Soil properties, crop water use and cereal yields in Botswana after additions of mulch and manure

• Published in: Field crops research Vol. 30; no. 1; pp. 97 - 109
• Main Authors: Carter, D.C., Harris, D., Youngquist, J.B., Persaud, N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.1992
• Subjects: ABONOS; BOTSWANA; CONTENIDO DE AGUA EN EL SUELO; CROP YIELD; CUBRIMIENTO DEL SUELO; ENGRAIS; FERTILIZERS; MULCHING; PAILLAGE; PENNISETUM TYPHOIDES; PROPIEDADES FISICO-QUIMICAS SUELO; PROPRIETE PHYSICOCHIMIQUE DU SOL; RENDEMENT DES CULTURES; RENDIMIENTO DE CULTIVOS; SOIL CHEMICOPHYSICAL PROPERTIES; SOIL WATER CONTENT; SORGHUM BICOLOR; TENEUR EN EAU DU SOL; USO DEL AGUA; UTILISATION DE L'EAU; WATER USE
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/0378-4290(92)90059-I

The direct and residual effects on sorghum and millet yields and water use of adding manure (9 t ha −1) and mulching with stover (5 t ha −1) were assessed during three seasons at three sites in semiarid Botswana. In addition, measurements were made of some physical and chemical properties of the three soils, a sandy loam (termed a ‘hardveld’ because of a tendency to harden on drying) and two loamy sands (‘sandvelds’). Annual rainfall during the study ranged from 352 to 924 mm. Mulching increased the soil water content near the surface of the hardveld. Manuring increased the water-holding capacity of the seedbed on the sandy soils by 19 and 27%, although no effects on bulk density or infiltration rate were detected. Adding manure also increased the cation exchange capacity (CEC), the amount of phosphorus and the pH in many cases. Residual effects on CEC and pH were also noted. Mulching had little effect on yields. Manuring increased grain yield and total dry matter: water use ratio (WUR; kg total dry matter mm −1 water used), on the sandveld soils and the effects on yield persisted for three seasons. Results suggest that conditions for plant establishment were improved by adding manure, resulting in more vigorous seedlings. Fertility was enhanced, especially on the finertextured soils, both in the current season and in the long term. Too much or too little rainfall, however, prevented crops from benefiting from this higher fertility. Practical constraints to the exploitation of manure and mulch in Botswana are discussed.