Soil nutrient loss through erosion: Impact of different cropping systems and soil amendments in Ghana

Abstract

Soil erosion is a multifactor threat to crop production and the environment. Most studies on soil erosion characterization have not focused on soil nutrient loss associated with erosion. The aim of this study was therefore to quantify the magnitude of nutrient loss through soil erosion under different cropping systems and amendments to inform agronomic practices in sub-Saharan Africa (SSA). A field experiment was carried out on runoff plots with different cropping systems (sole maize, sole cowpea, sole maize and maize intercropped with soybean) as main plots and soil amendments (biochar, NPK (Nitrogen +Phosphorus +Potassium) fertilizer, NPK + biochar and a control (no amendment)) constituting the subplots in a randomized complete block design. For each block, a bare plot was included to assess the efficiency of the different crop and soil management practices on soil erosion. The study was carried out in three consecutive cropping seasons in the semi-deciduous forest zone of Ghana. The bare plots had the highest amounts of nitrogen (N), phosphorus (P), and potassium (K) eroded: 33.88, 12.35 and 12.75 kg ha-1 respectively followed by the control plots with magnitude of 20.43, 8.42 and 7.87 kg ha-1 respectively for N, P and K. Sole maize had the highest amounts of nutrient loss: 19.71, 8.12 and 7.27 for N, P and K respectively compared to all the other cropping systems where the losses varied respectively from 12.38 to 17.12, 6.67 to 7.49 and 5.81 to 6.75 kg ha-1 The legume-based cropping systems under inorganic fertilizer and biochar management effectively reduced nutrient loss more than all other treatment combinations. The off-site effect of soil erosion expressed as enrichment ratio (ER) was higher for all plots, which received inorganic fertilizer inputs varying from 1.93 to 3.06 while the other treatments had ERs of 1.51 to 2.03. The ERs of fine soil particles were greater than 1 (ranging from 1.14 to 3.6) being relatively higher than that of coarse particles (sand) with values below 1 (ranging from 0.62 to 0.88). The least cumulative monetary value of nutrient loss (30.82 US$ ha-1) was observed under cowpea cropping system which received NPK + BC treatment. Soil erosion affected directly soil nutrient depletion through nutrient loss; however, integrated soil fertility management associated with legume-based cropping systems can be alternative options to reducing its effects on croplands in SSA.

Estimation of Soil Loss Tolerance in Olive Groves as an Indicator of Sustainability: The Case of the Estepa Region (Andalusia, Spain)

“…In the cases of moderate erosion, the inclusion of irrigation led to a decrease of 40% in the SPI, while in the olive groves with ecological management, there were increases of 136.84% and 153.33% with null and moderate erosion, respectively. As is well known, soil erosion decreases the soil's natural fertility, as it eliminates in a first stage the finest particles, clays, and organic matter, as well as nutrients, such as potassium, associated with these particles [25,77]. Soil nutrient loss through runoff and sediment is a major driver for soil fertility decline.…”

“…Soil nutrient loss through runoff and sediment is a major driver for soil fertility decline. In fact, erosion-based constraints associated with stressful climatic conditions define significantly the productivity of farming systems [77]. Furthermore, Qiu et al [72] suggest that potassium plays a critical role in ecosystem functioning and is a limiting factor in the recovery of vegetation, essential for soil cover.…”

Soil loss and run‐off characteristics under different soil amendments and cropping systems in the semi‐deciduous forest zone of Ghana

“…Though the use of biochar has received considerable research attention, its usage is still rather at the researcher level globally (Zhang et al, 2016), necessitating intervention of policymakers through appropriate subsidy programmes to enhance scaling up of its use for crop production in SSA. This will not only help reduce soil loss under cropping systems but will help make savings on fertilizer costs through reduction in fertility erosion in SSA (Bashagaluke, Logah, Opoku, Sarkodie-Addo, & Quansah, 2018).…”

A Comparative Analysis of Soil Loss Tolerance and Productivity of the Olive Groves in the Protected Designation of Origin (PDO) Areas Norte Alentejano (Portugal) and Estepa (Andalusia, Spain)

“…Finally, it is important to remark how olive groves in the PDO Norte Alentejano showed low-medium values of soil productivity, with the integrated olive grove plots without soil erosion being those with the highest productive potential. Such low productivity rates are due to the low soil potassium contents of the sampled plots and to the equally low percentages of organic matter and clays in the most eroded treatments, which are variables that can be considered key factors in agricultural yields [27,28,59,63,86].…”