Application of a model of the decomposition of soil organic matter

Smith, O.L.

doi:10.1016/0038-0717(79)90028-2

Cited by 17 publications

(7 citation statements)

References 10 publications

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“…A and a, soil given whole cattle slurry; B and 6, soil not given fertilizer; C and c, soil given sterilized slurry. pattern is roughly in keeping with the model proposed by Smith (1979), in which the net consumption of NHJ caused by the growth of the microbial population during the initial 2 months incubation is followed by the simultaneous increase of nitrification and ammonification with coupling between the two processes. In the present experiments, however, the high NO3 levels predicted by Smith's theory are not attained because of an apparent partial inhibition of nitrification during the third phase mentioned above.…”

Section: Resultssupporting

confidence: 90%

“…Table 3 also shows that, as in most soils, the labile substrate contains a smaller proportion of mineralizable N than the recalcitrant substrate. The delay in the commencement of the mineralization of the second substrate might be explained by the same arguments as have been used by Smith (1979) in presenting a model of microbial population growth featuring a similar lag for the more recalcitrant substrates. Another explanation is suggested by the results of Tusneem & Patrick (1971), who found that the kinetics of nitrogen mineralization changed from a zero-lag exponential to a sigmoid curve as the C/N ratio of the added substrate increased.…”

Section: Resultsmentioning

confidence: 78%

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Effect of cattle slurry fractions on nitrogen mineralization in soil

et al. 1988

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SummaryThe mineralization kinetics of nitrogen in acid soils, and their modification by the addition of an organic fertilizer (cattle slurry), were studied by incubating a humic cambisol for 36 weeks using a method based on that of Keeney & Bremner (1967). The cumulative curve of the quantity of nitrogen mineralized in soil not given fertilizer departs significantly from Stanford's theoretical model, which predicts linear dependence of nitrogen mineralized upon √t. The observed kinetics are interpreted as due to the superposition of two mineralization processes involving different substrates.The cumulative mineralized nitrogen curves for soil samples enriched with the various slurry fractions likewise reflect complex kinetics involving at least two main substrates. Consideration of the net mineralized nitrogen shows that F,, the solid fraction with the highest C/N ratio, clearly induced immobilization of nitrogen during the first 130 days of incubation, and analysis of the NO3/NH4 ratio suggests that this immobilization was probably at the expense of nitrate. F3, the liquid fraction, first induced a brief period of mineralization and then stabilized nitrogen levels, giving rise to a reduction in net mineralized nitrogen. The addition to the soil of F2, the semi-liquid fraction, produced results intermediate between those of the other two fractions.In conclusion, the increase in organic nitrogen in the soil after addition of cattle slurry depends in the short term on the liquid and semi-liquid fractions, whereas long-term effects involve both the stable residues of these fractions and the more solid fraction. The labile fraction of the pool of mineralizable N benefits more than the recalcitrant fraction, and the time constants of the mineralization process are reduced.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 78%

Effect of cattle slurry fractions on nitrogen mineralization in soil

et al. 1988

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“…T h e greatest differences between the plots occurred in December (11.4"C in plot N and 10.3 "C in plot D) and August (25.5 "C in plot N and 29.5 "C in plot D). The maximum temperatures in plot D from July to September were about 3 "C higher than in plot N. It is known that an increase in soil temperature increases the mineralization of stored soil organic matter (Smith, 1979).…”

Section: Resultsmentioning

confidence: 85%

Soil degradation and desertification induced by vegetation removal in a semiarid environment

Albaladejo

Martínez-Mena

Roldán

et al. 1998

Soil Use and Management

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The fragile soils at the transition between semiarid and arid areas are continuously threatened by human activity, which frequently involves the elimination of plant cover. We studied the impact of vegetation removal on soil characteristics in senliarid Mediterranean Spain using two plots (15 m x 5 m), installed on a north facing slope of 23%.Vegetation was removed from one of the plots (disturbed plot), and changes in the soil characteristics were compared with an undisturbed control plot. Fifty-five months after vegetation removal the organic carbon content decreased bj 35%, the percentage of stable aggregates by 31% and soil bulk density increased by 8%.The models that best represented the changes of these parameters with time were linear equations. There were no significant differences between the water retention capacity or saturated hydraulic conductivity of the treatments. The rapid loss of soil organic matter and the consequences in terms of physical soil properties were considered to be the main factors in soil degradation. No symptoms of natural recovery were observed in the disturbed plot and the tendency was for a steady deterioration in soil behaviour. This means that human activity or climatic change leading to less vegetation could result in irreversible soil degradation in semiarid areas.

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“…A major determinant of tissue decomposition rates is the presence of sufficient N to promote vigorous microbial activity. Thatch in turfgrass is likely to possess a high C/N ratio unless attempts are made to apply N so that it is held as long as possible in the thatch layer (Beard, 1973;Hunt, 1978;Smith, 1979). Frequent applications oflow rates of soluble N sources, or less frequent applications of slowly soluble sources are necessary to achieve this purpose.…”

Section: Discussionmentioning

confidence: 99%

Fungicide Effects on Thatch Depth, Thatch Decomposition Rate, and Growth of Kentucky Bluegrass¹

Smiley¹,

Fowler²,

Kane³

et al. 1985

Agronomy Journal

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Development of improved management strategies for controlling thatch on tuifgrasses is limited by an incomplete understanding of thatch biology. Mechanisms whereby fungicides cause thatch to accumulate in turfgrass were investigated, by evaluating the influences of fungicides on rates of tissue production and thatch decomposition. Fourteen fungicides, one nematicide, and five mixed‐fungicide programs were applied repeatedly (up to nine times annually), over a 4‐yr period, to a field‐grown Kentucky bluegrass (Poa pratensisL.) turf on a soil of the fine, illitic mesic family of Glossoboric Hapludalfs. Measurements were made of thatch depths, root and leaf clipping weights, shear strength of sod, and decomposition rates for thatch implanted into the turfs. Compounds that caused thatch to become deeper (p= 0.05) than in the nontreated control included benomyl, cadmium succinate, fenamiphos, iprodione, and mancozeb. Treatments in which these pesticides were used were characterized by sod shear strengths greater (p= 0.05) than in the control. Thatch accumulations were related mostly to the amounts of roots in the surface 4 cm. None of the studied fungicides significantly (p= 0.10) reduced the apparent rate of thatch decomposition. Fungicides in this study therefore appeared to induce thatchiness in Kentucky bluegrass by increasing the rates of root and rhizome production and not by reducing the rate of litter decomposition.

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Application of a model of the decomposition of soil organic matter

Cited by 17 publications

References 10 publications

Effect of cattle slurry fractions on nitrogen mineralization in soil

Effect of cattle slurry fractions on nitrogen mineralization in soil

Soil degradation and desertification induced by vegetation removal in a semiarid environment

Fungicide Effects on Thatch Depth, Thatch Decomposition Rate, and Growth of Kentucky Bluegrass¹

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Application of a model of the decomposition of soil organic matter

Cited by 17 publications

References 10 publications

Effect of cattle slurry fractions on nitrogen mineralization in soil

Effect of cattle slurry fractions on nitrogen mineralization in soil

Soil degradation and desertification induced by vegetation removal in a semiarid environment

Fungicide Effects on Thatch Depth, Thatch Decomposition Rate, and Growth of Kentucky Bluegrass1

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Fungicide Effects on Thatch Depth, Thatch Decomposition Rate, and Growth of Kentucky Bluegrass¹