Atmospheric Demand for Water (B. Blad). The Soil as a Water Reservoir (S. Thein). The Role of Water in Plants (N. Turner and G. Burch). Alfalfa (G. Heichel). Bean (A. Halterlien). Corn (R. Waldren). Cotton (W. Jordan). Peanut (K. Boote). Potato (G. Kleinkopf). Rice (F. Turner and G. McCauley). Sorghum (D. Krieg). Soybean (D. Ashley). Sugar Beet (S. Martin). Sugar Cane (G. Gascho and S. Shih). Wheat (M. Kirkham and E. Kanemasu). Glossary. Index.
Foreword. Part I. Environment and natural resources. 1. Dry climates and their world distribution. 2. Climatic factors and their effect on crop production. 3. Soils of the dry zones. 4. Water resources, conservation and development. Part II. Crops under moisture stress. 5. Crop-water relations. 6. Plant adaptations to moisture stress. 7. Crop introduction and breeding for drought-prone areas. Part III. Land use and farming systems. 8. Agricultural systems in dry regions and their evolution. 9. Sustainable agriculture in dry regions. Part IV. Soil and crop management. 10. Soil fertility. 11. Mineral plant nutrition and fertilizer use. 12. Irrigation: principles and practice. 13. The maintenance of a permanent irrigation agriculture. 14. Tillage. 15. Plant population and planting geometries. 16. Crop sequences and associations. Part V. Crop protection. 17. Weeds and their control. 18. Insects and other plant pests. 19. Plant diseases. Index.
ABSTRACT Kudeyarov, V.N., 1991. Compensation for organic carbon loss from soil at nitrogen fertilizer application. Under conditions of intensive application of nitrogen fertilizers the disbalance of both N and C intrasoil flows was observed. Natural stores of organic carbon are not sufficient to immobilize residual mineral nitrogen pool formed due to nitrogen fertilizer application. Fresh biomass and easily decomposed metabolites with the increased content of nitrogen, which in its turn is easily mobilized in the mineral form, are accumulated. As a result, application of nitrogen fertilizers does not contribute to accumulation of organic substance in soil. In the field experiment carried out with 15 N-fertilizer the amounts of additionaly mobilized organic nitrogen and carbon compounds have been determined. It was shown that the value of extra mineralized carbon was 617 kg·ha −1 under application of 120 kg·ha −1 of fertilizer nitrogen. Probably to equilibrate the flow of mineral nitrogen in soil without formation of its excess, it is necessary to apply not less than 5 kg of organic carbon fertilizer per each kg of mineral fertilizer nitrogen.
Twenty-two sites representing five major soil textural classes, ranging from sandy loam to clay loam, in the county of Essex, in the United Kingdom were used to assess the effect of carbon and nitrogen in the organic matter on the supply of soil derived nitrogen to winter wheat in the 1985-86 cropping season. In twenty of these sites, wheat yield limitation due to insufficient nitrogen was determined by measuring the response to spring applications of fertiliser nitrogen. The influence of carbon and nitrogen of the soils on the mineral nitrogen supply and the associated effect on the yield and fertiliser nitrogen requirement are discussed. Grain yields, when the crops depended solely on soil derived nitrogen and the increase by the addition of optimum fertiliser nitrogen were better accounted for by the mineral nitrogen in the profile, despite its being a transient property in contrast to the more permanent properties of organic carbon and nitrogen.
Kolář L., Říha V., Tichý R., 1991. Effect of chemical properties of soil on humification of organic soil matter with respect to organic and mineral phosphorus fractions. Tight relationship betwen soil phosphorus and the parameters determining the quality and quantity of humus has been unambiguously proved in both the fertilized and unfertilized variants. Fractionation of organic phosphorus in the individual variants of the experiment has shown a substantial shift of phosphorus caused by mineral fertilization and the addition of easily decomposable source of carbon. Phosphorus in specific organophosphates (i.e., in humic and fulvic acids) was highest in the fertilized variants enriched with an easily accessible source of carbon and trace elements and pH-adjusted by liming. Phosphorus in nonspecific organophosphates (phytin, etc.) was highest in the same but unlimed variants.
The behaviour and availability of soil organic-C and -N were studied by means of soil particle-size fractionation techniques. In a first experiment, three soils were incubated with 14C-glucose or 14C-cellulose and K15NO3 for 104 weeks at 28°C and were fractionated at different sampling dates. The radioactivity was preferentially incorporated in the sand and coarse clay fractions for the cellulose treatment, and in the coarse clay, light silt and soluble fractions for the glucose treatment. All fractions for the glucose treatment and the sand fraction from the cellulose treatment were responsible for the mineralization of organic-14C during incubation. With the glucose and cellulose treatments, organic-15N was incorporated in the coarse clay, light silt and soluble fractions, and inorganic-15N produced during incubation was derived essentially from mineralization of these fractions. In a second experiment, 15N labelled soil materials (0-2, 2-20, 20-50, 50-200 μm fractions and whole soil) were then separately incubated for 224 days at 28 °C in shaken liquid media. For the calcic cambisoil, the labelled-N contained in the clay and sand fraction was more available than in the silt fraction. For the loamy soil, all fractions exhibited comparable 15N mineralization rates, except for the 20-50 μm fraction. At the same time, the non-labelled-N present in all fractions appeared to be less mineralizable than recently immobilized 15N.
Apfelthaler, R., 1991. Development of humus during the past Humus et Planta Symposia The tradition of Humus et Planta Symposia was founded in the year 1957 when first conference was held in Poznan (Poland) due to the joint activities of prof. Dr. S. Prát and prof. Dr. S. Guminski. At that time physiological effect of humus constituents on plants, animal and men were proved. The scientists tried to explain these effects and hoped to trace (by means of new 14C technique) the route of humus substances from soil into plant tissues and to determine the participation of humus constituents in the plant metabolism. Prof. Prát's theory of free radicals in humic acids was later confirmed by other authors by direct demonstration of free radicals. The growing interest in the symposium was illustrated by increasing number of submitted papers: from 42 in the year 1961 to 243 in 1988 at the IXth symposium. During this period importance of various topics has been changed. Problems concerning effects of humic substances on plant physiology became less frequent while paper dealing with relationship between soil management and fertility, biological activities, decomposition processes and chemical structure and physiological properties of humus substances represented the dominating interests of symposia participants till now. Transformation processes and transformation rates of soil organic matter constituents has been commonly held as more important than the humus content itself; contruction of mathematical models of C and N turnover offered new quality of control of soil management. Not very widespread, but of great importance, behaviour of xenobiotics in the soil has been discussed at the recent symposia. The necessity of saving of undisturbed environmental conditions especially of the soils become the more respected point of view in studying the transformation of organic substances in the soil and the interactions between humic substances and plants.
The disposal of olive oil waste waters (O.O.W.W.) is a typical and still increasing problem in the Mediterranean Area, where 1.4-1.8 million tons of olives are processed every year. The organic matter, that constitutes the polluting load of such a waste, may be considered as a potential soil fertilizer. This paper discusses the properties of the O.O.W.W. in view of their possible use in agriculture. Both the negative action due to polluting and phytotoxic compounds and the beneficial one due to the organic matter and mineral content have been taken into consideration. Although a final conclusion cannot be drawn, land application of O.O.W.W. generally improves the global fertility status and productivity of soil by governing nutritional and biological equilibria in the soil-plant system. Considering the available literature, general remarks can be made as follows: Olive mill waters enrich the soil with free living nitrogen fixers, stimulate microbial metabolism and sometimes improve tilth and crop yield. An improvement in the soil aggregate stability has been reported too. The organic load generally decreases from the surface down to about 100 cm depth. Furthermore, a suppressive action against some soil pathogens has been reported. Concerning the negative effects, the phytotoxicity recorded when waste waters are supplied disappears after a variable period (2-12 weeks) depending on the amount of waters supplied, on the soil properties and culture. The soil homeostatic power is able to control the possible harmful effects due to polluting substances, particularly phenols.
ABSTRACT Scharpenseel, H.W., Neue, H.U. and Singer, St., 1991. Biotransformations in different climate belts; source-sink relationships. Biotransformations in soils, acting as a compartment of the carbon cycle, contribute in comparison with the total biogeochemical carbon pool of ca 75 million GT carbon a minute fraction only; the whole humus-C-pool of ca 2.000 GT carbon represents but ca 25 ppm. But this pool is extremely important for sustaining terrestrial life. The CO 2 concentration of the atmosphere, the dominating determinant of autotrophic biomass productivity, changed throughout geological history considerably with a long-time-scale decreasing trend till a trend inversion with the begin of the industrial age. Source – sink relationships vary in different climate belts, showing a maximum carbon sequestration within the soil humus pool of legume – grass covered Mollisols or, focused on C in the living biomass pool, in tropical rain forests, astonishingly, both on a comparable level of magnitude. Rates of oxidative and reductive biotransformation, exceeding the abiotic/protolytic and photochemical decomposition rates, have been assessed in different ecosystems, using unifoimly 14 C-labeled plant material/soil organic matter. They depend primarily on temperature, moisture, soil pH and -Eh and on the inorganic complexing matrix. Reductive biotransformation, source of CH 4 and eventually N 2 O, receives increasing attention due to the contribution it renders in ca 630 mil hectare of wetlands, including the rice soils, to the climate change promoting greenhouse effect. The feasibility of engineered photosynthesis for channeling excessive CO 2 into sequestering land use systems, such as Azolla and BGA's (blue green algae) in wetlands, mangroves, coral banks or humus of legume-grass vegetation is under scrutiny. Otherwise, modeling results point to a state of overcompensation of CO 2 -release due to deforestation/slash and bum by the enhanced biomass production accrued from CO 2 -fertilization effects. Field experiments/ecosystem analysis work are tracing the soil organic matter dynamics via a refined compartmental approach, applying the Jenkinson or the Century model.
The paper reviews current research concerning the accumulation of allelochemicals as influenced by microflora, kind and maturity of decomposed plant tissues as well as type of soil. On the basis of results from our investigations, the paper also discusses the interrelationship between the dynamics of bacterial and fungal development and formation of inhibitors from young rye and wheat plants undergoing decomposition in light and heavy soils. The interrelationship was found particularly conspicuous during the first several days of sample incubation. Rye autoinhibitory potential was higher than that of wheat. It was found that, in particular, zymogenic, macrotrophic bacteria and fungi are responsible for the formation of allelopathic inhibitors.
Saiz-Jimenez, C., 1991. Applications of pyrolysis-gas chromatography/mass spectrometry to the study of soils, plant materials and humic substances. A critical appraisal. The selective thermal breakdown of complex macromolecular materials can readily be brought about by analytical pyrolysis. The technique combines thermal degradation, separation and identification of pyrolysis products. From the different separation and/or identification methods envisaged in the literature, only pyrolysis-gas chromatography and pyrolysis-gas chromatography/mass spectrometry are taken into account in this critical appraisal. Although structural investigation of soil humic substances can be achieved by many modern analytical techniques, pyrolysis-gas chromatography/mass spectrometry has been shown to provide relevant, reproducible, and fairly complete information.
ABSTRACT Kozak, J., Valla, M., Prokopec, O. and Vacek, O., 1991. Prediction of the role of soil organic matter and some other soil characteristics in herbicide adsorption. The effect of soil properties on some herbicide adsorption by different soils was investigated and evaluated by means of multivariate statistical methods, e.g. regression and correlation analysis. Adsorption was characterized by the K-values (Freundlich adsorption isotherm) and the A max value (Langmuir adsorption isotherm). The following four soil characteristics proved to be appropriate for the estimation and prediction of the adsorption: clay content, C ox content, pH KCl and C.E.C. value. Using suggested procedure, the adsorption could be predicted with high probability. Organic matter played the most important role in the adsorption of all herbicides under study.
