Agriculture and Environment最新文献

The importance of millet to small farmers of the semi-arid areas of Nigeria is described. The particular farming system of these farmers, desiring very early grain harvest and long-stemmed varieties for building material, which has developed a methodology of water use for early, erratic rainfall is also described. This farming system is such as to preclude yield improvement by standard agronomic techniques. Attention is drawn to the essential need for understanding such farming systems before undertaking research. An alternative approach to improving millet by breeding for pest and disease resistance, reduced plant bulk, and improved grain protein quality, such that the varieties so produced can be easily absorbed into the farming system, is proposed.

The results of a 6-year grazing trial in open Tabor oak woodland, dominated by annual plants, were used for the determination of the dependence of productivity on climatic fluctuations. Stepwise multiple regressions between October–November, December–January and February–March rainfall and minimum December–January temperatures resulted in high correlation coefficients, explaining 76% of the variance in the unfertilized, and even 99% of the variance in the more intensively improved and fertilized, pastures. Legumes were more dependent on total rainfall but also highly responsive to N or P dressings, whereas grasses were more responsive to early rains, especially after N dressings.

This is the first study in any mediterranean annual grassland where such close correlations between climate and productivity could be determined. In the drier years this productivity is typical of semi-desertic biomes but in more favorable rainfall years it is well within the range of the subhumid woodland-grassland biome. This great responsiveness to climatic fluctuations was apparently of large adaptive importance in the evolution of these grasslands and has contributed much to their striking resilience and persistence as dissipative structures, “creating order through fluctuation”.

It was concluded that this great climatic dependence, as a major bottleneck for rational livestock production, can be overcome only by improving the efficiency of moisture utilisation by introducing deeper-rooted, drought resistant and summer-green folder shrubs and trees.

The problems of modern high input agriculture are presently causing some concern. The fundamental problem is an undermining of the energy efficient self-sustaining character of a biological system. The purpose of this paper is to suggest an alternative system called Ecological Agriculture.

This has seven requirements:

• 1.

  (1) It must be self-sustaining. It is managed to reduce losses to a minimum, and all by-products are recycled. Decomposers and nitrogen fixers are encouraged. Fertility is maintained by techniques such as humus application, crop rotations and correct treatment and application of farmyard manure.

• 2.

  (2) It must be diversified in order to fulfill (1) above, also to increase stability and maximise biomass production. The ratio of animals (including humans) to plants must therefore be appropriate.

• 3.

  (3) In order to maximise yields, limit the capital investment required and increase employment, the unit size should be small, but appropriate to local conditions.

• 4.

  (4) The net yield per unit area must be maximised. Appropriate techniques are outlined.

• 5.

  (5) It must be economically viable. Conventional agriculture in the west is heavily grant-aided. This alternative farming system is aimed to operate at a real profit.

• 6.

  (6) The farm products should be processed on the farm and sold directly to local consumers. Cottage industries would revitalise many country communities, particularly in the developing countries.

• 7.

  (7) It must be aesthetically and ethically acceptable.

Techniques employed to achieve these aims are described and discussed in relation to arable crops (rotations, manuring, control of pests and weeds, and yields) and grassland management. The concept of niche occupation and creation in relation to animal husbandry is explored. The different criteria used in animal breeding, and the ethical arguments involved with intensive animal husbandry are also outlined. Energy and its production on the farm, the processing of farm products and crops, conservation and utilisation of wild-life and woodland, and the social and political effects of ecological agriculture are discussed. Figures are given from a survey in Europe of farms managed along these lines.

This type of agriculture would be of particular value to developing countries to help them become more self-sufficient in food. It will become of much importance also in the developed world in the future. Figures are given from a test-case farm which show that such a farming system does work, and shows promise for development.

Environs of Hepatics were compared and contrasted by both epiphytic and non-epiphytic distribution and coverage for seven different collection stations near Beech Fork Lake in Wayne County, WV, U.S.A. It is predicted that the selective harvest of timber will usually cause a decrease in hepatic species diversity, as timbering is an infrequent activity that causes intensive disturbance over a widespread area.

Hepatic populations of creekbanks and ravines are likely to be most severely affected by timber harvest because of the unusually high species diversity associated with such areas. Timbering of dry ridges and floodplains would probably have minimal effects on hepatics because species diversity is typically low in these areas of high environmental stress. A few species of broad ecological tolerance and short life cycles would be expected to increase coverage as a result of the added stress.

Frullania eboracensis Gott. was found to have the broadest ecological tolerance of all hepatics encountered in the study. Leucolojeunea clypeata (Schwein). Evans and Radula obconica Sull. demonstrated the highest environ specificity. A second paper will deal with the actual effects of logging.

Dust from the air of a swine confinement building was collected with an electrostatic precipitator made of glass. The odorous compounds were extracted from the dust with wet diethyl ether. Acids were removed from the ether with sodium carbonate solution, converted to decyl esters, and analyzed by capillary gas chromatography. Phenols were next removed from the ether by passage through a column containing sodium hydroxide. The phenols were quantified by gas chromatography of their trimethylsilyl esters. Carbonyls were converted to trichlorophenylhydrazones and quantified by gas chromatography. Results of typical analyses are presented, and the mechanism by which dust amplifies the odor of swine house air is discussed.