B6nassy, C., 1955. R6marques sur deux Aphelinid6s: Aphelinus mytilaspidis Le Baron et Aphytis proclia Walker. Annls l~piphyt. 6: 11-17. Lord, F. T. & MacPhee, A. W., 1953. The influence of spray programs on the fauna of apple orchards in Nova Scotia II. Oyster shell scale. Can. Ent. 79: 196-209. Pickett, A. D., 1946. A progress report on long term spray programs. Rep. Nova Scotia Fruit Grow. Ass. 83 : 27-31. Pickett, A. D., 1967. The influence of spray programs on the fauna of apple orchards in Nova Scotia XIV. Can. Ent. 97: 816-821. Tothill, J. D., 1918. The predacious mite Hemisarcoptes malus Shimer and its relation to the natural control of the oyster shell scale Lepidosaphes ulmi L. Agric. Gaz. Can. 5 : 234-239.

http://link.springer.com/content/pdf/10.1007/BF01976688.pdf

Soil enzymes: Kuprevich, V. F. & Shcherbakova, T. A.: Translated from the Russian edition (1966), published by the Indian National Scientific Documentation Centre, New Delhi 1971. 392 pp., offset printing from type script, paper cover. Obtainable from U.S. Department of Commerce, National Technical Information Service, Springfield, Va. 22151

CONTENTS I . Introduction . 11. Factors which influence microbial biomass . . . ( I ) Soil chemical factors . . . . . . . ( a ) Carbon and nitrogen limitation . . . . ( b ) Residue and nutrient amendment . . . (c) Influence of plants . . . . . . ( d ) Soil pH . . . . . . . . (e) Heavy metals and pesticides . . . . (2) Soil physical factors . . . . . . . ( a ) Soil texture and structure ( b ) Soil moisture and temperature (c) Seasonal fluctuations . . . . . . 111. Global distribution of microbial biomass . . . ( I ) Relationship with soil chemical factors and macroclimate

A comparative assessment of factors which influence microbial biomass carbon and nitrogen levels in soil

A review of the use of composted municipal solid waste in agriculture

http://nhjy.hzau.edu.cn/kech/ssyy/pdf/hvmet/7.pdf

A critical review of the bioavailability and impacts of heavy metals in municipal solid waste composts compared to sewage sludge.

This review reveals that crop residues of common cultivated crops are an important resource not only as a source of significant quantities of nutrients for crop production but also affecting soil physical, chemical, and biological functions and properties and water and soil quality. When crop residues are returned to the soils, their decomposition can have both positive and negative effects on crop production and the environment. Our aim as agricultural scientists is to increase the positive effects. This can only be achieved with the better understanding of residue, soil, and management factors and their interactions, which affect the decomposition and nutrient release processes. Data on nitrogen benefits and nitrogen recoveries from residues show that a considerable potential exists from residues, especially leguminous residues, not only in meeting the N demands of the succeeding crops, but also in increasing the long-term fertility of the soils. In addition, crop residues and their proper management affects the soil quality either directly or indirectly. Intensive cropping systems are very diverse and complex, so no one residue management system is superior under all situations. Ideally, crop residue management practices should be selected to enhance crop yields with a minimum adverse effect on the environment. It is suggested that in each cropping system, the constraints to production and sustainability should be identified and conceptualized to guide toward the best option. Multidisciplinary and integrated efforts by soil scientists, agronomists, ecologists, environmentalists, and economists are needed to design a system approach for the best choice of crop residue management system to enhance both agricultural productivity and sustainability.

Crop Residues and Management Practices: Effects on Soil Quality, Soil Nitrogen Dynamics, Crop Yield, and Nitrogen Recovery

Changes in enzyme activity levels, in biomass-C content, and in the rate of fluorescein diacetate hydrolysis were measured in a loamy soil to which solid municipal refuse had been applied as compost over a 3-year period at two different rates. Addition of the compost caused significant increases in the activity of all enzymes tested. The increases were much higher at 90 t ha-1 year-1 than at 30 t ha-1 year-1. Significant increases were also observed in the biomass-C content and in the rate of fluorescein diacetate hydrolysis. Significant correlations among changes in biomass-C content and the rate of fluorescein diacetate hydrolysis and the changes in all enzymes tested were found. Two activity indices were calculated; a biological index of fertility and an enzyme activity number. No correlations were found between the biological index of fertility and the changes in the various enzyme activities. However, significant correlations were found either between enzyme activity number and most of the changes in enzyme activity, or between the enzyme activity number index and the biomass-C content (r=0.850). The use of a new activity index, the hydrolysis coefficient, is proposed. This coefficient was significantly correlated with biomass-C content (r=0.925) and with the enzyme activity number index (r=0.780).

Enzyme activity and microbial biomass in a field soil amended with municipal refuse.

Changes in the content of C, N, P, and S in the soil biomass and in phosphatase, urease, protease, deaminase, and arylsulphatase activity, induced by amendment with municipal solid-waste compost, were determined in a clay loam soil during 1 year of incubation at 25° and 35°C.

Effect of the addition of municipal solid-waste compost on microbial biomass and enzyme activities in soil

The effects of imazethapyr, an imidazolinone derivative on the soil microbial biomass was investigated in a clay loam soil. Imazethapyr was applied in a field trial at the recommended field rate for soybean weeding, 50 g a.i. ha-1. In laboratory experiments the herbicide was incorporated at the field rate and 10-fold and 100-fold higher. In both the field trials and the laboratory experiments, the field rate of imazethapyr had no adverse effects on the microbiological processes tested. But at 10-fold and 100-fold higher rates, the herbicide decreased the biomass-C content and dehydrogenase activity and increased the hydrolytic capacity and protease and catalase activity. These findings suggest that there may be a risk in monocultural practices that require repeated herbicide treatments.

Effects of the herbicide imazethapyr on soil microbial biomass and various soil enzyme activities

Amylase, dehydrogenase, arylsulphatase and phosphatases activities were measured in a clay-loam soil amended with seven different crop residues. All enzyme activities, except phosphomonoesterase, were generally higher in the derived soil samples than in the original soil. Addition of tobacco and sunflower residues caused an increase on most of the enzyme activities while tomato residues increased only the amylase and phosphodiesterase activities.

Enzyme activities in a clay-loam soil amended with various crop residues

An investigation was carried out to analyze the chemical composition and enzymatic activity of five worm casts obtained from various animal dungs and municipal waste. The E4/E6 values for humic and fulvic acids were higher in all worm casts than in a typical Umbrian soil. Comparisons between worm cast, substrate and soil IR and NMR spectra demonstrated the humifying capacity of worms. Enzyme activity was high in all casts and only dehydrogenase seemed to be affected by lead concentration.

P. Perucci

Papers

Enzyme activity and microbial biomass in a field soil amended with municipal refuse.

Effect of the addition of municipal solid-waste compost on microbial biomass and enzyme activities in soil

Effects of the herbicide imazethapyr on soil microbial biomass and various soil enzyme activities

Enzyme activities in a clay-loam soil amended with various crop residues

Chemical composition and enzymic activity of some worm casts