User:Lkbaird/sandbox

= No-till agriculture and soil erosion =

No till agriculture is a farming practice in which no form of tillage is used to control weeds, mix soil amendments into the soil, or prepare the ground for seeding. Crop residue or live vegetative cover is always left on the ground to protect it from erosive forces such as rain or wind. When this protective ground cover is removed, untilled fields are as susceptible to erosion as any other.

No-till practices are growing more popular as more and more farmers understand no-tillage farming causes no decrease in production while protecting the ground from the harmful effects of tillage, such as soil compaction, loss of organic matter, disruption of the soil's ecosystem, and perhaps most importantly, soil erosion.

A growing body of experimental evidence backs up the assumptive anti-erosive benefits of no-tillage systems.

Water erosion
The crop residue or live vegetation in no-till systems absorb the destructive force of rain better than bare soil. If a soil is left bare, the force of each raindrop splash can dislodge soil particles from the ground and result in soil loss. The crop residue also prevents and interrupts soil loss through surface runoff. When soil particles are dislodged by rain, water flow on the ground carries the soil particles away. The protective ground cover used in no-till agriculture interrupts water flow along the soil surface and can intercept any dislodged soil particles. This way the soil is captured and kept on site instead of washing downstream and causing sedimentation that could degrade streams.

Wind erosion
Crop residues are also thought to protect the soil from wind erosion by rooting the soil in place and absorbing some of the destructive velocity of the wind.

Experimental evidence
A number of experiments have backed up the belief that no-tillage systems can protect the soil from erosion.

In 1993, a study at the University of Kentucky concluded that no-till systems created significantly less soil loss and runoff volume than intensive or chisel plow tillage. In this study, no-till erosion was the only system to suffer no soil loss when simulated rainfall hit the dry soil. The total sediment loss in the no-till system after three simulated rainfall events was only 0.3 Mg ha-1, significantly lower than 3.3 Mg ha-1 for the chisel plow system and 15.5 Mg ha-1 in intensive tillage

Another study in 2003 indicated that no-till systems prevented soil loss in winter wheat/fallow crops in the spring and fall, when erosion is high, purely by the use of soil cover.

In 1984, an experiment by Lindstrom and Onstad concluded that soil erosion was greatest in no-tillage systems when the protective layer of crop residue was removed. However, the study also showed the no-till system had more runoff than a fall moldboard plow or a fall chisel plow system. The runoff problem was created by a host of undesirable physical parameters such as high penetrometer resistance, high bulk density, low saturated hydraulic conductivity, and low volume of macropores. This experiment only underlines the importance of ground cover in a no-tillage system. Without the protective qualities of a cover, no-till will not benefit the soil so greatly.