Study Of The Soil And Crop Information Collection And Their Relationships Based On Spectroscopy Technique

With the development of GPS, GIS, RS, VRT and DS, precision agriculture as a new technology has emerged since 1990s. The kernel of this technology is to obtain the yield production of the small section, the spatial and temporal information of the environmental factors (soil structure, topographic form, crop nutrition, water content and plant diseases and insect pests et al.), which influence the growth of the crop, and then adopt the appropriate measurement to realize "prescription farming" by analyzing the reasons of these factors.Precision agriculture is an integrated application of the advanced technology, especially the information technology in the agricultural production. It consists of information obtain system, information treatment system, and intelligent mechanization of farming. Information obtain system is the base and thereunder of the precision agriculture in the practices of its operation, so it is very necessary to systemically and roundly analyze the obtain techniques and disposal methods of the field information (soil information, crop information, yield and quality information of the crops).Considering the actual situation of our country, and the problems and deficiencies of the present technology in the information obtain system, we systemically and roundly analyzed the soil information in the oilseed rape field, crop information in the growth of the oilseed rape, the relationships between the soil information and chlorophyll content, oilseed rape yield and quality information. Quadratic regression orthogonal design was applied in this research to design the fertilization level. Three factors (nitrogen fertilizer, phosphorus fertilizer, kalium fertilizer) were considered in this research, and the field was in the condition of deficiency fertilizer, normal fertilizer and excessive fertilizer manually. The main contents and conclusions were as follows:1) The influence of measurement area to soil spectral properties and water content prediction were analyzed in this research by using the handheld spectrophotometer (ASD). Geometric method was also been used to validate the above conclusion, and the mathematic model was founded according the position of the spectrophotometer to the object in the process of the measurement. This model can be applied in the outdoor measurement. It can estimate the measurement area according with the measurement height, or estimate the measurement height according with the measurement area. It is obviously that it can avoid the influence of the background information during the process of the spectra collection.2) Spectral properties of the raw soil samples (in the natural condition, soil samples was simply treatment) were analyzed by using NEXUS intelligent Fourier transform (FT) infrared spectorscopy, and the quantitative analysis model was founded to the soil nitrogen (N), available phosphorus (P), available kalium (K), organic matter (OM) content and pH. The result shows that it can predict OM content and pH value commendably with the l_st derivate spectra, and the correlation coefficient is up to 0.8. Orthogonal signal correction (OSC) method as a new pretreatment method to the spectra wasapplied in this research during the processes of the OM content prediction. It can improve the prediction ability greatly, and the correlation coefficient achieved to 0.89. During the analysis of the nitrogen content prediction, we found that particle size influence the nitrogen prediction ability greatly. The prediction ability to the P and K are not satisfied as our expected, the correlation coefficient is 0.661 and 0.721 respectively, so it needs a further research.3) SPAD 502-chlorophyll meter was used in this research to analyze the variability of chlorophyll content during the growth stage of the oilseed rape. Spatial analysis module of Arc View 3.2 software was used to analyze the spatial distribution rule of the SPAD values, which can reveal the distribution of SPAD intuitionisticly and accurately. The result shows that different measurement part has different SPAD values. The third leaves counted from the above were selected as our research object. The variation law of SPAD values in different growth stage and different fertilizers levels was detailed analyzed in this research. The result shows that interim of the bud and anthesis is the best time for nitrogen management. It will be helpful for the nitrogen management to this field.4) Spectral properties of oilseed rape leaves were analyzed in this research by using handheld spectrophotometer. The result shows that the sensitive brands to SPAD values are 676nm and 684nm, respectively, and the correlation coefficient is 0.923. The relationship between the SPAD value and the red edge and green edge was also analyzed. The result shows that two variables (red edge and green edge) can better predict the SPAD values of the oilseed rape leaves than the one variable (red edge).5) The quantitative analysis model was founded to soil fertilizer and SPAD values, and the result shows that nitrogen fertilizer is positively correlative to SPAD values. This result futherly demonstrated that SPAD could reflect the nitrogen fertilizer. The quantitative analysis model was also founded to soil fertilizer and yield of oilseed rape. The result shows that nitrogen fertilizer is positively correlative to the yield. The yield increased with the increase of the nitrogen fertilizer. Kalium fertilizer is sensitive to the yield when the kalium fertilizer is deficient, that is, when the kalium fertilizer is deficient, the yield is lower, while when it is in the normal or excessive condition, the yield has no more significant change. Phosphorus fertilizer has no more significant role to the yield in all stage.6 ) Quadratic regression orthogonal design was used to analyze the relationships between the oil content of oilseed rape, glucosinolate content, and erucic acid content and the fertilizer. The result shows that nitrogen fertilizer affected the oil content greatly. When the nitrogen fertilizer was excessive, nitrogen fertilizer is negative correlative to oil content and glucosinolate content. Excessive phosphorus fertilizer can reduce the glucosinolate content, and kalium fertilizer is significant to erucic acid at the 0.1 levels. Erucic acid content increased with the increase of the kalium fertilizer. The interaction of the fertilizer to oilseed rape quality was also analyzed in this paper. The result shows that interactions of the nitrogeous fertilizer and kalium fertilizer affect the oil content greatly, and the interactions of the phosphorus fertilizer and kalium fertilizer affect the glucosinolate content and erucic acid content greatly.7) To improve the yield and quality of the oilseed rape, nonlinear programming model was founded in this paper to find the best scheme of fertilizer. The result shows that different research object has different conclusions. Excessive nitrogen fertilizer can improve the yield of oilseed rape, while it will decrease the oil content and increase the glucosinolate content at the same time. Excessive phosphorus fertilizer can decrease the glucosinolate content, but it will affect the oil content of the oilseed rape. In order to realize the objective of the high yield and quality, this paper suggests that when the the urea (46%) is between the 22.23-29.87kg, superphosphate (powder, 16%) is between the 1.7-1.84kg, and potassium chloride (60%) is between the 1.71-16.67kg in a unit of area, the lower erucic acid content and higher oil content will be obtained, relatively. When the the urea (46%) is between the 28.53-48.76kg, superphosphate (powder, 16%) is between the 43.5-53.86kg, and potassium chloride (60%) is between the 23.1-31.62kg in a unit of area, the lower glucosinolate content and higher yield will be obtained, relatively.