Soil characteristics, land suitability and effect of trachyte and basalt rock powders on maize ( <i>Zea mays</i>  L.) growth and yield on Fluvisols in Cameroon's Sudano-Sahelian zone (Central Africa)

Abstract. The Sudano–Sahelian zone of Cameroon, characterized by a low annual rainfall, faces challenges in soil fertility preservation due to agricultural intensification and unsustainable practices. This study aims to evaluate the effect of trachyte and basalt powders inputs on soil and maize yield in Guiring experimental farm in the Far-North Region of Cameroon. Fieldwork involved collecting and describing samples of trachyte, basalt, and soil and setting up the experimental design. In the laboratory, the ground rock samples underwent geochemical analysis, and the soil samples were analysed for their mineralogical and physicochemical properties. The experiment followed a completely randomized block design with six treatments and four replications as follows: T0 (control plot without fertilizer inputs); T1 (trachyte powder applied directly after sowing at 2000 kg ha−1, 2.0 kg per 9.6 m2); T2 (trachyte powder applied directly after sowing (2000 kg ha−1; 2.0 kg per 9.6 m2) + urea (104.2 kg ha−1; 100 g per 9.6 m2) at 06 weeks); T3 (basalt powder applied directly after sowing (2000 kg ha−1; 2.0 kg per 9.6 m2); T4 (basalt powder applied directly after sowing (2000 kg ha−1; 2.0 kg per 9.6 m2) + urea (104.2 kg ha−1; 100 g per 9.6 m2) at 06 weeks); and T5 (NPK fertilizer applied 2 weeks after sowing at 208.3 kg ha−1 combined with urea applied 6 weeks after sowing (208,3 kg ha−1; 200 g per 9.6 m2) + urea (104.2 kg ha−1; 100 g per 9.6 m2) at 06 weeks. Growth and yield parameters of maize, include germination rate, plant height, number of leaves per plant, stem diameter, ear length, ear diameter, ear weight, 100-grain weight, and grain yield (kg ha−1). The soil is sand-dominated with a neutral pH, and its clay fraction is composed of kaolinite, smectites, and sepiolite. It exhibits low levels of organic matter (2.6 %) and nitrogen (0.1 %) but has a moderate-to-high cation exchange capacity (22.1 cmolc kg−1) and an available phosphorus content (19 mg kg−1). This soil is classified as Ochric Dystric Fluvisols according to the WRB. Fertilization trials showed a significant improvement in maize growth and yield. For NPK + urea as 100 % relative yield (T5: 3165 kg ha−1), basalt + urea reached 93 % (T4: 2931 kg ha−1) and trachyte + urea reached 87 % (T2: 2764 kg ha−1) of the maximum yield, whereas the remineralizers alone resulted in relative yields of 81 % and 75 % for basalt (T3: 2559 kg ha−1) and trachyte (T1: 2363 kg ha−1), respectively, with the low performance of 20 % (646 kg ha−1) obtained in the control. Although treatments with conventional fertilizers resulted in comparatively higher yields, rock powders offer significant advantages by facilitating region-specific strategies that deliver environmental benefits, durable effectiveness, and improved affordability.