Descubre por qué frutas y verduras han perdido hasta un 50 % de sus nutrientes en los últimos 70 años y la urgencia de recuperar la salud del suelo.

Arbuscular mycorrhizal fungi, important soil phosphorus mobilizers in natural systems, become gradually impoverished by high fertilization and tillage in conventional agricultural systems. The effects of management practices on their capacity to transfer phosphorus to crops have however not been directly measured under field conditions and their contribution to crop nutrition when management changes remain unknown. We compared the specific contribution of native arbuscular mycorrhizal fungi to P uptake of oats under long-term conservation agriculture or conventional tillage and explored whether 19 years of conservation agriculture had improved their P transfer capacity to oat plants. We expected that preserved mycorrhizal communities and hyphal networks under conservation agriculture increased the transfer of labeled P from a confined location in the soil to oat shoots. Local soil labeled with 33P was buried between rows in mesh bags that excluded roots or allowed roots and mycelium. Plant and mycorrhizal development, and 33P transfer to shoots, were followed in mesh bags and shoots from seedling to grain filling stage. 33P transferred to shoots and root-length specific 33P uptake were significantly higher in the conservation agriculture than in the conventional tillage treatment. 33P transfer by conventional tillage roots was similar to transfer by non-mycorrhizal roots. 33P transfer to oats plants was positively related to root length and root colonization by arbuscular mycorrhizal fungi. Our results provide evidence of higher P transfer capacity of mycorrhizal oat roots when native arbuscular mycorrhizal fungi communities and their networks were preserved through long-term conservation agriculture. This is one of the few studies showing the otherwise hidden specific contribution of arbuscular mycorrhizal fungi to crop P nutrition under realistic field conditions and the first to document the improvement in 33P transfer when oat roots were colonized by local fungi from the soil under long-term reduced disturbance by tillage.