In this study, the effect of different herbicide x pyroligenous acid mixtures on soil chemical and biological properties was evaluated in order to elucidate its potential impacts on nutrient availability and soil quality. The experiment was conducted under greenhouse conditions consisted of 100-fold diluted wood vinegar (100 WV), 50% BCB (Bentazone cyhalofop-butyl), 100% BCB, 50% BCB+100 WV, 50% BCB+250 WV and 50% BCB+500 WV applied against Echinochloa crusgalli. Ten days after herbicide application, the chemical properties were altered and the changes were influenced by the amount of WV dilutions. The soil pH was near neutral to slightly alkaline coupled with decreased electrical conductivity (EC). The total carbon, available phosphorous, exchangeable magnesium, exchangeable sodium, exchangeable calcium, exchangeable potassium and cation exchange capacity (CEC) were relatively lower compared to the control. Biolog TM assay showed that different treatments resulted to variable microbial activity, Shannon-Weaver index and richness of carbon utilization potential. Principal component analysis showed segregation of samples based on extracted principal components indicating variable carbon utilization potential due to different treatments combination. Correlation analysis between soil and microbial properties revealed that Principal Component 2 has negative correlation with pH and available P. On the other hand, Principal Component 3 was positively correlated with total C, exch. Ca, Mg, Na, and CEC (0.475, 0.490, 0.555, 0.489, and 0.517, respectively). Application of pyroligneous acid combined with herbicides resulted to changes in soil chemical and biological characteristics which may have unique implications on nutrient availability and overall soil quality.

To cite this paper: Seo, P.D., V.U. Ultra, M.R.U. Rubenecia and S.C. Lee, 2015. Influence of herbicides-pyroligneous acids mixtures on some soil properties, growth and grain quality of paddy rice. AbstractThe influence of herbicides-pyroligneous acids mixtures on soil chemical properties, growth and grain quality of paddy rice (Japonica cv. Ilpum) was evaluated in a field experiment. There were thirteen treatments including control (hand weeding), 100% and 50% application rate of three herbicides: Azimsulfuron+cafenstrole (AC), Mefenacet+pyrazosulfuron-ethyl (MPE) and Betazone+cyhalofop-butyl (BCB) and 6 combination of three types of herbicides at 50% recommended rate (RR) diluted with two types of pyroligneous acids: wood vinegar (WV) and rice vinegar (RV) at 500× dilutions; laid out in randomized complete block design with four replications. Results showed that lower application rate of herbicides combined with WV or RV gave a comparable effect in controlling weeds and on plant growth and chlorophyll content with their respective 100% RR application rate. Among different treatments, 50% AC + WV increased the number of spikelet per panicle and improved the grain quality compared to 100% AC. Treatment 50%MPE+RV decreased the spikelet number per panicle while 50% BCB+WV also reduced spikelet number per panicle, total protein content, and whole grain yield. After harvest, soil acidity, organic matter (OM), available P and EC increased due to treatments application. Overall, depending on the herbicide type, mixing 50% RR of herbicides with 500× of RV or WV dilutions can effectively control the weeds in paddy rice such as Echinochloa crusgalli, Monochoria vaginalis and Scirpus juncoides without suppressing the growth, and yield of rice with acceptable soil impacts that promotes environment health.

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