Improving the physical conditions of the paddy fields with irrigated paddy rice and upland crop rotation by no-till and no-puddled rice culture

Transcription

1 Symposium no. 22 Paper no Presentation: poster Improving the physical conditions of the paddy fields with irrigated paddy rice and upland crop rotation by no-till and no-puddled rice culture OTA Takeshi, MURAKAMI Shou, FUJII Yoshikazu and KOBAYASHI Hitomi Akita Agricultural Experiment Station, Oogata Experimental Farm,Higashi 1-1, Oogata, Akita, , Japan Abstract In recent years, Japanese agriculture has been facing serious problems including overproduction of rice. Poorly drained paddy fields in the heavy soil area also have been often converted to upland fields. In these upland fields, however, productivity are lower due to many limitations such as wet injury. Recently, no-till and no-puddled rice culture have developed using rice seedlings grown by the single application of controlled availability fertilizer to nursery boxes and the efficient transplanters. In irrigation period, the surface horizons of these rice culture are more oxidized condition compared with those of the conventional puddled rice culture. The authors tried to improve physical conditions of the paddy fields with irrigated paddy rice and upland crop rotation by the no-till and no-puddled rice culture. We converted three drained paddy fields for upland crop cultivation to no-till, nopuddled and conventional puddled (control) rice culture fields. Three years after, we converted these fields to upland fields again and vegetable soybeans were cultivated. We studied the changes in soil morphologies, soil properties, growth and yield of vegetable soybeans. The no-till and no-puddled rice culture have preserved upland soil properties such as soil structure and oxidized condition those developed when the fields were used as the drained paddy fields for upland crop cultivation. When the fields were used again for upland crop cultivation, oxidized condition and soil structure were developed in the plow pans of the fields after the no-till and no-puddled rice culture. In these fields, the roots of vegetable soybeans could penetrate in those plow pans easily and could uptake water and nutrients from subsoils. In the contrast, the plow pan of the field after the conventional puddled rice culture was reduced condition, no structure and few root of vegetable soybeans could penetrate. The no-till and no-puddled rice culture, before conversion into upland fields, appeared to be effective in increasing growth and yield of vegetable soybeans. Keywords: no-till rice culture, no-puddled rice culture, poorly drained paddy fields, paddy fields with irrigated paddy rice and upland crop rotation Introduction In recent years, Japanese agriculture has been facing serious problems including overproduction of rice. Poorly drained paddy fields in the heavy soil area also have been often converted to upland fields. These converted upland fields in the heavy, clayey soil

2 are usually have reduced and compacted plow pans, and very poorly drained conditions. After heavy rain, we often observe water logging in these fields. In particular, pulverizing the soil to obtain a good seedbed is very difficult for such clayey paddy fields. In these fields, productivity are lower due to many limitations such as wet injury and few root can penetrate the plow pans. Recently, no-till and no-puddled rice culture have developed using rice seedlings grown by the single application of controlled availability fertilizer to nursery boxes and the efficient transplanters 1). No-till rice culture which eliminates conventional plowing and puddling, and no-puddled rice culture eliminate puddling are expected to increase labor efficiency. A new type of controlled availability fertilizers, where nitrogen release is delayed for a specified number of days and then increases rapidly after the lag period, has been developed in Japan. With the development of efficient no-till transplanters, farmers in Oogata village are now beginning the no-till and no-puddled rice culture in large-scale fields. In irrigation period, the surface layers of the no-till rice culture are more oxidized condition compared with those of the conventional puddled rice fields. Because, the surface layers of the no-till rice culture are not incorporated with rice straws, and have many pores i.e. root traces. The surface layers of the no-puddled rice culture are also oxidized condition due to many pores. The authors tried to improve physical and drainage conditions of the paddy fields with irrigated paddy rice and upland crop rotation by the no-till and no-puddled rice culture. Materials and Methods Experimental site and soils The experiments were conducted in the paddy fields at Akita Agricultural Experiment Station, Oogata Experimental Farm in Akita, Japan. The soils are finetextured Mottled Gley Lowland soils (WRB: Eutric Fulvisols). Clay contents are about 50% and smectite is the major mineralogical component. Carbon and nitrogen contents of the upper part of the soils ranged from 18 to 28 and from 1.8 to 2.3 g kg -1, respectively. Values of CEC and ph(h 2 O) ranged from 39 to 49 cmol(+) kg -1 and from 7.0 to 7.4, respectively. The mean annual precipitation and temperature are 1,790 mm and 10.8 degree Celsius, respectively. Experimental design and analytical methods Table 1 shows the design of the experiment consisted of three plots 0.1 ha each. We converted three drained paddy fields for upland crop cultivation to no-till (No-till plot), no-puddled (No-puddled plot) and conventional puddled (Puddled plot as control) rice culture fields. In the No-till plot, the first year of conversion into the rice field was conducted puddling due to leveling the field. Three years after, we converted these fields to upland fields again and vegetable soybeans were cultivated. We studied the changes in soil morphologies, soil properties, growth and yield of vegetable soybeans. Morphological features such as soil structure and dipyridyl reaction (active ferrous iron test) were investigated every after the rice and vegetable soybean harvest. In this paper, we defined the gley horizons as the horizons that have color value bluer than 10Y and dipyridyl reaction are stronger than immediately but faintly (+)

3 Table 1 The design of the experiment. The disturbed and undisturbed soil samples were collected every after the harvest from each soil horizon. The undisturbed soil samples collected using cores (100 ml volume, 5 cm diameter and height) were measured-6.3 kpa water content by pressure plate method. The disturbed fresh soil samples were used to measure plastic limit. Uplandization index (plastic limit/-6.3 kpa water content) were used to quantify the changes of the soil microstructure and water holding capacity caused by conversion. This index values increase when a field is converted to upland conditions i.e. dry and oxidized conditions, and decrease when the field restored to paddy field conditions i.e. wet and reduced conditions. In 1999, before vegetable soybeans were seeded, pulverization ratios (ratio of soil clods smaller than 2 cm diameter) and water contents of the soils were measured twice successively after rotary and paddy-harrow type tillage. We seeded vegetable soybeans with chemical fertilizer 30 kg N ha -1. We measured the height of main stem and the weight of yield and root of vegetable soybeans. Results and Discussion Changes in soil morphologies and physical properties Figure 1 shows the time course of the changes in soil morphologies. Gley horizon. In the first year, the fields converted from upland to paddy, the depths of the gley horizons in the No-till and Puddled plots were elevated to 31 and 15 cm, respectively, because of puddling. The depth of the gley horizon in the No-puddled plot was lower than 50 cm. In the second and third years after conversion into rice culture, the depths of the gley horizons in the No-till plot were about 30 cm and lower than those of the Nopuddled and Puddled plots. Those of the No-puddled and Puddled plots came up to plow pan (second layer) and plow layer, respectively. After conversion into upland fields again, the depths of the gley horizons in the Notill and No-puddles plots came down to lower than 30 cm. The plow pan of the Puddled plot, however, was still reduced condition after the harvest of vegetable soybeans. Soil structure In the third year after conversion into rice fields, soil structure were remained in the plow pan of the No-till plot. Those of the No-puddled and Puddled plots were massive (no structure)

4 cm 0 P O No-tillplot 2.5Y3/2 Q O R O S O T O 5Y4/2 7.5GY4/1 7.5GY4/1 5Y4/2 7.5GY4/1 2.5Y4/2(50%) (50%) 5GY4/1 V.5GY4/1 V.5GY4/1 2.(50%) 5Y4/2(50%) m oderate 5GY4/1 prism atic 5GY4/1 cm 0 P O Q O R O S O T O No-puddled pot 10YR3/3 10YR4/2 2.5Y5/2 b l 7.5Y5/1 prism atic V.5GY3/1 7.5GY4/1(50%) 10YR4/4(50%) 7.5GY4/1 V.5GY3/1 2.5GY4/1(70%) 5Y4/2(30%) V.5GY4/1 2.5Y4/2 5Y4/2(75%) (25%) (50%) 10YR4/4(50%) 2.5GY4/1 2.5GY4/1 cm 0 P O Q O R O S O T O Puddled plot 10G 3/1(40%) 10YR3/2(60%) 5G Y4/1 7.5G Y4/1 10G 4/1(60%) 10YR4/4(40%) 5G Y3/1 7.5G Y4/1 2.5G Y4/1 5G Y4/1 5G Y3/1 7.5G Y4/1 2.5G Y4/1 2.5G Y4/1 2.5G Y4/1(50%) 2.5Y3/3(50%) 7.5G Y4/1 5Y4/2 5G Y4/1 2.5G Y4/1 One yearafter paddy Two years afterpaddy Three years afterpaddy Converted upland Mottle Shel Gley layer Figure 1 Time course of the changes in soil morphologies. Dotted lines show the upper boundaries of the gley horizons. After converted to upland fields, moderate and soil structure were developed in the plow pans of the No-till and No-puddles plots. The plow pan of the Puddled plot, however, had been massive

5 Dipyridyl reaction of the plow pan In the No-till plot, dipyridyl reaction were more oxidized condition than the Nopuddled and Puddled plots in the second and third years after conversion into rice fields. After changed to upland fields again, the No-till plot didn t show a positive ferrous iron reaction means dry oxidized condition. Whereas, the No-puddled and Puddled plots showed immediately but faintly, and immediately and prominently positive ferrous iron reaction, respectively (Figure 2). Figure 2 Time coruse of the changes in dipyridyl reaction (active ferrous iron test). -After a litter while, do not show a positive ferrous iron reaction. ±After a litter while, faintly show a positive ferrous iron reaction. +Immediately but faintly show a positive ferrous iron reaction. ++Immediately and distinctly show a positive ferrous iron reaction. +++Immediately and prominently show a positive ferrous iron reactive. Uplandization index of the plow layer This index values of the No-till plot remained constant and rather large in the second and third years after conversion into rice field. The values of the No-puddled plot were decreased significantly in the second years after converted to rice field. The values of the Puddled plot decreased gradually with years after conversion (Table 2). Table 2 Time course of the change in uplandization index

6 Growth and yield of vegetable soybeans Pulverization ratios and water contents The first measurement of the pulverization ratios performed on 27 th April after short dry spell. The water content of the No-till plot was smaller and the pulverization ratio was higher than those of the No-puddled and Puddled plots. At the second measurement of the pulverization ratios on 17 th May, the water contents of the No-till and No-puddled plots were rather smaller and the ratios were a little higher than those of the Puddled plot. These attributed to the oxidized condition and development of soil structure in the No-till and No-puddled plots (Table 3). Table 3 Pulverization ratio and water contents of the soils after tillage in the fields converted from paddy rice to upland in Pulverization ratio=rario of soil colds smaller tha 2 cm diameter. 4/27 Measured after rotary type tillage. 5/17 Measured after paddy-hallow type tillage on 5/14 and 5/17. Weight of root Weight of the roots in the No-till, No-puddled and Puddled plots were 73, 54 and 44 g/stem, respectively. In the No-till and No-puddled plots, the roots of vegetable soybeans could well penetrate in the plow pans (second layers) because those had oxidized condition and soil structure. In the Puddled plot, however, few roots could penetrate in the plow pan which was reduced condition and no structure (Figure 3). Main stem height and yield The early stage of vegetable soybeans, there were no difference in the height of main stem among the three plots. From the end of June, the height of main stems in the No-till and No-puddled plots were increased more rapidly than that in the Puddled plot. This may caused by deeper penetration of the roots in the No-till and No-puddled plots. During the end of June to early August, vegetable soybeans need much water and nutrients. In this period, however, rain precipitation was scarce. The vegetable soybeans of the No-till and No-puddled plots probably could uptake sufficient amount of water and nutrients from the subsoils in this period (Figure 4). The yield of vegetable soybeans in the No-till and No-puddled plots increased 20% than that in the Puddled plot (Figure 3)

7 Figure 3 Yield and weight of roots of soybeans in the fields converted from No-till, No-puddled and Puddled rice culture. Vertical bars represent SD (n=20). Figure 4 Main stem height of vegetable soybeans in the fields converted from Notill,No-puddled and Puddled rice culture. Vertical bars represent SD (n=20)

8 Conclusion The no-till and no-puddled rice culture have preserved upland soil properties such as soil structure and oxidized condition those developed when the fields used as the drained paddy fields for upland crop cultivation. When the fields were used again for upland crop cultivation, oxidized condition and soil structure were developed in the plow pans of the fields after no-till and no-puddled rice culture. In these fields, the roots of vegetable soybeans could penetrate in those plow pans easily and could uptake water and nutrients from subsoils. In the contrast, the plow pan of the field after conventional puddled rice culture were reduced condition, no structure and few root of vegetable soybeans could penetrate. The no-till and no-puddled rice culture before conversion into upland fields appeared to be effective in increasing growth and yield of vegetable soybeans. Reference Kaneta, Y Single application of controlled availability fertilizer to nursery boxes in non-tillage rice culture. Japan Agricultural Research Quarterly 29: