Soil Organic Carbon Dynamics in Two Rice Cultivation Systems Compared to an Agroforestry Cultivation System

After changes in tillage on croplands, it is necessary to assess the effects on soil organic carbon (SOC) dynamics in order to identify if soil is a sink or emitter of carbon to the atmosphere. This study was conducted in two plots of rice cultivation, where tillage and water management changes occurred. A third plot of native forest with Cacao trees was used as reference soil (agroforestry). For SOC balance estimation, measurement of organic carbon (OC) inputs was determined from necromass, roots, microbial biomass, and urea applications. CO2 and CH4 emissions were also measured. Results showed that the change in the use of irrigation and tillage in rice cultivation did not cause significant differences in OC inputs to soil or in outputs due to carbon emissions. Further-more, it was found that both irrigation and tillage management systems in rice cultivation com-pared with agroforestry were management systems with a negative difference between OC inputs and outputs due to CO2 emissions associated with intense stimulation of crop root respiration and microbial activity. The comparison of SOC dynamics between the agroforestry system and rice cultivation systems showed that an agroforestry system is a carbon sink with a positive OC dynamic.

Heat transfer assessment of multi-tier chilling pipes for root zone cooling system under crop protection structure in the tropics

Root zone cooling technique has become an alternative cultivation method for temperate crops production in the tropics instead of cooling the aerial environment of the greenhouse. In this experiment, the root zone cooling system was incorporated with a multi-tier crop cultivation structure. This structure consisted of five tiers arranged in an A-shape design and was placed under an open rain shelter, thus, left it to undergo fluctuating environment temperature. There were five pillow polybags inserted with cocopeat and were placed on the structure. Each pillow polybag consisted of a single pipe that was buried inside the growth media located near the root zone area. This pipe that was connected to the chilled system acted as a cooling agent in controlling the growth media temperature. The objective of the study was to evaluate the Root Zone Cooling (RZC) system performance in distributing and controlling water-dissolved nutrient temperatures to meet crop-root requirement needs. From the experiment conducted, it was found that there was no significant difference between root zone temperature at different levels and lengths on multi-tier structure. The chilling pipes was able to distribute the temperatures to meet crop-root requirement needs along the multi-tier structure.

Impact of Tillage Systems Equipped with Row Cleaners on Some Selected Soil Physical Properties under Wheat Cropping

Availability of improved tillage and herbicides during the last decades has enhanced the acceptance of conservation tillage. The main constrain to this type of tillage, particularly, zero tillage is high level of crop residue, which reduces seeding quality, soil temperature, etc. Accordingly, a study was initiated by equipping row cleaners with no-till system under wheat cultivation. For this purpose, a field experiment was laid in a split-split plot design with three types of row cleaners, three sub-treatments of travelling speed, and two sub- sub treatments of tillage depth. The results indicated that the soil temperature was highly affected by percent of residue left. Measurement of penetration resistance indicated that hard pan was not a potential limiting factor for the crop root development. The soil water was increased by 8.83%, 15.33% and 12.54% under no-till without row cleaner (M1), no-till with narrow row cleaner (M2) and no-till with wide row cleaner (M3) respectively compared to that under conventional tillage (CT). The percentage of soil loss reduction under M1, M2 and M3 were 53.11%, 59.62% and 50.51% compared to that under CT. The water losses were also reduced by 46.19%, 48.65% and 46.86% under these treatments as compared with CT.