Relationship of Soil Qualities to Maize Growth Under Increasing Phosphorus Supply in Acid Soils of Southern Cameroon*1

A large array of soil properties influences plant growth response to phosphorus (P) fertilizer input in acid soils. We carried out a pot experiment using three contrasted acid soils from southern Cameroon with the following main objectives: i) to assess the main soil causal factors of different maize (Zea mays L.) growth response to applied P and ii) to statistically model soil quality variation across soil types as well as their relationships to dry matter production. The soils used are classified as Typic Kandiudox (TKO), Rhodic Kandiudult (RKU), and Typic Kandiudult (TKU). Analysis of variance, regression, and principal component analyses were used for data analysis and interpretation. Shoot dry matter yield (DMY) was significantly affected by soil type and P rate with no significant interaction. Predicted maximum attainable DMY was lowest in the TKO (26.2 g pot−1) as compared to 35.6 and 36.7 g pot−1 for the RKU and TKU, respectively. Properties that positively influenced DMY were the levels of inorganic NaHCO3-extractable P, individual basic cations (Ca, Mg, and K), and pH. Their effects contrasted with those of exchangeable Al and C/N ratio, which significantly depressed DMY. Principal component analysis yielded similar results, identifying 4 orthogonal components, which accounted for 84.7% of the total system variance (TSV). Principal component 1 was identified as soil nutrient deficiency explaining 35.9% of TSV. This soil quality varied significantly among the studied soils, emerging as the only soil quality which significantly (P < 0.05) correlated with maize growth. The 2nd, 3rd, and 4th components were identified as soil organic matter contents, texture, and HCl-extractable P, respectively.