Summary
This site had been studied from 2002 until 2007. The location comprises 4 plots of 1 000 m2 (50*20 m). The fields are located on a very moderate slope (5%) on the size of a convex long hill on the piedmont of the wall of a volcanic caldera of 13M years old. Deep gullies are present on the feet of the plots. SWCs tested include improvement of fertility, increasing of permeability, reducing of soil erosion, mulching, increase of field production for man as well for animal. Plots are under 4 different agronomical treatments based on the traditional crop association of maize+beans+zuquini: Fallow, traditional crop, zero tillage+crop residues, crop with improved fertility (chemical + crop residus). In year 4 and 5 the improved fertility treatment had been reemplaced by barley crop. Ploughing direction is normal. Plots are delimitated by small earth wall and a H-flume downstream conduce runoff and sediments eroded to "balance-tanks" of 2 000 l capacity. In case of higher runoff volume, a nearly 2% of water quantity is retain in a second tank. Water with sediments was sampled after every event (means nearly every day during rainy season). Water was analyzed (N, P, K, C) as well as sediments if thir quantity allow it (rare cases). On fields, soil water contents (Watermark tensiometers) at 5, 15, 30, 50 and 80 cm deep was followed dayly, roughnes (rugosimeter during year 1 and 2 then chain) ) and soil cover (photo+GIS) after every heavy rain. CO2 respiration was followed 1 time /month from 2005 to 2007. In year 5, samples to measure aggregate stability had been done. Field production was measured too. Meteo variables are measured every 30 mn (except rain every seconds during rain event) in place.
