Effect of Organic Farming Duration on Soil and Vegetables
Date Issued
2010
Date
2010
Author(s)
Tsai, Tung-Jung
Abstract
The major objects of this study is to find out the effect of long-term organic farming on the soil physic-chemical properties and the crop growth, and to investigate the feasibility of applying the real-time analysis, based on the remote-sensing science, to improve the organic agricultural management and the corp quality control. At the meantime, the issues of global warming and carbon reduction were highly-concerned; we also try to exam the capability of soil organic carbon (SOC) stock of the organic farming. The results of the study are shown as follows：
(1) After the long-term organic farming, the soil pH got a rising trend (> pH 5.0). The content of organic matter, organic carbon, bio-available phosphorus, exchangeable potassium, exchangeable magnesium, and exchangeable calcium are increased with the duration of the organic cultivation. These indicate the long-term organic farming can improve the soil condition.
(2) The increasing of organic cultivation duration can raise the height and dry weight, in addition, can stabilize the plant absorption of the nutrimental elements. In addition to increase the content of the potassium and zinc in vegetables, it reduces the content of the sodium.
(3) The increasing of organic farming duration can been shown by a specific regular pattern of the leaf spectral reflectance at the wavelength of visible light and near infra-red regions, and been coincided with the variation of the photosynthetic pigments content. The vegetation index, such as NDVI, SRVI, NDVIbroad and SRVIbroad, and the value of SPAD can be served as the pointers, when the senescence of the organic cultivated-plants and the reduction of the chloroplast are happened. By utilizing reflectance spectrum to calculate vegetation index and to measure the variation of the pigment content in leaves, and to monitor the whole crop growth condition, finally.
(4) In the greenhouses with different duration of organic cultivation, the SOC content within 20 cm-depth from soil surface was increased about 100 to 900 Mg ha-1 (i.e. 370 to 3,300 Mg CO2 ha-1 was got fixed.) throughout a vegetable cultivating cycle. The soil in the greenhouse with different duration of organic farming (from 1 to 7 years) can stock 3,100 to 5,600 Mg ha-1 SOC, which is equivalent to 11,400 ~ 20,600 Mg CO2 ha-1. Under long-term organic cultivation, there is 1400 Mg CO2 ha-1 got fixed each year. The SOC could keep accumulated to the maximum amount while the organic farming was continued more than 5 to 7 years. Evidently, to popularize the organic agricultural management in the future will get benefit from CO2 reduction, promotion of the agricultural crop value, and maintenance of even more healthy cropping fields and products. Eventually, we wish to reach a balance between crop production / quality, environmental protection, and sustainable cultivating environment.
Subjects
organic farming
photosynthesis pigment
reflective spectrum
element analysis
soil organic carbon
SDGs
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