cm layer, about 60–70% of the total root length of lupin and over 50% of subterranean clover were distributed in that layer. Plants grown without added nitrate for 105 days decreased soil pH at all layers but more significantly in the top 20 cm (by up to 0.7 units); the decrease in pH correlated well with increased root length density of both species (r 2 = 0 .9 8 , n = 9). The addition of Ca(NO3)2 to the top 10-cm layer caused less acidification by about 0.1 pH units at all depths than the treatment without Ca(NO3)2 . Where basal nutrients were applied uniformly throughout the column, root length density of lupin and subterranean clover tended to increase with depth. The addition of (NH4)2SO4 in the top 10 cm significantly increased NO3– concentration in all layers but NH4+ was mainly retained in the top 30-cm layer. Lupin and subterranean clover grown without added NH4+ for 82 days decreased soil pH by 0.3 units at all depths. Compared with the plants receiving no (NH4)2SO 4 , lupin grown with (NH4)2SO4 at 0–10 cm depth in the column caused more acidification by 0.05–0.2 pH units in the top 10 cm but less acidification by 0.15–0.17 units at 10–40 cm depth in the column; subterranean clover grown with (NH4)2SO4 caused more acidification by 0.35–0.46 units in the top 10 cm and less acidification by 0.14–0.19 units in the 20–50 cm layer. The results suggest that the leaching of nitrate from topsoil is unlikely to cause subsoil acidification. In contrast, the uptake of nitrate by the roots reduces net acid production in subsoil layers.


1965 ◽  
Vol 16 (5) ◽  
pp. 733 ◽  
Author(s):  
DN Munns

Lucerne grew poorly without lime on several acid soils on which subterranean clover grew normally. On the moderately acid soils, of pH 5.5–6.0, most of the lime response by lucerne could be attributed to improvement in nodulation and could be eliminated by supplying ammonium nitrate. Strains of medic Rhizobium differed in ability to nodulate lucerne plants in acid soils sufficiently to suggest practical advantage in selecting strains for superiority in this respect. On the more acid soils, of pH 5.0–5.5, lucerne responded to lime or potassium carbonate even when not nitrogen-deficient. This lime response was eliminated by large applications of phosphate. The interaction between lime and phosphate could indicate aluminium toxicity.


Soil Research ◽  
2006 ◽  
Vol 44 (8) ◽  
pp. 739 ◽  
Author(s):  
A. Islam ◽  
R. E. White ◽  
D. Chen

A short-term nitrification assay (SNA) was used to measure the activity of soil nitrifiers and their response to pH change in acid pasture soils (pH 4.8–5.3 in water) at the sites of Maindample and Ruffy in north-eastern Victoria, Australia. Changes in soil pH associated with lime applications in the field resulted in a change in the optimum pH (pHopt) of the nitrifying organisms in the range 4.93–6.94. Nitrification in these soils was predominantly autotrophic, and rates increased from 0.18 to 0.93 μg NO3–-N/g.h with increasing pH. The strong positive correlation between field soil pH and the respective pHopt values suggested that the indigenous nitrifier population had adapted to the change in soil pH. SNA measurements within 6 months of lime application to Maindample soil showed that the soil nitrifying organisms had rapidly adapted to the pH change. However, the residual effect of lime on nitrifier activity was long-lasting (up to 8 years) and may involve more than a simple effect on soil pH. Repeat application of lime further enhanced nitrification activity on an already elevated activity, but only if sufficient time was allowed (>3 years) after the earlier application. Phosphate applications to these soils did not affect the general pH response in nitrifier activity. Both soils had considerable capacity for nitrification, even at pHs much lower than the commonly accepted range for autotrophic nitrifiers.


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