Many more trees could be planted without encroaching on crop land or urban areas
It can actually be better than this still. Cattle can be part of a solution to helping restore arid land where the soil has been destroyed by intensive farming and erosion. Healthy soil stores enormous amounts of biomass (aka carbon). Intensive farming has destroyed enormous amounts of land world-wide and turned it into desert, releasing lots of CO2 into the atmosphere.This is a reversible process and catlle is part of the solution: https://www.theguardian.com/environment/2011/jul/22/cows-cli...So, using large herds of cattle to refertilize bits of land that are currently not usable for agriculture would capture enormous amounts of carbon in the  soil, restore the water retention capability of arid land,  put a stop to large scale erosion of remaining soil, and restore it to productive land that may be used for growing food. Alternatively, once restored, you can sit back and watch the land reforest itself or use planned grazing to keep it as grassland. There's no actual need to manually plant trees; though it does probably speed up the process.Finally, using cattle to fix land produces lots of nice organic/free range meat in a sustainable way as a side effects. And yes, cow farts have a green house effect but it is offset by the captured CO2 in the restored soil. Healthy soil has lots of biomass.