graze only if adequate biomass in HRU set initial biomass before eating and trampling remove biomass eaten - assume evenly divided by biomass of plant later we can add preferences - by animal type or simply by n and p content remove biomass and organics from plant pools update remaining plant organic pools remove biomass trampled - assume evenly divided by biomass of plant remove biomass and organics from plant pools update remaining plant organic pools reset leaf area index and fraction of growing season assume lai doesn't start decreasing until 2,500 kg/ha at 1.0 lai per 1000 kg/ha plant loop
apply manure By Zhang for C/N cycling ===============================