Phosphorus is a macronutrient which plays an important role in plant metabolism, growth, and development. However, in tropical acid soils, P fixation is high because of significant amounts of Al and Fe ions. Al and Fe ions can reduce diffusion of P into plant roots. Low absorption of P at initial growth of most plants causes stunting and slow growth of plant leaves. This process reduces photosynthesis. Chicken litter biochar (CLB) had been used on tropical acid soils to improve total P, available P, organic P, and inorganic fractions of P. Moreover, CLB is able to reduce exchangeable acidity, Fe, and Al ions in mineral acid soils because of the reactive surfaces of this organic amendment. However, there is dearth of information on the effects of the right combination of CLB and triple superphosphate (TSP) on the aforementioned soil chemical properties and crop productivity. To this end, the objectives of this study were to improve P: (i) Availability in a mineral acid soil and (ii) uptake, agronomic efficiency, and dry matter yield of Zea mays L. using the right amounts of TSP and CLB. Combinations of 75%, 50%, and 25% CLB (based on recommended 5 t ha⁻¹) and TSP (based on recommended P fertilization for maize) were evaluated in a pot study. Selected soil chemical properties, maize plants nutrient uptake, growth variables, and dry matter yield were determined using standard measures. Results showed that 25% and 50% biochar of 5 t ha⁻¹ with 75% TSP can increase soil P availability, recovery, agronomic use efficiency, and dry matter yield of maize plants. These optimum rates can also reduce P fixation by Al and Fe ions. Therefore, soil and maize productivity can be improved by using CLB (25% and 50% of 5 t ha⁻¹) and TSP (75% of conventional rate) to increase nutrients availability especially P.

Farming systems on peat soils are novel, considering the complexities of these organic soil. Since peat soils effectively capture greenhouse gases in their natural state, cultivating peat soils with annual or perennial crops such as pineapples necessitates the monitoring of nitrous oxide (N₂O) emissions, especially from cultivated peat lands, due to a lack of data on N₂O emissions. An on-farm experiment was carried out to determine the movement of N₂O in pineapple production on peat soil. Additionally, the experiment was carried out to determine if the peat soil temperature and the N₂O emissions were related. The chamber method was used to capture the N₂O fluxes daily (for dry and wet seasons) after which gas chromatography was used to determine N₂O followed by expressing the emission of this gas in t ha⁻¹ yr⁻¹. The movement of N₂O horizontally (832 t N₂O ha⁻¹ yr⁻¹) during the dry period was higher than in the wet period (599 t N₂O ha⁻¹ yr⁻¹) because of C and N substrate in the peat soil, in addition to the fertilizer used in fertilizing the pineapple plants. The vertical movement of N₂O (44 t N₂O ha⁻¹ yr⁻¹) was higher in the dry season relative to N₂O emission (38 t N₂O ha⁻¹ yr⁻¹) during the wet season because of nitrification and denitrification of N fertilizer. The peat soil temperature did not affect the direction (horizontal and vertical) of the N₂O emission, suggesting that these factors are not related. Therefore, it can be concluded that N₂O movement in peat soils under pineapple cultivation on peat lands occurs horizontally and vertically, regardless of season, and there is a need to ensure minimum tilling of the cultivated peat soils to prevent them from being an N₂O source instead of an N₂O sink.

The authors would like to make the following corrections to the published paper