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What's a Mac~opore? .... .. C~ (;) CJl Macropores are op/inings or channels that develop patural/y in soil if ff is not disturbed by tillage or compaction. They promote rapid infiltration of water and improve drainage and aeration in the root zone, Macropores develop readily-under no-IiI/cropping sysle17Jf and may help reduce runoff. Bul theY; also may provide an efficient path for contaminants to reach ground waler. , , .. Nitrate and pesticides may be carried to ground water ,IW m!lcro- pores even In relatively Impermeable solis: Oakwood Lak.s, South Dakota: Conservation tillage is the BMP used to minimize pollutants entering surface waterways. For similar rainfall events, no-till plots,oon- sistently allow water to penetrate deeper and faster compared to mold- board plowing. This difference is thought to be caused by the natural formation of macropores, which mold-board plowing disrupts. Agricultural chemicals may also penetrate more under no-till, but the increase has not been statistically significant. III Terracing, designed to reduce ,sediment losses In surface runoff, may adversely affect ground-water quality: the ConestoQa Head- waters project In Pennsyfvania demonstrated a potential for conflict when trying to restore the quality of ground water and surface water at the same time. Ground-water nitrate data collected during non-recharge periods' at a 23-acre field site where terracing and nutrient management practices were implemented indicated that terraces may have .increased nitrate concentrations. Median nitrate levels rose by 1 to 4 mglL for four of the six ground-water sampling sites after the BMPs were in place, At one other site the median nitrate level decreased by nearly 2 mglL, while at the sixth site no change was measured. Although further analyses are needed, these results certainly' demonstrate that the effects on the entire water system must be con- sidered when designing management systems. ~1 III Other fll1dlngs: The findings described regarding the effectiveness of BMPs are representative of the best-documented results from the flCWP, but there are many other findings to be shared by each project and by the Water Duality Evaluation Project at North Carolina State University. For example, nutrient and pesticide management can be critical to the long- term success of both the producer and those who are'addressing water quality problems. Similarly, water management and some form of conser- vation tillage system are usually needed to address sedimenta,tion problems. While findings such as these are based upon experience rather than on specific water quality data, they are important. Voluntary + Cost-sharing: Does It Work? II Cost-sharing helps, but cannot guarantee participation: Attractive cost-sharing and technical assistance incentives generally increase farmer participation. The RCWP cost-share rate of 75 percent (a maximum of $50,000 per farmer) was attractive in most projects, but not in all. For ex- ample, cost-sharing at a 90 percent level failed in Minnesota, largely be- cause farmers were asked to build expensive structural BMPscduring a depressed economic time. Lower-cost manure management might have been more successful in gaining participants. Pooling cost-share monies among several cooperators was used suc- cessfully by the Nebraska project to fund construction of a water control structure to prevent erosion and improve the timing of irrigation flows. The project benefited many farmers and increased their interest in the i'lCWP. No matter what the cost-sharing rate is, however, the BMP must beac- ceptable to the user or it won't work. The landowner and the farm operator must be willing to adapt the BMP to their farm's unique situation, and to 4