Land Suitability Evaluation for New Paddy Rice Field in Mukomuko District

This study aims to identify the physical, chemical characteristics of the soil and determine the suitability of rice fields for new openings in Mukomuko. This research was conducted from September to October 2019, which consisted of fieldwork and laboratory analysis. This research uses a survey method, soil sampling is carried out by a composite method consisting of 5 soil samples. Composite soil sampling technique based on land unit work maps produced from the map of soil types Mukomuko district scale of 1: 100.000. The results showed that all samples had the same dominant limiting factors namely P2O5, K2O, and Base Saturation. Land suitability for lowland rice plants in Mukomuko District Af.1.2.1 (S3nr) land area with an area of 42.68 ha, Af.1.2.2 (S3nr) land area with an area of 56.65 ha, land unit Tf.2.1 (S3nr) with an area of 60.15 ha, and land unit Tf.3.1 (S3nr) with an area of 89.30 ha.

A Study on the Applicability of HSPF Paddy-RCH for Calculating the Reduction of Agricultural Non-point Pollutants

Objectives:Non-point source pollution (NPS) reduction has been considered as the first priority in South Korea to achieve acceptable water quality. Among many NPS pollutions, agricultural NPS is one of the major NPS contributor due to its vast area. However, agricultural NPS characterization has not been successful because agricultural NPS has inconsistent water and mass balances, thus has lacking NPS reduction measures. This study assesses applicability of HSPF Paddy-RCH method to estimate agricultural NPS loads in paddy rice field.Methods:HSPF Paddy-RCH method was developed to simulate water and mass balance in paddy rice field(s). Applicability of the developed method was tested in Gyeseongcheon watershed in Nakdong River basin, South Korea. The study area was selected because there is no other major pollutant source except the paddy fields, but has simple drainage system. HSPF Paddy-RCH method was calibrated in control paddy field with conventional fertilizing condition and applied to two small scale paddy fields (89% and 76% fertilizing condition). The calibrated HSPF Paddy-RCH method was then tested in small watershed (subbasin) including small paddy fields applied earlier for applicability study of watershed scale.Results and Discussion:Calibrated HSPF Paddy-RCH method well represented observed flow rates (R2=0.825) and water-quality (BOD, T-N, T-P, relative differences [%diff]<7.52%). Water-quality parameters for the control paddy field showed slower decaying rate than river and stream. The calibrated HSPF Paddy-RCH well represented water and mass balance for the small scale paddy fields with varying fertilizing condition (R2>0.689 for flow rate, %diff<12.20% for water quality), as well as for the small scale watershed with large scale paddy fields (R2>0.693 for flow rate, %diff<19.29% for water quality) could promise.Conclusions:This applicability study results would suggest that HSPF Paddy-RCH method is a feasible tool to quantify agricultural NPS pollution and to develop reduction measured for paddy rice field.

Investigation of salt-tolerant rhizosphere bacteria from seawater-intruding paddy rice field in Vietnam

Salt‐tolerant plant growth‐promoting rhizobacteria (ST‐PGPR) are known as potential tools to improve rice salinity tolerance. In this study, we aimed to investigate the plant growth‐promoting rhizobacteria community richness of the paddy rice fields in Soc Trang and Ben Tre Provinces where were seriously affected by sea level rise. The salinity in the sampling sites ranged from 0.14‰ to 2.17‰ in November 2018, the rainy season. The microbial abundance of samples was evaluated by spreading the samples in tryptic soy agar (TSA) medium supplemented with various concentrations of NaCl. With the increase of salt concentration up to 10% NaCl, a total number of bacteria decreased for all the samples, ranging from 106 to 104 CFU/g, and bacterial colonies were not observed at 30% NaCl. Among a total of 48 salt-resisting bacteria isolated from the rice paddy field mud surrounding the rice root, 22 isolates were able to produce indole-3-acetic acid (IAA: phytohormone for the plant growth). Seventeen out of 48 isolates were able to grow in the medium without nitrogen or phosphor sources. Six isolates having high IAA producing activity, nitrogen fixation and phosphate solubilization were belonged to Bacillus (DT6, LT16, and LHT8), Halobacillus (DT8), Aeromonas (LHT1), and Klebsiella (LHT7) genera. All the sequences of the strains DT6, DT8, LT16, LHT1, LHT7, and LHT8 were registered in the GeneBank with the accession numbers MK335670, MK335671, MK335672, MK335673, MK335674, and MK335675, respectively.