Jin-Hee Ryu

No-till Farming System: Research Direction and Outlook in Korea

No-till farming system has been extensively studied all over the world as the effective method for maintaining the soil fertility. The general advantages of this system have been well known for reducing the labor, fuel, machinery, and irrigation cost as well as for increasing the soil quality through soil aggregation, water infiltration, microbial population and etc. Recently, it becomes more popular with the increase of interest on sustainable agriculture, especially because of its higher carbon sequestration potential compared to conventional tillage. Crop residue management should be essentially included to look forward to achieving the positive effect on reduction of greenhouse gas. Nonetheless, there are also negative opinions on effect of no-till farming system. For example, some researchers reported that soil physical properties were not improved by no-till under certain soil and climatic conditions. This means no-till farming systems were strongly affected by the soil characters and climatic conditions. Therefore, the researches to meet the specific-regional characters are greatly needed in order for no-till farming system to successfully settle in Korea. The objective of the review article is to present the future direction and perspective on no-till farming system in Korea. For this purpose, we summarized the results of domestic and foreign researches about no-till farming system until now. Specifically, the chapter on foreign research consisted of four parts: positive and negative effects, the effect in paddy soil, and latest research direction (2012-2013) of no-till farming systems. Whereas, review for domestic researches was divided into two main parts: paddy and upland soils. In the final chapter, the priorities for the optimum conservation tillage in Korea were discussed and proposed through the previous researches.

Capillary Characteristics of Water and Cations in Multi-layered Reclaimed Soil with Macroporous Subsurface Layer Utilizing Coal Bottom Ash

Serious problems in reclaimed land agriculture are high soil salinity and poor vertical drainage, so desalinization in these soils is very difficult. Also, although desalinization is accomplished in reclaimed top soils, before long, soils are resalinized according to capillary rise of salts from the subsurface soils. To resolve these problems, multi-layered soil columns with subsurface layer of macroporous medium utilizing coal bottom ash (CBA) were constructed and the effects of blocked resalinization of these soils were investigated. In this experiment soil samples were collected from Munpo series (coarse-loamy, nonacid, mixed, mesic, typic Fluvaquents). The soil texture was silt loam and the EC was 33.9 dS m -1 . As for groundwater seawater was used and groundwater level of 1 cm from the bottom was maintained. The overall rate of capillary rise was 2.38 cm hr -1 in soil 60 cm column, 0.25 cm hr -1 in topsoil (30 cm) + CBA (5 cm) + subsurface soil (10 cm) column and 0.08 cm hr -1 in topsoil (30 cm) + CBA (10 cm) + subsurface soil (10 cm) column. In multi-layered soil columns with CBA 20, 30 cm layer, wetting front due to capillary rise could not be seen in top soil layer. After 70 days capillary rise experiment water soluble Na+ accumulated in top soil of soil columns with CBA 20, 30 cm was diminished by 92.8, 96.5% respectively in comparison with Na+ accumulated in top soil of soil 60 cm column because CBA layer cut off capillary rise of salts from the subsurface soil. From these results we could conclude that the macroporous layer utilizing CBA placed at subsurface layer cut off capillary rise of solutes from subsurface soil, resulting in lowered level of salinity in top soil and this method can be more effective in newly reclaimed saline soil.

Assessment of Sustainable Production on Paddy Field Treated with Green Manure Crops Using Sustainability Index

Assessment of sustainable production on a cropland can help to determine the most proper management practices. In this study, we evaluated the sustainable production on paddy field treated with green manure crops using sustainability index which based on nutrient index, microbiological index, and crop index related to nutrient-supplying capacity. Especially choosing appropriate indicators from a minimum data set (MDS) were used the principal components analysis (SI-2) as well as expert opinion (SI-1) usually used in sustainability index. Six treatments including the two tillage treatments and two green manure crops were investigated as follows; (i) moldrotary + rotary tillage without green manure crop (Con), with (ii) hairy vetch (Con-HV), and (iii) hairy vetch + green barely (Con-HV+GB), (iv) rotary tillage without green manure crop (Rot), with (ii) hairy vetch (Rot-HV), and (iii) hairy vetch + green barly (Rot-HV+GB). Con-HV and Rot-HV in SI-1 were maintained sustainability while Rot-HV and Rot-HV+GB in SI-2. Especially, treatments (Con and Rot) without green manure crops were more unsustainable than with green manure crops because of the low value of microbiological and crop index than with green manure crops. Meanwhile, sustainability indices and grain yield had the high correlation values (R²=0.756 and 0.928 in SI-1 and SI-2, respectively). These results meant that application of green manure crops such as hairy vetch could improve both yield and soil quality in paddy.

Effects of Partial Tillage Seeding of Hairy vetch on Green Manure Biomass and Rice Yield in Rice-based Cropping System

To investigate the effect of partial tillage seeding of hairy vetch on green manure biomass and rice yield, on-farm experiment was conducted at eco-friendly hairy vetch cultivation area located in Yesan-gun, Chungcheongnam-do. Seeding methods of hairy vetch consisted of partial tillage seeding (PTS) and broadcasting before rice harvesting (BBRH). Hairy vetch was incorporated into soil on May 18 and rice seedling was transplanted on May 26. The growths of hairy vetch before overwintering were investigated on November 11. Plant height of BBRH plot was longer than that of PTS plot, but somewhat larger number of seedling stand was found in PTS. Biomass and N production of hairy vetch were investigated on May 18. Results of the investigation showed no difference between two seeding methods. Although the seeding time was 21 days late in PTS, the biomass of hairy vetch and rice yield were equivalent to those of BBRH seeding, so we conclude that PTS could improve overwintering survival of hairy vetch in rice cropping system.

Effects of Straw Mulching on Soil Physicochemical Properties in Saemangeum Reclaimed Land

To identify the effects of straw mulching on soil physicochemical properties in reclaimed saline soil, field experiment was conducted for 3 years (2010~2012) in Saemangeum reclaimed land. Soil series of the experimental field was Munpo and soil texture was fine sandy loam. The experiment was conducted at a field with EC of 2.4 dS m -1 (field Ⅰ) and the other field with EC of 5.6 dS m -1 (field Ⅱ). Each experimental field was treated with rye straw incorporation, mulching with rye straw and control. In 2010 rye straw produced from other field was used for the experiment and in 2011~2012 rye straw cultivated at the same experimental field was used. After rye straw application, soybean was cultivated. After 3 years field experiment, by rye straw incorporation, soil salinity decreased from 2.4 dS m -1 to 0.6 dS m -1 at fieldⅠ but increased from 5.6 dS m -1 to 7.6 dS m -1 at field Ⅱ. By mulching with rye straw soil salinity decreased from 2.4 dS m -1 to 0.5 dS m -1 at field Ⅰ and also decreased from 5.6 dS m -1 to 0.5 dS m -1 at field Ⅱ. By rye straw incorporation and mulching soil organic matter increased from 2 g kg -1 to 4 g kg -1 . At field Ⅰ yields of soybean were similar between rye straw incorporation and mulching but at field Ⅱ yield of soybean increased apparently by mulching with rye straw compared to rye straw incorporation and control.

Effect of Legume Cover Crops and Nitrogen Fertilization Rates on Yield and Nitrogen Use Efficiency of Waxy Corn (Zea mays L.) in No-Tillage System

The adoption of legume cover crops in no-tillage system can contribute to improve soil fertility by providing several benefits, including reduction in soil erosion, suppression of weed growth and N supply to subsequent crops. We conducted a field study to investigate the effect of cover crops and nitrogen fertilization rates on yield and nitrogen use efficiency of waxy corn (Zea mays L.) in no-tillage upland field. Two legume cover crops, hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnuturn L.) were mechanically terminated with roller in early June. For each cover crop treatment, nitrogen (N) fertilizer was applied at three different rates (145, 72.5 and 0 kg N ha-1 ). The growth and yield characteristics of corn were significantly affected by the N fertilization rates in crimson clover plots, which suggest N mineralization from the cover crop residue was not sufficient. In contrast, N fertilization rates had no significant effect on growth and yield of corn in hairy vetch plots, indicating that the amount of N released from the cover crop is large enough to meet most of the N requirement of corn. However, the application of N fertilizer in hairy vetch cover plots resulted in slight increase of crop yield, though not statically significant, and high levels of N concentration in corn plant tissue possibly due to luxury consumption of N. Organic residues on the soil surface in hairy vetch cover plots had substantial amounts of N after harvest, ranging from 100 to 116 kg N ha -1 , which is presumably retained during winter season and released by microbial mineralization in subsequent year. The highest nitrogen yield efficiency was achieved in the plot with hairy vetch cover and no N fertilizer application, followed by the plot with hairy vetch cover and 72.5 kg N ha -1 fertilization rate. In conclusion, hairy vetch showed better performance in corn productivity as compared with crimson clover. In addition, it was concluded that the application of N fertilizer between 0 and 72.5 kg N ha -1 in combination with hairy vetch cover crop might be most efficient for corn yield under no-tillage system with climatic and soil characteristics similar to those of the experimental site.

Effect of Sesbania Incorporation as Nitrogen Source on Growth and Yield of Whole Crop Barley and Reduction of N Fertilizer in Saemangeum Reclaimed Tidal Land

It is known that the poor soil fertility of newly reclaimed saline soils is due to the lack of organic matter and available mineral nutrients for crop production. The effect of green manuring with Sesbania aculeata in combination with five rates of urea-N treatments (N0. N25, N50, N75, N100) on the productivity of a subsequent whole-crop barley and the fertility of the reclaimed saline soil in Saemangeum was evaluated in the field during 2013-2014 growing season. Sesbania was grown during summer season (June to October). The amount of Sesbania incorporated was 16.2 Mg ha -1 . Sesbania contributed to 393 kg N ha -1 to the soils when ploughed down and incorporated before whole-crop barley cultivated. The performances of whole-crop barley following sesbania incorporation were significantly affected by a combination of Sesbania manuring and different N rates. The N fertilizer equivalence without N fertilizer following Sesbania was 42.6% (63.9 kgN ha -1 ), compared with N100(150 kg N ha -1 ) in fallow soils. The whole-crop barley yield responded to N fertilizer rates in both sesbaniaamended and fallow soil. The yield response to nitrogen rates in fallow soil was linear (Y=0.0586X+3.3011, R 2 =0.9534), whereas that in sesbania-amended soils was quadratic (Y= -0.001X 2 +0.1322X+5.7143, R 2 =0.9576). The yield of whole-crop barley in sesbania-amended with increasing N rates was increased up to SN75 (115 kgN) 10.3 Mg ha -1 . Apparent N recovery (ANR) of whole-crop barely showed decreased with sesbania plus increasing rates of N fertilizer. Despite higher yield with sesbania manuring plus increasing N rates, the contributions of N from Sesbania with increasing N rates to whole-crop barley were decreased, whereas those from fertilizer increment due to excessively mineralized Nitrogen. Considering yield, ANR, N contribution from Sesbania and nitrogen fertilizer, the optimum N rate was N50 rate following sesbania incorporation.

Effect of Subsurface Drainage Systems on Soil Salinity at Saemangeum Reclaimed Tidal Land

Soil salinity is the most critical factor for crop production at reclaimed tidal saline soil. Subsurface drainage system is recognized as a powerful tool for the process of desalinization in saline soil. The objective of this study was to investigate the effects of subsurface drainage systems on soil salinity and corn development at Saemangeum reclaimed tidal saline soil. The field experiments were carried out between 2012 and 2014 at Saemangeum reclaimed tidal land, Buan, Korea. Subsurface drainage was installed with four treatments: 1) drain spacing of 5 m, 2) drain spacing 10 m, 3) double layer with drain spacing 5 m and 10 m, and 4) the control without any treatment. The levels of water table showed shorter periods above 60 cm levels with the deeper installation of subsurface drainage system. Water soluble cations were significantly greater than exchangeable forms and soluble Na contents, especially in surface layer, were greatly reduced with the installation of subsurface drainage system. Subsurface drainage system improved biomass yield of corn and withering rate. Thus, the biomass yield of corn was improved and the shoot growth was more affected by salinity than was the root growth. The efficiency of double layer was not significant compared with the drain spacing of 5 m. The economic return to growers at reclaimed tidal saline soil was the greatest by the subsurface drainage system with 5 m drain spacing. Our results demonstrated that the installation of subsurface drainage system with drain space of 5 m spacing would be a best management practice to control soil salinity and corn development at Saemangeum reclaimed tidal saline soil.

Metal-Urea-Montmorillonite Hybrid Incorporated with Citric Acid

Massive intercalation of urea into montmorillonite (MUCH) was recently proposed to enhance urea use efficiency through smart suppression of emission of NH3 and NOx. This study was to synthesize citrate-incorporated MUCH (Cit-MUCH) which can enhance suppression of NH₃ volatilization. The XRD pattern of Cit-MUCH was very similar to that of MUCH to indicate successful incorporation of citric acid into MUCH. Incorporation of citric acid was confirmed by the existence of COO- symmetric stretching vibration. During the initial 4 days after application, NH₃ volatilization from both bare and perilla-planted soils was much more suppressed by application of Cit-MUCH than MUCH. A peak volatilization rate decreased from 28.3 N mg m -2 h -1 of MUCH-broadcasted soil to 22.2 N mg m -2 h -1 of Cit-MUCH-broadcast soil. NH₃ volatilization was less in planted soil than bare soil for 72 hrs after application. These results showed that incorporation of citric acid led to increase in suppression of ammonia volatilization from urea-applied soils.

Changes of Hairy vetch Biomass by Different Seeding Methods and Rice Growth and Soil Physicochemical Properties by Its Incorporation in Paddy

Hairy vetch can fix nitrogen from the atmosphere as a leguminous cover crop. This research was carried out to determine optimum seeding method of hairy vetch and application effect in paddy. Field experiment was conducted at Sinheung series (fine loamy, mixed, nonacid, mesic family of Fluvaquentic Endoaquepts) from Sep. 2011 to Oct. 2012 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. Hairy vetch used in the study was ‘Cheongpyungbora’, developed by National Institute of Crop Science. Seeding methods of hairy vetch consisted of Broadcasting Before Rice Harvesting (BBRH), Partial Tillage Seeding (PTS), Minimum Tillage Seeding (MTS), No Tillage Seeding (NTS), and Drill Seeding (DS). Both MTS and NTS showed the highest biomass among the seeding methods. The rice yield of MTS and NTS significantly increased compared to conventional fertilization (CF). Also soil properties including organic matter and bulk density were improved by incorporation of hairy vetch. Therefore, we suggested that MTS and NTS could be used to produce hairy vetch and rice in paddy.