Nitrogen dynamics and soil nitrate retention in a Coffea arabica—Eucalyptus deglupta agroforestry system in Southern Costa Rica

Abstract

Nitrogen fertilization is a key factor for coffee production but creates a risk of water contamination through nitrate (NO 3 À ) leaching in heavily fertilized plantations under high rainfall. The inclusion of fast growing timber trees in these coffee plantations may increase total biomass and reduce nutrient leaching. Potential controls of N loss were measured in an unshaded coffee (Coffea arabica L.) plot and in an adjacent coffee plot shaded with the timber species Eucalyptus deglupta Blume (110 trees ha À1 ), established on an Acrisol that received 180 kg N ha À1 as ammonium-nitrate and 2,700 mm yr À1 rainfall. Results of the one year study showed that these trees had little effect on the N budget although some N fluxes were modified. Soil N mineralization and nitrification rates in the 0-20 cm soil layer were similar in both systems (&280 kg N ha À1 yr À1 ). N export in coffee harvest (2002) was 34 and 25 kg N ha À1 yr À1 in unshaded and shaded coffee, and N accumulation in permanent biomass and litter was 25 and 45 kg N ha À1 yr À1 , respectively. The losses in surface runoff (&0.8 kg mineral N ha À1 yr À1 ) and N 2 O emissions (1.9 kg N ha À1 yr À1 ) were low in both cases. Lysimeters located at 60, 120, and 200 cm depths in shaded coffee, detected average concentrations of 12.9, 6.1 and 1.2 mg NO 3 À -N l À1 , respectively.Drainage was slightly reduced in the coffee-timber plantation. NO 3 À leaching at 200 cm depth was about 27 ± 10 and 16 ± 7 kg N ha À1 yr À1 in unshaded and shaded coffee, respectively. In both plots, very low NO 3 À concentrations in soil solution at 200 cm depth (and in groundwater) were apparently due to NO 3

Modelling the hydrological behaviour of a coffee agroforestry basin in Costa Rica

“…This is the smallest value reported in comparison to the other studies on coffee AF systems (Table 4). The closest value (38%, 956 mm in nine months) was measured by Harmand et al (2007), but it is about 1.5 times our ETR; while a maximum of 69% (985 mm yr −1 ) was reported by Jiménez (1986). It must be stressed that our study is the c The authors ignore whether this fraction is being stored in soil, or it became subsurface outflow downstream the gauging site.…”

“…The main novelties of the Hydro-SVAT model with respect to the model structure of Moussa et al (2007a,b) are the inclusion of a land cover reservoir to separate the intercepted rainfall from the combined throughfall/stemflow component, and the partition of non-saturated soil into two reservoirs, one with and one without roots of plants and trees. The first of these innovations intends to take into account the non-negligible interception loss in coffee AF systems, as reported by Jiménez (1986), Harmand et al (2007) and Siles (2007). The second new addition to the model is to better represent the water dynamics in the nonsaturated soil, given that only its upper layer will lose humidity by root extraction.…”

“…Some experimental basins are located in the tropics, like those in Brazil, Costa Rica, Guadeloupe and Panamá (Charlier et al, 2008;Fujieda et al, 1997;Genereux et al, 2005;Kinner and Stallard, 2004), but no coffee AF basins have been equipped so far. Some reports are available for coffee AF systems but at the plot level and for some particular fluxes such as throughfall and stemflow (Siles et al, 2010b), tree and coffee transpiration (Dauzat et al, 2001;van Kanten and Vaast, 2006), surface runoff (Harmand et al, 2007), energy balance and latent heat flux (Gutiérrez et al, 1994). To our knowledge, there is no comprehensive study of the water balance partitioning of coffee AF systems at the basin level, including the behaviour of the aquifer.…”

Performance of Coffea arabica F1 hybrids in agroforestry and full-sun cropping systems in comparison with American pure line cultivars

“…Furthermore, the coffee-growing area is one of the world hotspots for biodiversity. Coffee agro-forests, with shade trees interspersed amongst the coffee plants, are often the only habitat with remaining tree cover within these areas for migratory birds in the Mesoamerican biological corridor, as almost all forests have been removed at the elevations where coffee is grown (Harmand et al 2007;Jha and Dick 2008). These AS thus benefit international conservation initiatives.…”

“…Furthermore, rural households rely on fuelwood derived from trees in coffee agro-forests. Over the last 40 years, coffee cultivation intensification has led to the loss of more than 50% of the tree cover (Harmand et al 2007). This coffee intensification has also resulted in loss of landscape connectivity and extensive loss of biodiversity in many coffee-growing zones, and probably an increase in agrochemical pollution of rivers and aquifers (Babbar and Zak 1995).…”