EFFECTS OF SOIL ACIDITY ON RHIZOBIA NUMBERS, NODULATION AND NITROGEN FIXATION BY ALFALFA AND RED CLOVER

1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.

1977 ◽  
Vol 57 (2) ◽  
pp. 157-164 ◽  
Author(s):  
D. C. PENNEY ◽  
M. NYBORG ◽  
P. B. HOYT ◽  
W. A. RICE ◽  
B. SIEMENS ◽  
...  

The amount of cultivated acid soil in Alberta and northeastern British Columbia was estimated from pH values of farm samples analyzed by the Alberta Soil Testing Laboratory, and the effect of soil acidity on crops was assessed from field experiments on 28 typical acid soils. The field experiments consisted of two cultivars of barley (Hordeum vulgare L.) and one cultivar each of rapeseed (Brassica campestris L.), red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) grown with and without lime for 2 yr. There are about 30,000 ha of soils with a pH of 5.0 or less where soil acidity seriously restricts yields of all four crop species. There are approximately 300,000 ha with a soil pH of 5.1–5.5 where liming will on the average increase yields of alfalfa by 100%, yields of barley by 10–15%, and yields of rapeseed and red clover by 5–10%. There are a further 1,600,000 ha where soil pH ranges from 5.6 to 6.0 and liming will increase yields of alfalfa by approximately 50% and yields of barley, rapeseed and red clover by at least 4–5%.


Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 31 ◽  
Author(s):  
Z Hochman ◽  
GJ Crocker ◽  
EB Dettman

The 'Lime-it' model is a decision support system for graziers wanting to lime acid soils. In this study we used field experimental data to test, improve and validate the model's ability to predict changes in soil pH due to variable rates of lime. Data from 13 field experiments, in which soil parameters were measured 1 year after liming acid soils, were used to derive an index of pH responsiveness to lime (LRI) at each site. Multivariate analysis was used to derive a predictive model: LRI was found to be significantly correlated (P < 0.0001) with hydrogen ion concentration ([H+]x 105 ), exchangeable aluminium (Al), exchangeable cations (TEC) and percent organic carbon (C) data of the unlimed soils. The multivariate equation was then tested against an independent data set by comparing the predicted pH change with the measured pH change for eight soils. This evaluation, though generally acceptable, showed a small but significant deviation from the desired 1:1 ratio between observed and predicted pH change. We re-calibrated the model for the combined data to derive the model: LRI = 0.764 + 0.042 [H+] - 0.016 TEC - 0.097 Al - 0.016 C. When this model was tested over the whole data set for predicted v. measured pH changes, the following result was found: measured pH change = 1.01 (predicted pH change) - 0.05 (R2 = 0.85, n = 308). The implications of the predictive equation are considered with regard to the mechanisms that are thought to be associated with pH buffering.


1970 ◽  
Vol 21 (3) ◽  
pp. 427 ◽  
Author(s):  
AD Robson ◽  
JF Loneragan

On a moderately acid soil (pH 4.6 in 115 suspension of soil in 0.01M calcium chloride), nodulation of Medicago truncatula cv. Cyprus responded markedly to increasing applications of calcium carbonate, which increased soil pH. Since the effect of increasing soil pH on the percentage nodulation could be replaced to a large extent by increasing the inoculation level, it appeared that nodulation was restricted by the inability of Rhizobium meliloti to survive or multiply in the acid soil. The growth of R, meliloti appeared more sensitive to soil acidity than growth of the host plant of annual Medicago species. It is suggested that more acid-tolerant strains of R. meliloti would permit annual Medicago species to be grown successfully on moderately acid soils, thus extending the range of soils suitable for the growth of these species.


Soil Research ◽  
2017 ◽  
Vol 55 (4) ◽  
pp. 341 ◽  
Author(s):  
Craig A. Scanlan ◽  
Ross F. Brennan ◽  
Mario F. D'Antuono ◽  
Gavin A. Sarre

Interactions between soil pH and phosphorus (P) for plant growth have been widely reported; however, most studies have been based on pasture species, and the agronomic importance of this interaction for acid-tolerant wheat in soils with near-sufficient levels of fertility is unclear. We conducted field experiments with wheat at two sites with acid soils where lime treatments that had been applied in the 6 years preceding the experiments caused significant changes to soil pH, extractable aluminium (Al), soil nutrients and exchangeable cations. Soil pH(CaCl2) at 0–10cm was 4.7 without lime and 6.2 with lime at Merredin, and 4.7 without lime and 6.5 with lime at Wongan Hills. A significant lime×P interaction (P<0.05) for grain yield was observed at both sites. At Merredin, this interaction was negative, i.e. the combined effect of soil pH and P was less than their additive effect; the difference between the dose–response curves without lime and with lime was greatest at 0kgPha–1 and the curves converged at 32kgPha–1. At Wongan Hills, the interaction was positive (combined effect greater than the additive effect), and lime application reduced grain yield. The lime×P interactions observed are agronomically important because different fertiliser P levels were required to maximise grain yield. A lime-induced reduction in Al phytotoxicity was the dominant mechanism for this interaction at Merredin. The negative grain yield response to lime at Wongan Hills was attributed to a combination of marginal soil potassium (K) supply and lime-induced reduction in soil K availability.


1965 ◽  
Vol 45 (2) ◽  
pp. 221-234 ◽  
Author(s):  
L. B. MacLeod ◽  
L. P. Jackson

Alfalfa, red clover, ladino clover, alsike clover, and birdsfoot trefoil were germinated in soil (pH 6.5) or in inert silica (8 mesh) and allowed to root in a [Formula: see text] Hoagland and Snyder's nutrient solution (pH 4.5) with 0, 0.5, 1, 2, 4, and 10 p.p.m. of added aluminum. Each species, germinated in silica, was also rooted in an unlimed acid soil (pH 4.6) and the same soil limed to a pH of 6.5.Concentration of aluminum ion remaining in solution was 0, 0.1, 0.2, 0.5, 1.0, and 2.0 p.p.m. Saturation extracts of the unlimed and limed soil contained 0.45 and 0.0 p.p.m respectively of aluminum ion in solution. The pH of the nutrient solutions with 0.5, 1, and 2 p.p.m. of added aluminum increased to 5.0 or higher in 24 hours while that with 4 and 10 p.p.m. of added aluminum remained relatively constant.Seedling weight and chemical composition of the tops and root portions varied significantly between species. Alfalfa and red clover showed the most vigorous rate of establishment, and yields were higher with 0.1 and 0.2 p.p.m. concentration of aluminum ion than with the zero treatment. Significant restriction of top and root growth of all species occurred with less than 1.0 p.p.m. of aluminum ion while 2.0 p.p.m. was toxic to root growth. Growth restrictions were more severe at 21 days after seeding than at the 28- or 32-day stages. Yield of tops and roots growing into unlimed acid soil were 73 and 71% respectively of those growing into limed soil. Aluminum taken up by the plant was concentrated in the roots and only with the concentration of aluminum at 2.0 p.p.m. was the content in the tops increased significantly. Phosphorus in the roots, which increased significantly with aluminum ion concentration, was apparently immobilized by aluminum. Percent Ca in the roots increased and in the tops decreased with increasing concentrations of aluminum. Content of K and Mg also varied with aluminum concentration.


1993 ◽  
Vol 2 (3) ◽  
pp. 197-270
Author(s):  
Markku Yli-Halla

The Zn status of cultivated soils of Finland was investigated by chemical analyses and bioassays. The effect on ryegrass of different Zn fertilizers and Zn rates was studied in pot experiments and their effect on barley and timothy in field experiments. In an uncontaminated surface soil material of 72 mineral soils and 34 organogenic soils, total Zn (Zntot) was 10.3-202 mg kg-1(median 66 mg kg-1). In mineral soils, Zntot correlated positively with clay content (r = 0.81***) and in organogenic soils negatively with organic C (r = -0.53***). Zinc bound by organic matter and sesquioxides was sequentially extracted by 0.1 M K4P2O7 (Znpy) and 0.05 M oxalate at pH 2.9 (Znox), respectively. The sum Znpy + Znox, a measure of secondary Zn potentially available to plants, was 2 - 88% of Zntot and was the lowest in clay (median 5%) and highest in peat soils (median 49%). Water-soluble and exchangeable Zn consisted of0.3 - 37% (median 3%) of Zntot, the percentage being higher in acid soils, particularly in peat soils. Zinc was also extracted by 0.5 M ammonium acetate - 0,5 M acetic acid - 0.02 M Na2-EDTA at pH 4.65 (ZnAC), the method used in soil testing in Finland. The quantities of ZnAC (median 2.9 mg dm-3, range 0.6 - 29.9 mg dm-3) averaged 50% and 75% of Znpy + Znox in mineral and organogenic soils, respectively, and correlated closely with Znpy. In soil profiles, ZnAC was with few exceptions higher in the plough layer (0 - 20 cm) than in the subsoil (30 - 100 cm). In an intensive pot experiment on 107 surface soils, four crops of ryegrass took up 2 - 68% (median 26%)of Znpy + Znox. The plant-available Zn reserves were not exhausted even though in a few peat soils the Zn supply to grass decreased over time. Variation of Zn uptake was quite accurately explained by ZnAC but increasing pH had a negative impact on Zn uptake. Application of Zn (10 mg dm-3 of soil as ZnSO4 * 7 H2O) did not give rise to yield increases. In mineral soils, increase of plant Zn concentration correlated negatively with soil pH while ZnAC was of secondary importance. In those organogenic soils in which the reserves of native Zn were the most effectively utilized, plant Zn concentration also responded most strongly to applied Zn. In two 2-year field experiments, Zn application did not increase timothy or barley yields. Zinc concentration of timothy increased from 30 mg kg-1 to 33 and 36 mg kg-1 when 3 or 6 kg Zn ha-1 was applied, respectively. The efficiency of ZnSO4 * 7 H2O alone did not differ from that of a fertilizer where ZnSO4 * 7H20 was granulated with gypsum. Zinc concentration of barley grains increased by foliar sprays of Na2Zn-EDTA but only a marginal response to soil-applied Zn (4.8 or 5.4 kg ha-1 over three years) was detected in three 3-year experiments. High applications of Zn to soil (15 or 30 kg ha-1 as ZnSO4 * 7H2O) were required to increase Zn concentration of barley markedly. In order to prevent undue accumulation of fertilizer Zn in soil, it is proposed that Zn fertilizer recommendations for field crops should be based on both soil pH and ZnAC. In slightly acid and neutral soils, even if poor in Zn, response of plant Zn concentration to applied Zn remains small while there is a high response in strongly acid soils.


2002 ◽  
Vol 82 (2) ◽  
pp. 227-238 ◽  
Author(s):  
Joann K Whalen ◽  
Chi Chang ◽  
George W Clayton

Crop production on acid soils can be improved greatly by adjusting the pH to near neutrality. Although soil acidity is commonly corrected by liming, there is evidence that animal manure amendments can increase the pH of acid soils. Fresh cattle manure and agricultural lime were compared for their effects on soil acidity and the production of canola (Brassica napus L.) and wheat (Triticum aestivum L.) in a greenhouse study. Canola and wheat yield, the nutrient content of grain and straw, and selected soil properties were determined on a Gray Luvisol (pH 4.8) from the Peace Region of Alberta. Soil pH increased with lime and manure applications, and canola and wheat yields were higher in limed and manure-amended soils than unfertilized, unlimed soils. Macronutrient uptake by canola and wheat was generally improved by liming and manure applications, and micronutrient uptake was related to the effects of lime and manure on soil pH. An economic analysis compared the costs of using cattle manure and lime to increase soil pH to 6.0. The costs of applying lime and fresh cattle manure to increase soil pH were compared, based on the fees for purchasing and applying lime or loading, hauling and applying manure. The nutrient value of manure was calculated based on the quantities of plant-available N, P and K in fresh manure. At distances less than 40 km, it is economical to substitute fresh cattle manure for agricultural lime to increase soil pH of acidic soils. However, good manure management practices should be followed to minimize the risk of nutrient transport and environmental pollution from agricultural land amended with cattle manure. Key words: Agricultural economics, canola production, cattle manure, lime, soil pH, wheat prodution


1994 ◽  
Vol 2 (2) ◽  
pp. 187-214 ◽  
Author(s):  
D. A. Wright ◽  
P. M. Welbourn

Cadmium is a nonessential element that can be toxic and carcinogenic. On a global scale, the ratio anthropogenic to natural emissions of cadmium is approximately 7:1. Sources of cadmium for freshwater and salt water include atmospheric deposition, direct and via runoff, as well as direct discharges into water or watersheds. Thirty percent of the atmospheric emissions fall onto water. In freshwater, the cadmium ion is the predominant dissolved form, while in seawater, chloride dominates. Much of the cadmium added to aquatic systems accumulates in sediments where it presents a risk to benthic biota and under certain conditions may reenter the water column. The cadmium ion is the most bioavailable to aquatic biota; factors affecting availability include salinity, dissolved organic matter, and hydrogen ion concentration, which affect the chemical forms of cadmium. Hydrogen and other ions, most notably calcium, also affect cadmium uptake and toxicity, through competition and physiological effects. The concentrations of cadmium that result in acute or chronic toxicity vary over several orders of magnitude, with certain freshwater fish and invertebrates being the most sensitive. Long-term field experiments and chronic toxicity tests on invertebrates suggest that the present Canadian guideline of 200 ng Cd∙L−1 for the protection of freshwater biota may be too high. Aquatic animals and plants, like most organisms, produce metal binding proteins, called metallothioneins, in response to cadmium. Some species or varieties within a species of aquatic biota are tolerant to cadmium. The relationship between cadmium tolerance and metallothionein is still incompletely resolved.Key words: cadmium, seawater, freshwater, availability, toxicity, metallothionein, tolerance, food chain.


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