The practice of social participation in the formulation of public policies based on the diagnosis of plant cover in the town of Rio das Ostras

Abstract

Erosive processes are the main cause of soil and spring degradation (productivity loss, drought, salinization and eutrofization). This study took place from November 2007 to May 2008, encompassing the period of natural rainfalls, and using a specific methodology to integrate empirical studies of the water, soil, Al, organic components (Corg., OM) and total nutrient (B, Ca, Cu, Fe, K, Mg, Mn, N, Na, P, S and Zn) loss survey. The study was carried by means of three experimental parcels (P1, P2, P3) made of a 22 x 3.5 m pinewood board set up in favor of the slope on the coffee plantation (Coffea arabica L.) in the Panorama II farm in the Paraiba do Sul microbasin, Varre-Sai, RJ, aiming at the adoption of management and preservation practices in the region. The parcels were coupled to 200 L gallon collectors, isolating water and soil losses, through biddin, for quantification of the obtained losses on each erosive rain event (>10 mm), according to the USLE methodology. Simultaneously, water samples were collected at two locations on the water course (high course far from the crops, AC; and low course near the coffee section, BC) for the physical-chemical characterization, in order to identify possible cultivation influence. From January through April 2008, 60% of the rainfalls were considered erosive, and only 36% of these were responsible for generating soil loss in the coffee cultivation. Considering only daily erosive rain events, only 1% was drained from a total precipitation of 515mm. The average water loss during the period was 0.24 mm with a time interval of 0.03 to 0.96 mm. The soil loss average was 3.99 kg.ha-1 with a time interval of 0.69 to 9.77 kg.ha-1. The sediment pull potential (SAP) was 0,01 Mg.ha-1.mm-1; such a low value shows that dense coffee cultivation (1.75 x 1 m), as it occurs in the observed section, acts as an important physical-chemical barrier to reduce the torrent speed, to decrease nutrient and sediment losses. Statistical tests identified a significant positive correlation between precipitation, flow and nutrient loss in the parcels. A comparison between the smaller number of soil loss (n=9) and water loss events (n=25) shows that the largest nutrients losses were resulted from the flow, except for Zn and Mn. The nutrient losses accumulated during the period mostly associated with the flow were: 50.2 g.ha-1 for NT; 5.11 g.ha-1 for Ca; 4.77 g.ha-1 for the K; and for micronutrient Fe with 0.35 g.ha-1. Nutrient concentrations in the drained water and soil loss showed the same behavior, being larger at the beginning of the observation period and after external support by manuring on January 30, 2008 due to greater manure availability on the soil, also following the highest precipitations and flow. The small differences in the flow, soil and nutrient losses among experimental parcels were possibly due to the heterogeneous disposition of litter on the terrain by wind or water effects; to the different application of manure and fertilizers on the coffee section coffee along the year; and to the distinct interaction between water and rain, coffee cultivation and soil. However, the statistical test identified significant difference just for the loss of K, in P2 regarding other two. The study identified a lineal correlation input Corg and soil losses, which indicates that the process of water erosion was selective, and the organic fraction was first, preferably when removed from the soil. No identification was found of the influence of the coffee cultivation on the water course quality, possibly due to the 100 m distance and the reduced losses observed. However, during the observation period Ca, Fe and NT increments were identified along the temporal series, which may represent participation of material loss in neighboring farming areas. In order to associate local community’s perception of the water erosion by socializing results obtained in the coffee cultivation, two meetings were scheduled (February 23 and May 2, 2008), following a methodological adaptation of the Fast Participative Diagnosis (PRD), allowing for the local community’s awareness of the need to adopt management and preservation practices. The experimental practice related to popular participation enabled the present study to elaborate intervention proposals on the coffee cultivation, such as: need for litter maintenance on the soil during the cultivation; crop rotation within larger coffee grounds (vegetables); gradual incorporation of organic agriculture in the conventional practice (chicken earthworm or earthworm humus in controlled dosages); reduction of chemical products in the coffee section; planned usage of manuring and fertilizers applications associated to weather variation (rainfall occurrences); maintenance of dense coffee cultivation (1.75 x 1 m), and adaptation of terraces to local characteristics. Regarding this aspect, Terrace 3.0 software was used, showing two possible scenarios for their installation in a pre-established culture. A suggestion was given concerning the formation of the built-in level terrace (narrow base) adapting the relation terrain-coffee particularities. Thus, guidelines were presented aiming at aggregating value to the traditional culture and reducing impact on the natural resources of the Paraiba do Sul watershed in Varre-Sai. Maintenance of these natural resources depends on the application of preservation and management techniques which promote a better productive interaction in the water-soil-plant interface.