Dynamics of microorganisms, microbivores and nitrogen mineralisation in winter wheat fields under conventional and integrated management

doi:10.1016/0167-8809(94)90039-6

Agriculture, Ecosystems & Environment

Volume 51, Issues 1–2, November 1994, Pages 129-143

https://doi.org/10.1016/0167-8809(94)90039-6 Get rights and content

Abstract

To reduce environmental problems, integrated farming has been proposed, which may involve a considerable reduction of fertiliser-N input. A reduced fertiliser-N input must be compensated for by a higher N mineralisation from organic matter. To reduce losses and to facilitate optimal use of the N mineralised for crop growth, knowledge of the effects of management on soil orgaisms and on their role in N cycling is needed. Therefore, biomass and activity of bacteria, biomasses of fungi, bacterivorous amoebae, flagellates and nematodes, and in situ N mineralisation were monitored during a full year in a winter wheat field under conventional management (CONV) and integrated management (INT).

Fungal biomass was about 100-fold lower than bacterial biomass. The average bacterial biomass was not significantly higher in INT than in CONV, whereas amoebae and nematodes were 64% and 22% higher, respectively. Average N mineralisation was 30% higher in INT. The differences are attributed to the approximately 30% higher organic matter content of INT. Bacterial biomass and frequency of dividing-divided cells (FDDC) were relatively low in December and January, probably owing to temperatures just above 0°C. At about 5°C in February and March, relatively high FDDC values and a doubling of bacteria occurred. During summer, FDDC values were relatively low and bacterial numbers were stable, probably owing to nutrient limitation. After harvest and skim ploughing, rapid increases in FDDC and bacteria were found. In the non-fumigated INT field, protozoan peaks coincided with the bacterial peak, whereas in CONV bacterivorous fauna were drastically reduced by soil fumigation. Nevertheless, the bacterial peaks were similar in CONV and INT, indicating that bacteria were not controlled by bacterivores.

Nitrogen mineralisation was relatively low in winter. The increased bacterial growth in February and March, and in September appeared to enhance immobilisation rather than mineralisation of N. During the growing season from April to the end of August, bacterial growth was relatively low and N mineralisation was relatively high. This probably resulted from bacterivore feeding and from substrate- or nutrient-limited bacteria with a low growth efficiency. Considerable mineralisation rates after harvest confirmed the need for measures to stimulate immobilisation during periods without crop uptake.

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^☆: Communication No. 57 of the Dutch Programme on Soil Ecology of Arable Farming Systems.

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Dynamics of microorganisms, microbivores and nitrogen mineralisation in winter wheat fields under conventional and integrated management☆

Abstract

J. Microbiol. Methods

Soil Biol. Biochem.

Soil Biol. Biochem.

Agric. Ecosyst. Environ.

Soil Biol. Biochem.

Soil Biol. Biochem.

Soil Biol. Biochem.

Agric. Ecosyst. Environ.

Agric. Ecosyst. Environ.

Soil Biol. Biochem.

Soil Biol. Biochem.

Agric. Ecosyst. Environ.

Agric. Ecosyst. Environ.

Quantities of plant nutrients in the microbial biomass of selected soils

Soil Sci.

Europium chelate and fluorescent brightener staining of soil propagules and their photomicrographic counting

Soil Biol. Biochem.

Separation and purification of bacteria from soil

Appl. Environ. Microbiol.

Buoyant densities and dry matter contents of microorganisms: conversion of measured biovolume into biomass

Appl. Environ. Microbiol.

Protozoan grazing, bacterial activity, and mineralisation in two-stage continuous cultures

Appl. Environ. Microbiol.

The survival of coryneform bacteria during periods of prolonged nutrient starvation

J. Gen. Microbiol.

The Dutch Programme on Soil Ecology of Arable Farming Systems. I. Objectives, approach and some preliminary results

Ecol. Bull., Copenhagen

Biomass, composition and temporal dynamics of soil organisms of a silt loam soil under conventional and integrated management

Neth. J. Agric. Sci.

Mineralisation of manure nitrogen—correlation with laboratory indexes

Soil Sci. Soc. Am. J.