Tag Archives: Phosphorus

337-348 S. Benlahrech, G. Kac, M. Teffahi and S.M. Ounane
Influence of inoculation and phosphorus regimes on symbiotic nitrogen fixation and phosphorus use efficiency of Algerian cowpea (Vigna unguiculata L. (Walp.)) landraces
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Influence of inoculation and phosphorus regimes on symbiotic nitrogen fixation and phosphorus use efficiency of Algerian cowpea (Vigna unguiculata L. (Walp.)) landraces

S. Benlahrech*, G. Kac, M. Teffahi and S.M. Ounane

Integrative Breeding of Vegetable Production Laboratory, National High School of Agronomy, Avenue Hassen Badi, El Harrach, DZ16200 Algeria
*Correspondence: benlahrechsamia@gmail.com

Abstract:

To study the genotypic variation of cowpeas on plant growth and phosphorus (P) uptake which is a function of different P regimes in the soil rhizosphere, 6 landraces of cowpea commonly found in northern Algeria (NE4, NE10, NE11, NKT5, NKT7, NKB7) and 4 landraces from Sahara in southern Algeria (NAG4, NAG5, NAT2 and ND3) were studied during 2013–2014 in greenhouse. They were inoculated with Mesorhizobium sp. (S1), Bradyrhizobium sp. (S2) and co–inoculation (S1–S2) under three P treatments: no P supply (P0), soluble P (PP) and insoluble P (TCP). Only varieties commonly found in northern Algeria nodulated with soluble P (PP) and inoculation containing Mesorhizobium sp. (S1). As a result of the symbiosis, the use of S1 has significantly increased shoot dry weight by 22%, total P content by 20% and P use efficiency for symbiotic nitrogen fixation by 18% compared to no inoculation (T). The landraces from the northern of Algeria expressed a higher growth than those from Sahara in the south of Algeria, especially three of them (NE4, NE10 and NE11) who showed a high performance under all P regimes. We suggest that these three landraces may be useful for improving symbiotic nitrogen fixation in cowpeas when growth is limited by low–P soils and that they could contribute to sustainable farming systems through reduction of farmer’s dependence on fertilizers.

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63–70 E. Lauringson, L. Talgre, H. Roostalu and H. Vipper
The effect of tillage and crop rotation on the content of available nitrogen, phosphorus and potassium
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The effect of tillage and crop rotation on the content of available nitrogen, phosphorus and potassium

E. Lauringson¹, L. Talgre¹, H. Roostalu² and H. Vipper¹

¹Department of Field Crop Husbandry, Estonian Agricultural University, Kreutzwaldi 64, 1008 Tartu, Estonia; e-mail: ennlaur@eau.ee
²Department of Soil Science and Agrochemistry, Estonian Agricultural University, Kreutzwaldi 64, 1008 Tartu, Estonia; e-mail: roostalu@eau.ee

Abstract:

This research (A long-term field experiment from 1982 to 1997) was conducted at the experimental station of the Department of Field Crop Husbandry of the Estonian Agricultural University. The soil of the experimental site is moderately moist slightly podzolised sandy clay.
Insofar as field crop husbandry is concerned the soil should contain optimal amounts of available nutrients. If the level of available nutrients in the soil is low the plants will suffer and the yield will be low. A rise in soil available nutrient content leads to increased yield of crops, but only up to a certain level (optimal content). Thereafter, a further rise in soil nutrient content fails to effect any significant increase in the harvest.
The soils of the Eerika trial plot have optimal nutrient content and little need for fertilisation. After two crop rotations significant changes in nutrient content and location were observed in the ploughed layer. Compared to the nutrient content determined at the start of the trial period (1982), the greatest changes occurred in the soils under a crop rotation involving cereals, potato and a mixture of red clover and timothy, in which the supply of available phosphorus decreased by 19 mg kg-1 and that of potassium by 121 mg kg-1 on average after two rotations. Compared to the cereal rotation and the rotation containing 50% of cereals and 50% of potato the available phosphorus content dropped by 12–33% and the potassium content by 41–46% in the upper 25-cm soil layer.

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