<P> Soil conservation--The nature of dryland farming makes it particularly susceptible to erosion, especially wind erosion . Some techniques for conserving soil moisture (such as frequent tillage to kill weeds) are at odds with techniques for conserving topsoil . Since healthy topsoil is critical to sustainable dryland agriculture, its preservation is generally considered the most important long - term goal of a dryland farming operation . Erosion control techniques such as windbreaks, reduced tillage or no - till, spreading straw (or other mulch on particularly susceptible ground), and strip farming are used to minimize topsoil loss . </P> <P> Control of input costs--Dryland farming is practiced in regions inherently marginal for non-irrigated agriculture . Because of this, there is an increased risk of crop failure and poor yields which may occur in a dry year (regardless of money or effort expended). Dryland farmers must evaluate the potential yield of a crop constantly throughout the growing season and be prepared to decrease inputs to the crop such as fertilizer and weed control if it appears that it is likely to have a poor yield due to insufficient moisture . Conversely, in years when moisture is abundant, farmers may increase their input efforts and budget to maximize yields and to offset poor harvests . </P> <P> As an area of research and development, arid - zone agriculture, or desert agriculture, includes studies of how to increase the agricultural productivity of lands dominated by lack of freshwater, an abundance of heat and sunlight, and usually one or more of extreme winter cold, short rainy season, saline soil or water, strong dry winds, poor soil structure, over-grazing, limited technological development, poverty, political instability . </P> <P> The two basic approaches are: </P>

Farmers in central spain who practice dry farming answers