Changes in Soil Physical and Chemical Properties in Long Term Improved Natural and Traditional Agroforestry Management Systems of Cacao Genotypes in Peruvian Amazon

Abstract

Growing cacao (Theobroma cacao L.) in an agroforestry system generates a productive use of the land, preserves the best conditions for physical, chemical and biological properties of tropical soils, and plays an important role in improving cacao production and fertility of degraded tropical soils. The aim of this study was to evaluate the impact of two long term agroforestry systems of cacao management on soil physical and chemical properties in an area originally inhabited by 30 years old native secondary forest (SF). The two agroforestry systems adapted were: improved natural agroforestry system (INAS) where trees without economic value were selectively removed to provide 50% shade and improved traditional agroforestry system (ITAS) where all native trees were cut and burnt in the location. For evaluation of the changes of soil physical and chemical properties with time due to the imposed cacao management systems, plots of 10 cacao genotypes (ICS95, UF613, CCN51, ICT1112, ICT1026, ICT2162, ICT2171, ICT2142, H35, U30) and one plot with a spontaneous hybrid were selected. Soil samples were taken at 0-20, 20-40 and 40-60 cm depths before the installation of the management systems (2004), and then followed at two years intervals. Bulk density, porosity, field capacity and wilting point varied significantly during the years of assessment in the different soil depths and under the systems assessed. Soil pH, CEC, exchangeable Mg and sum of the bases were higher in the INAS than the ITAS. In both systems, SOM, Ext. P, K and Fe, exch. K, Mg and Al+H decreased with years of cultivation; these changes were more evident in the 0-20 cm soil depth. Overall improvement of SOM and soil nutrient status was much higher in the ITAS than INAS. The levels of physical and chemical properties of soil under cacao genotypes showed a marked difference in both systems.

Soil chemical and physical characteristics as a base for achieving sustainable forest land use in RPH Watugudel, KPH Ngawi, Jawa Timur

“…The porosity also varies from 46.30 % (at settlement area) to 60.80 % (at the rice field area). This finding supports the earlier work by [11] who reported inverse relationship between bulk density and porosity of the soil.…”

Recovering degraded lands in the Peruvian Amazon by cover crops and sustainable agroforestry systems

“…Some high and low input technologies in long term trials have been tested in the humid acid tropical soil of Yurimaguas, Peru and one of the main options was the agroforestry systems (Palm, 1995;Alegre, 2015). The introduction of perennial cropping systems with coffee or cacao managed with cover crops also offers an alternative to recover degraded land in the Amazon (Puertas et al, 2008;Arévalo-Gardini et al, 2016). The potential of trees and cover crops to contribute to the maintenance and rehabilitation of the soil's physical characteristics such as better bulk density, mechanical resistance and soil aggregation has been well established, including an improvement on productivity (Alegre and Rao, 1996;Rao et al, 1998;Alegre et al, 2005).…”

Changes in soil properties in a low-quality broadleaf mixed forest after cutting strip reforms in a 9-year period in Northeastern China

“…(Guan et al, 2018;Gao et al, 2013). Recently, many researchers have attached great importance to understanding the impacts (Arevalo-Gardini et al, 2015;Pang et al, 2011). Some studies have shown that harvesting not only destroys the physical properties of the soil, but also affects the chemical properties, especially the soil water holding capacity and soil porosity.…”