Some effects of crop rotation on the productivity of crops on a red earth in a semi-arid tropical climate

Bennison, R. H.; Evans, Donald L.

doi:10.1017/s0021859600014891

Cited by 3 publications

(1 citation statement)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was quite evident that the sorghum crop in non-fallowed plots was suffering from nitrogen deficiency, as shown by typical foliage symptoms, general lack of vigour and reduced tillering. Bennison and Evans (1968) have clearly demonstrated the beneficial effect of a season's bare fallow on available nitrogen levels, but unfortunately this could not be detected by soil analysis because the samples were too large. Preliminary data (Legg-personal communication) indicated that high mineral (NH 4 ++NO 3 -) nitrogen (<3O ppm) was present in the top 2 cm.…”

Section: Resultsmentioning

confidence: 99%

Moisture Conservation by Fallowing in Botswana

Whiteman¹

1975

Ex. Agric.

View full text Add to dashboard Cite

Low and unreliable rainfall, combined with high summer evaporation rates, frequently lead to poor yields and crop failure in Botswana agriculture. Over three test years it has been shown that the soil can store up to ioo mm. of available moisture at planting time, which represents about half the water requirement of a crop of sorghum, and the balance is likely to be met (P = 0-05) during the current growing season. Sorghum grain yields have been doubled (2007 kg./ha.) after fallow compared with 1028 kg./ha. after non-fallowed pre-treatments. The advantages of a farming system based on a bare summer fallow are discussed, and reference is made to the implications of its wider adoption.The success of whole farming systems in various semi-arid regions (Australia, the Western states of North America and Canada, and the Middle East) is based on the use of a bare fallow in the rotation, i.e. keeping fields free of vegetation for the whole, or part, of a season. The improved yield of the following crop has been shown to be very largely due to a better supply of soil moisture and nitrogen, compared with yields on continuously cropped land (Staple, i960). The relative importance of these two factors depends on whether the wet season occurs in the summer or winter, the nature of the soil, the pattern of rainfall in individual years and the time of planting.Much of southern Africa is classified as semi-arid, yet fallowing is not practised and appears not to have been evaluated. In Botswana, crop yields fluctuate with the season's rainfall, with failure or low yields in about two years out of every five. This is illustrated by the fact that the coefficient of variation of mean trial yields for a particular crop over many seasons (50-60 per cent) is considerably higher than the coefficient of variation for varieties within a trial in any particular season (15-25 per cent). Lack of moisture is the most important limiting factor, and the immediate requirements are therefore to find ways of Maximising infiltration of rainfall, Improving conservation of this stored moisture, and Increasing the efficiency with which this conserved moisture is used. This paper reports an experiment designed to assess the effect of a summer fallow on sorghum yields, with comments on its possible usefulness in Botswana. MATERIALS AND METHODSIn 1969, six treatments were laid down in a randomized block design with six replications: * Present address: Sunnyside, Down End, Drayton, Portsmouth PO6 iHX, Hants. 20

show abstract

Section: Resultsmentioning

confidence: 99%

Moisture Conservation by Fallowing in Botswana

Whiteman¹

1975

Ex. Agric.

View full text Add to dashboard Cite

show abstract

Prospects of soil moisture conservation by fallowing in areas of medium agricultural potential in smallholder farming

Njihia¹

1988

Agricultural Water Management

View full text Add to dashboard Cite

Breeding of maize for low rainfall areas of Kenya:1. The reliability of yield of early and later maturing maizes

Dowker

1971

J. Agric. Sci.

View full text Add to dashboard Cite

A trial to compare the reliability of yield of a quick maturing maize (Taboran) with the medium maturity local maize was carried out at two low rainfall sites in Southern Province, Kenya, from 1957 to 1961. Each variety was grown at two spacings, giving plant densities of 1-8 and 3-6 pl./m a . Results showed a consistent difference in 'days to 50 % silking', Taboran being on average 17 days earlier than Local White. There was no overall difference between varieties or spacings in yield per ha. There were highly significant interactions of seasons with varieties and with spacings. These were interpreted in terms of different linear yield/rainfall relationships for each variety and each spacing. A variety/spacing interaction was also demonstrated.Analysis of components of yield showed that similar linear relations between rainfall and each yield component obtained. There were significant differences between varieties and between spacings in both mean number of cobs per plant and yield per cob. Taboran had a higher mean number of cobs per plant and Local White a higher mean yield per cob. Seasons x varieties interactions were again interpreted in linear regression terms. Earliness of the Taboran variety often enabled plants to produce silks before development was arrested by drought and so was responsible for its relatively high mean number of cobs per plant in low rainfall seasons, giving it an advantage over Local White in yield per unit area in such circumstances. Taboran was shown to have a potential value in local agriculture, because of its consistency of yield. The expected advantage or disadvantage of Taboran over Local White was calculated for an area of known rainfall from the respective yield/rainfall regressions and the seasonal rainfall probabilities.Selection for earliness was shown to be of basic importance in a breeding programme for the low rainfall areas. Within a specified early maturity range, selection for yield improvement through the yield per cob component could be practised. A maturity length similar to Taboran would ensure a high value of mean cobs per plant in low rainfall season, i.e. confer the necessary reliability of yield.

show abstract

Some effects of crop rotation on the productivity of crops on a red earth in a semi-arid tropical climate

Cited by 3 publications

References 13 publications

Moisture Conservation by Fallowing in Botswana

Moisture Conservation by Fallowing in Botswana

Prospects of soil moisture conservation by fallowing in areas of medium agricultural potential in smallholder farming

Breeding of maize for low rainfall areas of Kenya:1. The reliability of yield of early and later maturing maizes

Contact Info

Product

Resources

About