Dampak Aplikasi Herbisida IPA Glifosat pada Pertanaman Padi Sawah Sistem TOT terhadap Tanah dan Tanaman Padi
Kesuma, S Dharma
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Weeds are among factors in decreasing paddy production, therefore should be controlled. The effects of weeds in decreasing paddy ranging from 6-87%. Weed control is generally carried out chemically by using herbicides. The use of herbicide with active subtance glyphosate is very common in agricultural areas in the world. This herbicide is used for post-emergence of weeds and it is non-selective. Using herbicides to control weeds is more efficient, inexpensive, and faster. In fact, it is more practical and cost-saving because there is no need to hire many laborers to remove unwanted plants. Application of no-tillage technology (TOT) using herbicides is considered far more effective and efficient. However, continuous use of herbicides can result in residues in the soil, plants and harvest results. The objective of this study was to analyze the influence of TOT and its combination with Glyphosate IPA herbicide on paddy production and its economic value, and the concentration of the residues of Glyphosate IPA herbicide in soil, straw and rice, and the maximum residue limit. This research was carried out in the paddy field with a plot size of 3 by 3 m as many as 5 treatment plots with 3 replications in order to total 15 experimental plots. The tillage was not performed on the experimental plots, except on the 3 plots with Gm treatment where conventional tillage (OTS) as farmer habits in the field. The spraying of herbicide was done once before paddy planting by using herbicide with active glyphosate IPA on perfect tillage treatment (Gm), G0 (without herbicide, control), with a glyphosate dose of 1.5 l ha-1 (G1), 3 l ha-1 (G2) and 4.5 l ha-1 (G3). Application of herbicides was carried out by spraying on treatment plots, except the control plot, with the right dose which had been determined. Seeds were evenly spread using paddy seeds of Mekongga variety. The seedbed was adapted to the common treatment carried out by farmers. The seedlings are ready for planting at aged 25 days. The planting method was carried out by placing the seedling in a digged-hole (ditugal). The planting on conventional tillage (OTS) was performed as usual, without ditugal. Fertilization was done twice using urea fertilizer as much as 200 kg ha-1, SP36 100 kg ha-1 and NPK Phonska 100 kg ha-1. Chemical fertilization was done by distributing it evenly on paddy plants. Weeding was carried out 2 times on the plots of Gm treatment, that is, when the paddy was 30 days and 60 days after seedling planting. Harvesting was done at the age of ± 4 months in which ready-to-harvest paddy was yellow and the branches already bent. Harvesting was done on the sample plots observed by covering each plot with tiles measuring 1 m by 1 m. Harvesting on the sample plots was carried out with caution. The paddy grain samples of each treatment were taken and weighed. The straw and soil samples of each treatment were taken from the tiled plots. Herbicide residue tests were carried out on the three types of samples: soil, straw and rice (milled paddy). The sampling of soil, straw and rice was conducted in 5 sample points. The determination of these sample points were based on 5 treatments. Each location consisted of 3 repeated points, and one composite was taken from each of these points. The soil samples of the rice fields as much as 500 grams were taken at a depth of 10-20 cm using a trowel, and then they were put in a plastic bag. The sampling of straw and rice harvest was done on location. The residual analysis was performed on the samples of soil, straw and rice by using a method of HPLC (high performance liquid chromatography). The research results showed that treatments Gm (OTS) and G1 (1.5 l ha-1) produced the highest grain production with the average production of dried mill paddy by 9,380 tons ha-1 and 7,280 tons ha-1 respectively. Gm treatment was more profitable with R / C ratio of 1.84 with a profit of Rp 13 714 000. However, the use of more laborers would be difficult to realize when applied to areas that lack manpower. G1 treatment is an alternative treatment that can be applied to areas that have less labor. Glyphosate contained in soil, straw and rice. Results of the analysis of glyphosate residue in the soil samples ranging 0.001-0.048 mg kg-1, straw 0.004-0.147 mg kg-1 and rice 0.009-0.272 mg kg-1. The highest glyphosate residue was found in rice samples of treatment G3 (4.5 l ha-1) as much as 0.272 mg kg-1, and the value was above the threshold of maximum residue set by the government (0.1 mg kg-1).