Résumé
This report is an internal document where all data recorded and they analysis are shown in detail. It will constitute a clear memory of the work done on maize agronomy in 1997. During the 1997 cropping season we moved one of the experimental fields from the Center of Carinagua to a farm named Matazul, where CIAT teams have been working for 10 years. This farm is located 40 km East of Puerto Lopez, Meta, adjacent to the main paved road. We prepared this change during the first months of 1997. Initial soil analysis and a laboratory test of the phosphorus fixation are reported. During this cycle I have conducted 5 agronomy trials at La Libertad and 3 at Matazul. L.A. Leon conducted 3 trials at Matazul. They all are reported here. Four trials (1 to 4) were planted at La Libertad and Matazul and two others (5, 6) were only planted at Matazul. These were: 1. Choice of one leguminous pasture to develop a system of permanent cover crop in which maize will be directly sown. 2. Comparative effect of tolerant versus non-tolerant varieties on soil fertility evolution. It was chosen to study a maize-soybean rotation, which is feasible in the area. 3. Interactions between maize tolerance and fertilization management for plant and root growth. 4. Need of micronutrients (Zn, B, Cu, Mn) application for maize growth. 5. Comparative effect of two nitrogen fertilizers: Nitromag vs. urea. 6. Interactions between phosphorus doses and types or doses of nitrogen fertilizers. The trial on sulfates or sulfur effect, initiated in 1996, was again conducted at La Libertad, to confirm the results and measure the residual effect of the amendments. At La Libertad trials were sown on April 29 and harvested on August 20, that is 15 days delayed from the recommended date of planting. Water was available in excess during all the cycle (page 5). Average trial yields varied from 2 to 3 t/ha, that is low when considering the inputs level. At Matazul, trial were only sown on May 21 and June 4, due to a rain coming delay and the need to wait one month after the dolomite application. Trials were harvested on September 22 and 26. They probably suffered some slight drought periods (page 5). Average yields varied from 1.5 to 2.5 t/ha, with more inputs than in La Libertad. (Résumé d'auteur)