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Poster Session
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Influence of the cultural practices to the reflecting spectra in the wheat fields
Zhang Hongmin, wang Jiashen, Zhang Xioping,
Lu Zhiguang and Cao Daicheng
Agricultural Remote Sensing Center of Beijing Agricultural
University
Beijing, China
Abstract
This article deals with the influence of the main cultural practices (including the different sowing period, the different planting density and the different fertilizer level,ect.) to the reflecting spectra in the wheat fields through the field experiment analysis. The results show that the difference of fertility has the greatest influence on the wheat infrared reflection and the different ridge types make the spectra-reflecting rate of relay intercropping in the wheat fields lower than the flat furrow ploughing wheat fields.
Introduction
To monitor and estimate the yield of the crops by the way of remote sensing information, the main basis is the characteristic of the reflecting spectra of the crops in the fields. But in fact, the characteristic of the crop spectra in the fields is a kind of comprehensive reflecting result of a combined spectrum. it depends not only on the conditions of crops themselves, but on the influence of the background of the soil condition. The crops themselves may show various growth situations because of the various cultural practices so as to obtain the spectra characteristic under different conditions. To monitor and estimate the yield of crops in a large area by the way of remote sensing method, that is to utilize these different spectra reflections to understand the different growth conditions of the crops and judge the possible causes of these conditions and its influence to the yield.
At first, to understand the influence of some main cultural practices for the wheat spectra in the fields through the field remote sensing experiments must be the important components of the research to monitor and estimate the wheat yield by remote sensing. We carried
out the spectra observation of the different crop conditions due to the various cultural practices, planting density, fertilizer level and showing early or late by the way of the different productive plots in the fields and special field tests. Now the preliminary results were analyzed as follows and for the reference of remote sensing image interpretation.
Research Arrangement
The whole research program was carried out in two experimental areas from 1987 to
1988.
- Tongxian Country Experimental Area:
Together with the Tongxian Agricultural Extension Station, two kinds of plots were selected for the observation. The first kind was the wheat field with two types of wheat culture and different ridge width; one with 2.5m broad ridge width and the other with 1.5m narrow ridge width. The second kind was the wheat field with different fertilizer level. Its experimental treatment was with 225kg/ha,112.5kg/has and without ammonia sulphuric as the basic fertilizer and with different dressing fertilizer during the wheat reviving stage and elongation stage. All the wheat variety was the Noida 146 and the soil texture was loam. There were two different sowing variety was the Nonda 146 and the soil texture was loan. There were two different sowing periods: one early sowing on 22-24 Sep., the other late sowing on Oct.4.
- Malianwa experimental Area:
This area was near Beijing Agricultural University. Its soil and wheat variety wheat variety were similar to the of Tongxian Country experimental area. In order to gain various experimental combination data without too many treatments, the orthogonal rotary regression design was adopted there were two factors: Sowing density and fertilizer level, with five ranks. The greatest density was 4,080,000 seedlings per hectare and the smallest 1,200,000 seedlings per hectare. The different range between the ranks was 1018,500 seedlings. The greatest basic fertilizer was 300 kg/ha N and 150 kg/ha P. the smallest was without basic fertilizer. The different range between the ranks was 1018,500 seedlings per hectare and the smallest 1,200,000 seedlings per hectare. The different range between the ranks was 1018,500 seedlings. The greatest basic fertilizer was 300kg/ha N and 150kg/ha. P. The smallest was without basic fertilizer. The different range between the ranks was 106.05kg N and 57.7kg P.
- Observation Method:
With the four spectrum ranges, i.e. 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-1.1 of American 100 AX-M spectror and the four spectrum rangs, i.e. 0,45-0.52, 0.52-0.6, 0.63-0.69, 0.76-0.90 of the Chinese RS-II-type spector, the spectra were determined during the main wheat growth stages. During fine weather without wind at 10:00-14:00 noon, the spectrum surveying was carried out to make the main ray axis of lens vertical to the wheat canopy and over the canopy 1.2m. Every treatment was reassured for 9 times, to record and count with auto-microcomputer.
During the spectrum observation, the wheat samples were carried out to take the plant dry-fresh weight, LAI and the chlorophyII content,etc.
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