Nitrogen Studies on the Irrigated Soils of the Sudan Gezira

Jones, Thomas A.

doi:10.1111/j.1365-2389.1957.tb01883.x

Cited by 11 publications

(9 citation statements)

References 17 publications

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“…As mentioned earlier, the 'combined-rotations' experi-In view of this, and since plant growth within one season and between rotations is markedly associated with soil-nitrate differences (Tothill, 1948)) it is logical to conclude that mineralized nitrogen and organic nitrogen in Gezira soil do not function in close interdependence. This claim was made in a previous publication (Jones, 1957)) and the present paper offers further supporting evidence.…”

Section: Discussionsupporting

confidence: 91%

“…IN a previous paper (Jones, 1957) the author described the changes in organic-nitrogen content that occurred under three-course rotational cropping in Sudan Gezira soil. The field experiment used for the investigation was one of the long-term rotation experiments at the Gezira Research Farm, Wad Medani, Sudan; but the practical value of the experiment in terms of the general agriculture of the area was limited.…”

mentioning

confidence: 99%

“…Sampling was done at regular intervals throughout the year, and this paper presents the results for the seasons 1949-50,1950-1, and 1951-2. All sampledmaterial was treated as described previously (Jones, 1957) and results are expressed on an oven-dry basis.…”

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Nitrogen Studies on the Irrigated Soils of the Sudan Gezira Ii. Extended Fallowing in Cotton Rotations

Jones¹

1958

Journal of Soil Science

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Seasonal fluctuations in organic nitrogen and nitrate nitrogen in the soil of the Sudan Gezira are described under conditions of extended fallowing in cotton rotations. Statistically, results show that soil organic nitrogen is independent of rotational phase. Cotton yields are not limited by the content of organic nitrogen in the soil, but by soil physical conditions which improve by extended fallowing. Evidence is presented to show that soil organic nitrogen and nitrate nitrogen in this soil do not function in close interdependence. This conclusion was drawn in other work previously published.IN a previous paper (Jones, 1957) the author described the changes in organic-nitrogen content that occurred under three-course rotational cropping in Sudan Gezira soil. The field experiment used for the investigation was one of the long-term rotation experiments at the Gezira Research Farm, Wad Medani, Sudan; but the practical value of the experiment in terms of the general agriculture of the area was limited. Although the frequent cropping involved in a three-course rotation might economically offer a better gross agricultural output than a rotation containing a longer fallow eriod, it was known that under the intense of better weed control through cessation of watering. What was not known, however, was the optimum length of fallow.In order to investigate this point a 'combined-rotations' experiment (Crowther and Cochran, 1942) was laid down, and the present paper describes a study of the changes in soil organic nitrogen and nitrate nitrogen that occur under extended fallowing on this experiment in the Gezira. The experiment was planned to provide a com arison between ing cotton together with the variations from inclusion of intervening dura (Sorghum oulgare) and lubia (Dolichos Zablab). Ten rotations were involved with a total of thirty phases. The different treatments were completely randomized in each of five blocks making a total of 150 sub-plots. Each sub-plot was 4 feddan" in area.Data for the dura and lubia variations are not included in the present paper, which is restricted to an examination of soil samples taken from all hases of the following rotations: A, continuous cotton; M, cotton an one ear fallow; G, cotton and two years fallow; K, cotton and three years fa low. The five rotation replicates per phase were sampled for * I feddan = 1.038 acres. heat of the Central Sudan P allowing was highly beneficial and permitted one-, two-, three-, and four-course rotations in terms o F fallows follow-

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Nitrogen Studies on the Irrigated Soils of the Sudan Gezira Ii. Extended Fallowing in Cotton Rotations

Jones¹

1958

Journal of Soil Science

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“…Analysis of organic carbon was undertaken on the identical 'threecourse-rotations' samples used in the organic-nitrogen study (Jones, 1958), although carbon analyses were not commenced until the 194 -o Walkley-Black method as described by Pi er (194z), but modified by Black values' have been corrected for 75 per cent. recovery although the arbitrary nature of this figure is appreciated.…”

Section: Experimental and Resultsmentioning

confidence: 99%

“…Seasonal variations in organic and nitrate nitrogen and the influence of extended fallowing in cotton rotations on these constituents have been previously described (Jones, 1957(Jones, , 1958.…”

Section: Discussionmentioning

confidence: 99%

Carbon Studies on the Irrigated Soils of the Sudan Gezira

Jones¹

1958

Journal of Soil Science

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The seasonal variation in the organic-carbon content of Gezira soil under irrigated rotational cropping has been studied over three successive years. Emphasis has been placed on the cotton phases of the rotations. Significant differences in organic carbon occurring between rotations did not produce differences in degrees of nitrogen fixation. It is suggested that fixation and mineralization of nitrogen occur so rapidly in this soil that it is not possible by chemical analysis to determine the amount of nitrogen fixed.Seasonal changes in organic-carbon content display a phase of slow fluctuation when the soil is wet and carries a crop, and a phase of rapid fluctuation when the soil is bare, dried by insolation, and cracked. Attention is drawn to this phase and to the need for better understanding of the associated phenomena which contribute to the maintenance of high fertility in these arid soils.As a further contribution to a better understanding of the organic cycle in the arid irrigated soil of the Sudan Gezira, this paper describes a study of the seasonal variations in organic carbon under three-course rotations. Seasonal variations in organic and nitrate nitrogen and the influence of extended fallowing in cotton rotations on these constituents have been previously described (Jones, 1957, 1958). Experimental and ResultsAnalysis of organic carbon was undertaken on the identical 'threecourse-rotations' samples used in the organic-nitrogen study (Jones, 1958), although carbon analyses were not commenced until the 194 -o Walkley-Black method as described by Pi er (194z), but modified by Black values' have been corrected for 75 per cent. recovery although the arbitrary nature of this figure is appreciated. All results are quoted on an oven-dry basis. Analysis of variance was carried out on each season's figures and differences in organic-carbon content were assessed at P = 0.05 level of significance. Significant differences existed between rotations and between sampling dates. These are shown in Table I and Fig. I. There was no interaction between dates and rotations.TABLE I. 'Organic-carbon, Walkley-Black values' in p.p.m. of soil, as season. The detailed analytical procedure was essentially that o ? i t e Middleton (195 I) to suit local conditions. T R e 'organic-carbon, Walkleyrotational means over whole season Rotation

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Der Einfluß von Bewässerung und Fruchtfolge auf den Humus‐ und Stickstoffhaushalt sowie die Bodenproduktivität in der Gezira (Sudan)

Jagnow¹

1973

J Plant Nutrition & Soil

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The influence of irrigation and crop rotation on the humus and nitrogen balance and soil productivity in the Sudan Gezira. Yields of Sorghum and Cotton, but not of Dolichos increased up to 3 times from the 10th to the 30th year in an unfertilized, irrigated field experiment on a vertisol with crop rotations of Cotton, Sorghum and Dolichos, esspecially after preceding years of bare fallow. Nitrogen fixation by root nodules and asymbiotic fixation by Azotobacter and blue green algae are discussed as a cause of the increased soil productivity. In a field pot trial with 2.5 cm layers of flooded soil 75 ppm of nitrogen were fixed in 12 weeks by blue green algae. On fertilization with 0.1% K2HPO4 and 0.1% K2HPO4 + 50 ppm Na2MoO4 they fixed 244 and 290 ppm N respectively. Drying and reflooding the soil once to several times caused the N‐fixation to decrease steadily until it stopped with weekly dryings. Strong increases and decreases of organic C and N were observed in moist and also in dry field soil in different seasons as well as short term fluctuations of organic N in dry field soil.

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Nitrogen Studies on the Irrigated Soils of the Sudan Gezira

Cited by 11 publications

References 17 publications

Nitrogen Studies on the Irrigated Soils of the Sudan Gezira Ii. Extended Fallowing in Cotton Rotations

Nitrogen Studies on the Irrigated Soils of the Sudan Gezira Ii. Extended Fallowing in Cotton Rotations

Carbon Studies on the Irrigated Soils of the Sudan Gezira

Der Einfluß von Bewässerung und Fruchtfolge auf den Humus‐ und Stickstoffhaushalt sowie die Bodenproduktivität in der Gezira (Sudan)

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