摘要:

Studies were done with corn and cowpeas, cultivated using traditional methods. Both biological and economic yield advantages were computed. The advantage of the intercrop depended upon both the evaluation criterion utilized and the ecological background of the area in which the experiments were done. A clear intercrop advantage was obtained in the area which was intermediate fallow and not burned (“bush fallow”)- Equivocal results were obtained in the area which was slashed and burned (“forest fallow”). Both biological and economic criteria were utilized in evaluating the system.

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754383

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A survey involving a written questionnaire to 120 organic farmers and direct interviews with selected farmers was conducted to provide a preliminary assessment of the state of organic farming in California. A case study was made of apple production systems where some of the organic systems appeared to be economically viable. The lower yields of organic apples were offset by reduced input costs. It is concluded that expansion of organic agriculture in California is limited mainly by socio-economic factors.

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754384

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The Jones-Mollison method was applied to estimate bacterial and fungal biomass in arable soil. Also examined were: 1) applicability of the line-intercept method for estimation of hyphal length; 2) relationship between dispersion time of soil and microbial counts; 3) selection of staining dye and microscopy; 4) recovery of microorganisms added to soil; and 5) mean biovolumes. Sums of bacterial-fungal biomass estimated bimonthly for 14 months were 26–36, 36–48, 36–66 and 37–83 mg dry weight/100 g dry soil in a barley-peanuts field applied with well rotted artificial compost at a rate of 0, 20, 40 and 80 t ha−1, respectively. The biovolume-biomass conversion factor used was 0.22. Significant fluctuations of microbial biomass were observed in soil with compost. Bacterial biomass reached a maximum just after compost application in October, followed by a fungal maximum in March. Throughout the year fungal biomass was 1.7–7.1 times higher than bacterial mass. The apparent amounts of nitrogen temporarily trapped in bacterial and fungal biomass (nitrogen in maximum biomass minus that in biomass just before compost application) were calculated as 2.9 and 5.1, 4.4 and 33.5 or 9.7 and 50.9 kg ha−1in the plot applied with 20, 40 or 80 t ha−1of compost, respectively, when nitrogen content of biomass is assumed as 10% of dry matter.

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754385

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Beans and cowpeas planted outside the normal growing season were tested as green manure crops for a raised-field system in Tabasco, Mexico, similar to those used by the pre-Hispanic lowland Maya. All three cultivars suppressed weeds effectively. One cowpea cultivar added an appreciable amount of fixed nitrogen to the system but the addition was achieved at the expense of seed yield, due to lack of flowering.

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754386

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The effect of phosphorus on nodulation, dry matter yield and dinitrogen fixation (as determined by the15N technique) of bean plants (Phaseolus vulgaris) was evaluated in a field experiment at three growth stages. Application of phosphorus increased nodule mass, dry matter yield, nitrogen yield and dinitrogen fixation at all the three stages (i.e. flowering, pod-filling, and physiological maturity) but the effects of phosphorus were more pronounced at the flowering and pod filling stages. The highest dinitrogen fixation was recorded within the pod filling stage where phosphorus was applied. The results clearly demonstrate that availability of phosphorus can be an important factor in symbiotic biological nitrogen fixation by beans. For these studies the best sampling time appears to be within the pod-filling stage. A biological approach in solving phosphorus problems in symbiotic biological nitrogen fixation by grain legumes is suggested.

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754387

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The Labiatae is a large family of diverse morphology and habit. Almost all members contain phytochemicals, volatile oils which contribute variously to commercial value, problems of toxicity and allelopathic activity. Weed status in the Labiatae depends primarily on competition for environmental resources and on characteristics dependent on the phytochemical content. In a number of genera, notablySalvia, allelopathic activity has been documented.

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754388

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754389

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754390

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754391

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0144-8765    

DOI:10.1080/01448765.1983.9754392

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor