Title: Leaf resorption and stoichiometry of N and P of 1, 2 and 3 year-old lucerne under one-time P fertilization
Authors: Jiaoyun Lu, Minguo Liu, Mei Yang, Junhong Xie, Huimin Yang*, Lingling Li
Journal: Soil & Tillage Research（农林科学1区, IF2020=4.601）
Abstract: Nutrient resorption is one of the key processes of a plant to conserve nutrients and to less depend on soil nutrient availability, which makes the plant more adaptive to adverse environments. Understanding of the effect of phosphorus (P) fertilization on leaf nutrient resorption of legume species is still limited. The aim was to test the responses of leaf nutrient resorption and stoichiometry to immediate and post effects of P fertilization in the Loess Plateau of China where soil P availability is largely restricted due to soil erosion and drought. Nitrogen resorption efficiency (NRE), P resorption efficiency (PRE), green leaf N:P (N:Pgr) and senesced leaf N:P (N:Psen) were investigated in 1–3 year lucerne (Medicago sativa L.), a widely used forage in this rainfed region. The NRE and PRE increased with stand age increase from 1 to 3 years. The P fertilization had no effect on NRE, but significantly affected PRE. The PRE increased with P fertilization in the first year and PRE was the highest at 60 kg P2O5 ha?1 in the second and third years. The N:Pgr decreased and N:Psen increased with stand age, suggesting more P limitation along lucerne growth. The one-time P fertilization imposed no impacts on NRE but on PRE in an age-specific way. Compared with N:Pgr, N:Psen may be more representative to show relative nutrient limitation in soils. Leaf nutrient resorption changed with leaf N:P which indicates the shift of relative nutrient limitation of soils. The P fertilization at 60 kg P2O5 ha?1 could guarantee the greatest PRE, equal NRE and higher dry biomass production in this region. Considering P resource finiteness and production cost, reduced amount or frequency of P fertilization is a desirable way of management for lucerne production in the Loess Plateau of China.