Influence of fertiliser application on the occurrence and colonisation of arbuscular mycorrhizal fungi (AMF) under maize/Centrosema and sole maize systems

Abstract

Soil fertility management practices can influence colonisation of crops by arbuscular mycorrhizal fungi (AMF) and their abundance. The effects of different rates of nitrogen-phosphorus-potassium (NPK) fertiliser on AMF occurrence and colonisation were studied in maize/Centrosema pascuorum and sole maize systems. The NPK treatments were at rates (kg/ha): 0-10-30, 45-10-30, and 0-0-0 (control). The AMF spore populations were enumerated by direct counting under a microscope. Nutrient uptake was calculated as the product of nutrient concentration and shoot dry weight, and maize yield was estimated per ha. In the maize/Centrosema system, spore count, AMF colonisation, and nutrient uptake (except N) decreased with NPK 45-10-30 compared with 0-10-30, although maize yields were comparable at the two fertiliser levels. In the sole maize system, fertiliser application did not influence AMF spore abundance, but colonisation, nutrient uptake, and crop yield increased significantly (P < 0.05) with NPK 45-10-30. Maize yield increased by 1200% under the maize/Centrosema system compared with sole maize at NPK 0-10-30. The lowest values for all parameters were obtained under the control treatments. Colonisation of AMF, nutrient uptake, and maize yield were positively correlated. The maize/Centrosema system can maximise AMF benefits to increase yield and also reduce fertiliser input into agricultural soils, while application of N fertiliser is important to increase yield in the sole maize system.