Key words: long-term soil monitoring, database, soil property, fertilizer management, organic matter, Japan
In Japan, long-term soil monitoring field expe-riments with different plant nutrition management practices are conducted in all provincial agricultural experiment stations under the Project of National Soil Conservation. Systematic long-term soil monitoring started in 1975. Kusaba and Ishioka (2008) established a database from the results of about 20 years of continuous long-term soil monitoring. This database contains the amount of applied chemical fertilizer and organic matter (rice straw, animal manure compost, and rice straw compost), crop yields, and soil properties, and has a data retrieval function.
Long-term soil monitoring field experiments with different fertilizer management schemes are useful for analyzing the effects of fertilizer management on crop yields and soil properties, especially for sustainability assessment. In Japan, many studies have been reported on the effects of long-term fertilizer management on crop yields and soil properties in each prefecture (Maeda 1974, Tatsumi et al. 1985, Kamimura et al. 1994). However, nationwide analyses of the effects of long-term fertilizer management are scarce. Uwasawa (1991) studied nationwide long-term soil monitoring data during 1976-1983 and reported that organic matter application enhanced crop yield and improved soil properties in both paddy and upland fields. Yamashita (1967) evaluated the effects of prolonged (10-33 years) application of farmyard manure in nine paddy fields and found out that manure application improved the soil's chemical and physical properties such as total carbon, CEC, and water-stable aggregates. Reeves
(1997) reviewed worldwide long-term field studies and showed the benefits of organic matter and adequate fertilizer application for maintaining crop productivity by increasing organic matter inputs to the soil.
This study aimed to introduce the newly established long-term soil monitoring database (Kusaba and Ishioka 2008) and use this database to investigate how fertilizer management affects crop yields and soil properties. Using this database, nationwide changes in soil properties and crop yields of Japanese paddy fields were examined.
General Information on Long-Term Soil Monitoring Database
Aims of Long-Term Soil Monitoring Field Experiments
Since 1975, systematic long-term soil monitoring field experiments have been conducted throughout Japan by the Ministry of Agriculture, Forestry and Fisheries (MAFF) under the Project of National Soil Conservation. The aim of this project was to trace the changes in crop yields and soil properties associated with successive crop cultivations with different fertilizer management schemes. All prefectures throughout Japan have been participating in this survey.
Outline of Long-Term Soil Monitoring Field Experiments
Table 1 outlines the long-term field experiments. The project lasted from 1975 to 1997. However, some experimental sites were discontinued because of translocation of the experimental stations and other reasons. Paddy field sites totalled 122 and upland field sites 116. Experimental sites were placed in fields of the soil type representative of each prefecture, and almost all soil types in Japan were represented. Each experiment was representative of the crops, crop rotation, amount of fertilizer and organic matter, and method of cultivation of each prefecture. Fertilizer treatments usually consisted of chemical fertilizer as control, no-nitrogen chemical fertilizer (i.e., applied chemical potassium and phosphorus fertilizer), organic matter added to chemical fertilizer, and organic matter plus soil amendment added to chemical fertilizer. In paddy fields, 5 Mg ha-1 rice straw or 10 Mg ha-1 rice straw compost application was common. In upland fields, 10-20 Mg ha-1 rice straw compost or animal manure compost application was common. Data on fertilizer, crop, soil, damage (i.e., climate damage, disease and insect damage) were collected, however, some data were lacking for some sites.
Structure of the Long-Term Soil Monitoring Database (Fig. 1)
The database consists of four types of files: site information, cropping system, soil analysis data, and soil profile. Site information files contain address, soil type, and duration of the experiment site. Cropping system files consist of site worksheets, each of which has soil and fertilizer management data and crop information data such as crop residue treatment method, rate of chemical fertilizer and organic matter application, type and variety of crop, and cropping system. Soil analysis data files comprise site worksheets of soil property data. Soil profile files comprise the soil profile description data at each site at the beginning and end of experiment. This database has a web browser data retrieval function as an interface for users.
Retrieving Data from the Database (Fig. 2)
The first step is site (i.e., prefecture) selection, then selection of fertilizer treatments, crop types, cropping systems, and soil types (i.e., soil groups) according to Classification of Cultivated Soils in Japan Second Approximation (National Institute of Agricultural Sciences 1983).
The second step is selection of output items: information on site, soil type, crop yield and nutrient uptake, fertilizer, soil analysis data, and damage ( Table 2).
The last step is display of retrieved results. Displayed results can be saved in Excel format and used for further data analysis.
Effect of Fertilizer Management Treatments on Paddy Rice Yields and Soil Properties
General Information on Paddy Rice Fields in Japan
Fig. 3 shows changes in the area of paddy rice fields and the rice planted area in Japan. The area of paddy rice peaked at 3.44 million ha in 1969, then gradually decreased to 2.54 million ha in 2006. The planted area also peaked in 1969, at 3.17 million ha, then gradually decreased to 1.68 million ha in 2006. The area of abandoned arable lands has increased to 0.39 million ha in 2005, owing to the aging of farming communities.
Soil groups of Japanese paddy soils are shown in Fig. 4, according to the Classification of Cultivated Soils in Japan Second Approximation (National Institute of Agricultural Sciences 1983). Gray Lowland soil and Gley soil, i.e., very poorly to poorly drained soils, distributed mainly in flood plain and back marsh, comprise two-thirds of the paddy soils. Relatively well drained soils such as Yellow soil, Brown Lowland soil, and Wet Andosol account for around 20% of the paddy soils.
Methods for Analyzing the Effects of Fertilizer Management on Rice Yield and Soil Properties
Data for 43 paddy field experimental sites that continued for more than 15 years were retrieved. Fertilizer treatments were sorted in six different types: 1) chemical fertilizer (CF) treatment as a control, CF; 2) CF plus rice straw treatment (ST), CF+ST; 3) CF plus ST and soil amendment (AM), CF+ST+AM; 4) CF plus compost (animal manure compost and rice straw compost) (CM) 10 Mg ha -1 or less than 10 Mg ha -1 treatment, CF+CM <10); 5) CF plus CM 10 to 20 Mg ha -1 treatment, CF+CM (10-20); 6) CF plus CM more than 20 Mg ha -1 treatment, CF+CM (>20).
In the CF+ST and CF+ST+AM treatments, rate of rice straw application was usually 5 or 6 Mg ha -1, and soil amendments were calcium silicate and/or fused magnesium phosphate. In the compost treatments, rice straw compost was applied at 15 experimental sites, animal manure compost at 14 sites, and type of compost was unknown for 5 sites. In the CF+CM (<10) treatments, rate of compost application was 10 Mg ha -1 in 22 out of 24 sites. In the CF+CM (10-20) treatments, rate of compost application was 20 Mg ha -1 at 5 sites, 15 Mg ha -1 at 3 sites, 14 Mg ha -1 at 1 site, and 12 Mg ha -1 at 1 site. In the CF+CM (>20) treatments, application rate was 30 Mg ha -1 at 7 sites, and 40 Mg ha -1 at 2 sites. Plant residue, i.e., rice straw, was removed from the fields without the CF+ST and CF+ST+AM treatments.
This project analyzed the effect of the additional application of rice straw or compost on rice yields and soil properties by district or soil type.
Effect of Fertilizer Management on Rice Yield
Table 3 shows the indexes of yields at each site and each treatment during the experiments by district. Mean rice yields for the last 3 years in the CF treatments ranged from 4.53 to 7.03 Mg ha -1. Nationwide average rice yield in the CF treatments was 5.52 Mg ha -1, with higher-than-average yields in the Hokkaido, Tohoku, and Hokuriku districts (more than 5.70 Mg ha -1), and lower-than-average yields in the Kanto, Tokai, Kinki, and Kyushu districts (less than 5.40 Mg ha -1).
The CF treatment was used as the standard, with an index of 100. The averages of indexes of yield by treatments in Japan are:
CF+CM (<10) = 103
CF+ST, and CF+CM (>20) = 104
CF+ST+AM = 105
CF+CM (10-20) = 107
These averages are significantly higher (P < 0.05) than those for the CF treatment by paired t-test (SPSS, Tokyo, Japan).
In the CF+ST and the CF+CM (<10) treatments, rice yields increased in 17 out of 30 sites and 12 out of 24 sites, respectively, i.e., index was 103 or more than 103. In the CF+ST+AM, the CF+CM (10-20), and the CF+CM (>20) treatments, rice yields increased in almost 80% of the sites.
The effect on rice yield of rice straw application usually at 5-6 Mg ha -1 corresponded to compost application of 10 Mg ha -1. In the Hokkaido and Tohoku districts in northern Japan, however, rice straw application at 5 out of 7 sites did not affect rice yield. This result may be attributed to organic acids (aromatic acids), which inhibit growth of rice roots, produced by decomposition of straw during early growth of rice (Tanaka et al. 1990). The CF+CM (<10) treatments in 7 out of 10 sites in the Hokkaido and Tohoku districts also did not increase rice yield. On the other hand, at the most sites in Kinki and Kyushu districts, straw or compost application increased rice yields.
Table 4 shows yield indices during the experiments by soil type. In Yellow soils, Gravelly Gray Lowland soils, and Medium and Coarse-textured Gley soils of relatively lower soil fertility, straw or compost application increased rice yields. On the contrary, their application on Strong-gley soils and Fine-textured Gley soils, i.e., poorly drained soils, for organic matter application enhanced reducing conditions, rarely increasing rice yields. On Andosols, Fine-textured Gray Lowland soils, and Medium and Coarse-textured Gray Lowland soils, ST+CM (<10) application had no effect on rice yields or reduced rice yields on some sites.
Effect of Fertilizer Management on Soil Properties
From the database, soil property data sets from the sites that continued for 15-23 years were selected. Thirty-eight sites in the database contain total carbon and nitrogen data of the CF treatments. Figs. 5, 6 and 7 show the average of the data for the last 3 years.
Fig. 5 shows the relationship between T-C contents of the CF and the CF+ST or CF+CM (<10) treatments in paddy fields. These results indicate that the CF+ST and CF+CM (<10) treatments have slightly higher carbon content than CF treatments in almost all sites. As the IPCC (2006) reported, soil is the focus of carbon sequestration in global warming. Results of this project show that continuous organic matter application to paddy fields contributes to soil carbon storage.
Fig. 6 shows the indexes and averages of soil properties. CF treatment was used as the standard with an index of 100. Indexes were calculated for each site, and then averaged by treatment. In the CF+ST, CF+ST+AM, CF+CM (<10), and CF+CM (10-20) treatments, total carbon contents increased significantly (P < 0.01) by 16, 13, 17, and 34 points, respectively, compared with CF. Trends of increases in total nitrogen content as a result of organic matter application were similar to those for total carbon content. CEC was also increased significantly (P < 0.05) by organic matter application, by 3, 9, 7, and 15 points in the CF+ST, CF+ST+AM, CF+CM (<10), and CF+CM (10-20) treatments, respectively. Organic matter application also positively affected physical properties; bulk density decreased significantly (P < 0.05) by 5, 5, 5, and 7 points in the CF+ST, CF+ST+AM, CF+CM (<10), and CF+CM (10-20) treatments, respectively. These results indicate that returning rice straw to the field is comparable to 10 Mg ha -1 compost application for improving soil properties such as total carbon and nitrogen content, CEC, and bulk density. These trends for the effectiveness of organic matter application are consistent with those in previous reports (Uwasawa 1991, Yamashita 1967, Reeves 1997).
The correlations between total carbon and nitrogen content, CEC, and porosity were positive and high (P < 0.01), and between total carbon content and bulk density were negative and high (P < 0.01) ( Fig. 7). There were no relationship between total carbon content and exchangeable bases and available phosphorus. These relationships mean that total carbon content affects chemical and physical soil properties, especially the properties related to fundamental soil fertility in paddy fields.
Kusaba and Ishioka (2008) established a database of the results of about 20 years of continuous long-term field soil monitoring field experiments conducted in all prefectural agriculture experiment stations in Japan. This database contains data on the rate of applied fertilizer and compost, crop yields, and soil properties, and has a retrieval function. Using this database, nationwide changes in soil properties and crop yields in paddy fields were examined. Results show that organic matter application increased rice yields and improved soil properties such as total carbon and nitrogen contents, CEC, and bulk density. The relationships between total carbon and nitrogen content, CEC, and bulk density are highly correlated, which indicates that total carbon content affects chemical and physical soil properties, especially those related to fundamental soil fertility in paddy fields. The effective use of such nationwide information on the changes in crop yields and soil characteristic is important not only for sustainable agriculture, but also for understanding environmental issues.
- IPCC. 2006. IPCC Guideline for National Greenhouse Gas Inventories.
- IPCC. 2007. IPCC Fourth Assessment Report (AR4): Climate Change 2007, Cambridge University Press. http://www.ipcc.ch/
- Kamimura, Y., K. Furue, and N. Nishizono. 1994. Improvement of paddy soil derived from glassy volcanic ash (Shirasu) by successive applications of organic and inorganic amendments. Soil Sci. Plant Nutr. 40. 39-48.
- Kusaba, T., and G. Ishioka. 2008. Outline and characteristics of the Dojyo Kankyo Kisochousa Kijunten Chousa Database: database of long-term changes in soil properties and crops yields of arable field under nutrient managements in Japan (in Japanese).
- Maeda, K., 1974. The physical properties of the paddy field soil treated with the successive application of rice straw. J. of Jpn. Soc.Soil Physics. 30. 33-38 (in Japanese).
- Natl. Inst. of Agricultural Sciences. 1983. Classification of Cultivated soils in Japan Second Approximation. Misc. Publ. Natl. Inst. Agricultural Sciences.P.75.
- Reeves, D.W. 1997. The role of soil organic matter in maintaining soil quality in continuous cropping systems. Soil and Tillage Research. 43. 131-167.
- Tanaka, F., S. Ono, and T. Hayasaka .1990. Identification and evaluation of toxicity of rice root elongation inhibitors in flooded soils with added wheat straw. Soil Sci. Plant Nutr. 36: 97-103.
- Tatsumi, M., T. Tomoji, S. Yoshimura, S. Sumi, and S. Nishigaki. 1985. Effects on rice yield and nutrient components by application of rice straw to paddy fields. Bull. Osaka Agr. Rec. Cent. 22. 25-30 (in Japanese with English summary).
- Uwasawa, M. 1991. National survey of soil productivity and crop yields obtained from long-term composted and noncomposted field experiments. Nogyou Gijutsu . 46. 393-397 (in Japanese).
- Yamashita, K. 1967. The effects of the prolonged application of farmyard manure on the nature of soil organic matter and chemical and physical properties of paddy rice soils. Bull. Natl. Agric. Rec. Cent. for Kyushu.13.113-156 (in Japanese with English summary).
Index of Images
Figure 1 Structure of the Long-Term Soil Monitoring Database.
Figure 2 Procedure for Data Retrieval from the Long-Term Soil Monitoring Database.
Figure 3 Changes in the Area of Paddy Fields and Rice Planted Area in Japan.
Figure 4 Soil Groups in Japanese Paddy Fields.
Figure 5 Relationship between Total Carbon Content of Chemical Fertilizer (CF) and CF Plus Straw (CF+ST) or CF Plus Compost (CF+CM (<10)) Treatments.
Figure 6 Indexes and Averages Soil Property Data of the Last 3 Years in the Long-Term Paddy Field Experiments
Figure 7 Relationship between Total Carbon Contents and Other Soil Properties in CF and CF+CM (?10) Treatments in Long-Term Paddy Field Experiments.
Table 1 Outline of the Long-Term Field Experiments
Table 2 Output Items in the Long-Term Soil Moritoring Database
Table 3 Average Yield Index by District during the Experiment Period
Table 4 Average Yield Index by Soil Type during the Experiment Period
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