摘要:

The bio-economic on-farm evaluation was conducted on resource-poor farmers' farms in the Orlu and Owerri Agricultural Zones in the rain forest belt of Nigeria in 1996 and 1997. It estimated the difference in profit or loss expected from the introduction of sweet potato at 6, 8 and 10 weeks after planting (WAP) as a complementary weed control measure to egusi in a yam/maize/egusi/cassava intercrop against the practice of two hand weedings (4 and 12 WAP). A randomized complete block design with five replications and forty farmers was used. Analysis of variance was used to assess the biological yields and partial budgeting used for the economic analysis while farmers' potential acceptability or rejection of the intervention was assessed by means of simple direct survey.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754872

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Nitrogen fixing bacteria,Azotobacter chroococcum, and phosphate solubilizing fungi,Aspergillus awamori, caused marked decrease in C:N ratio and increase in P concentration of vermicompost prepared from farm wastes and cattle dung withEisenia foetida.Inoculated microbial count was maximum (29.7 × 106g−1of vermicompostA. chroococcum; 18.7 × 103g−1of vermicompostA. awamori)on day 45. Similarly, the enzymes dehydrogenase and alkaline phosphatase showed maximum activity of 867.7 μg TPF g−1vermicompost h−1and 327.5 μg of p-nitrophenol released g−1vermicompost h−1, respectively, on day 45 and then declined on day 90. The phytohormone indole acetic acid was also detected in vermicompost, produced by microorganisms. Increase in P concentration and decrease in C:N ratio was higher in microbial and worm inoculated treatments than in the control, which indicates maturation of vermicompost.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754873

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Ergosterol is generally assumed to be one of the best indicators of fungal biomass and soil quality. The present case studies describe variations in ergosterol content in soil, sampled at three Danish farms. One is organically cultivated according to the biodynamical principles (ORG). The other two are conventionally cultivated, one with animal husbandry (CONV-H) and one with plant production (CONV-P). The analytical method combined extraction in a microwave oven, clean-up with a new SPE sorbent material (OasisTM), and quantification by HPLC. The average estimated concentrations of ergosterol were 1.66 μg g−1in ORG, 2.35 μg g−1in CONV-H and 1.13 μg g−1in CONV-P. These results correlated well with some of the important variables in the management systems of the soils (frequency of grass and clover, input of animal manure, total-C, frequency of ploughing). However, the exact causal relationships cannot be revealed using the case-study approach. The statistical analysis of the spatial variation in ergosterol across the field demonstrated very clearly that in some soils, small-scale (few cm2) variations in ergosterol concentrations may be quite large in comparison with large scale (few hundred m2) variations. This should be taken into account when planning the sampling strategy.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754874

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Low levels of available nitrogen often reduce the protein content and baking quality of wheat produced on organic farms. Wide row spacing was suggested as a solution for improving crop production under limited nutrient conditions. In field experiments spring and winter wheats were cropped in wide spaced rows (22 and 75 cm, single and paired) at several positions in the crop rotation of an organic farm. Grain protein content was significantly increased by 0.5 to 1.2% above the 9.0–10.7% in normal seeded stands. Sedimentation volumes of flour in sodium dodecyl sulfate solution, another indicator of baking quality, were closely related to grain protein up to 11.5%, where they reached their maximum value. Yields were lower at row spacing of 75 cm compared with full stands. Nevertheless single rows at a distance of 75 cm yielded 3 t ha−1and double rows 3.7 t ha−1. Competition by companion plants seeded between wheat rows not more than one month earlier than wheat affected yield but not grain protein. Strong interference, both in yield and grain protein, was effected by established non-legume living mulch. Competition by legumes resulted in moderate yield losses but additionally improved grain protein.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754875

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Significant differences in earthworm populations and soil properties were found in three sections of a farm at Haughley in Suffolk that, since 1939, had either an organic, a mixed conventional, or a stockless intensive arable regime. Compared with the mean earthworm population of a 1,000 year old permanent pasture of 424.0 m−2; an organic field had 178.6 m−2; a mixed field 97.5 m−2; and a stockless field 100.0 m−2. Species recorded were:Allolobophora chlorotica, accounting for most of the increase in the organic section;Aporrectodea caliginosa, dominant in the stockless section;Aporrectodea icterica; Ap, longa; Ap. nocturna; Ap. rosea; andLumbricus terrestris.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754876

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Seasonal availability of nitrogen (N) from composted cattle manure (CCM) and poultry manure (PM) was studied in incubations and in fields with a crop of iceberg lettuce and leeks at two sites in Sweden during two seasons. Release of N from CCM was delayed for about 8 weeks in incubated soil and in soil with a crop of leeks, and N availability remained at the mineral N content of CCM at application. After 8 weeks, available N in CCM increased. However, in soil with a crop of iceberg lettuce, available N increased earlier and available N from CCM, as well as from PM, peaked during rapid crop growth. Available N from PM, both in the field and in incubated soil, dropped to a minimum after about two weeks and then increased during the season. N availability decreased at the end of the cropping period for both crops and both manures. The traits of the course of seasonal N availability were similar in the field and in incubated soil for both manures. However, the rapid increase of available manure N during growth of iceberg lettuce differed markedly from incubated soil. Initial losses of N from PM, possibly by volatilization, were higher in incubated soil.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754877

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The weed flora on 57 arable fields on 17 farms employing organic farming was recorded. With the ordination technique pCCA (partial Canonical Correspondence Analysis) the relative importance of some farming practices was evaluated (crop, preceding crop, ± undersown ley, ± weed harrowing, ± weed hoeing, ploughing regime, ± compost, ± animal husbandry, ± biodynamic agriculture). The variables that explained most of the variation in the weed flora in fields (along with typical weed species) were the crops ‘beans and peas’ (analysed together;Centaurea cyanus), ‘ley as preceding crop’(Cerastium fontanum), ‘weed hoeing’, ‘fallowing in the preceding year’ (Lamiumspp.) and ‘animal husbandry’(Sinapis arvensis).A number of species considered endangered, rare or decreasing in Sweden were recorded on these farms, suggesting that organic farming can contribute to maintaining biodiversity in an agricultural landscape. The weed flora was also compared with that of unsprayed control plots in herbicide trials. Ranking of weeds according to either frequency or a pCCA both showed clear differences, with organic fields having much more weeds. Species typical of organic farming wereCentaurea cyanusandVicia hirsuta.There was a tendency for weed species that dominate in conventional farming to be more nitrophilous than those species characteristic in organic farming.

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754878

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754879

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754880

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.2000.9754881

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor