In light of this, even with the technical capability to perform a wide spectrum of analyses and determine soil fertility through various methods, most of them are quite labor-intensive and, in practice, do not allow correlating the properties of the soil cover of agricultural land parcels with the necessary spatial and/or temporal resolution.
We are developing a rapid method for determining the fertility parameters of soils for agricultural lands, based on radar methods of measuring the chemical composition of soils. This method utilizes a blend of spectrometric and radar data, seeking to deliver not only a quick assessment but also to substantiate the accuracy and reliability of such rapid diagnostics of the soil state.
Integrating Radar Methods for Precision in Agricultural Lands Assessment
The radar methods we develop aim to optimize the inputs and actions based on precise diagnostics and, as a result, to minimize the environmental footprint and ensure the sustainability of agricultural practices. The method involves deploying radar technologies that utilize electromagnetic waves to penetrate the soil, obtaining data about its structure and characteristics. Subsequently, these data are analyzed in combination with spectrometric methods, which allow for determining the chemical composition of the soil without direct contact.
This interdisciplinary approach, combining radar and spectrometric methodologies, provides a comprehensive profile of the soil, revealing aspects related to its physical state, moisture content, and chemical makeup. The ultimate goal is to facilitate data-driven decisions in agricultural practice, ensuring that the soil is managed and utilized in a way that sustains its fertility and health while optimizing crop yield and minimizing negative environmental impacts.
Through careful calibration and validation against traditional laboratory soil tests, this method aims to provide a powerful tool for farmers and agricultural researchers. It is designed to guide precise interventions, such as the targeted application of fertilizers and other amendments, ensuring that the crops receive precisely what they need for optimal growth, while environmental impacts are mitigated.
Further research and field tests will substantiate the efficacy and applicability of this method in various agricultural contexts, paving the way toward more sustainable and precise agriculture.
The utilization of Infrared (IR) Spectroscopy, long recognized as one of the most promising methods for soil study is founded on the interaction of molecules with electromagnetic energy in the IR spectrum region. A distinctive feature of the mid-IR range is that it encompasses so-called fundamental molecular vibrations. When a molecule absorbs IR radiation at frequencies corresponding to its intrinsic vibrations, it leads to an amplification of vibrational amplitudes. Since each frequency corresponds to a specific energy quantity and distinct molecular motion (e.g., stretching, bending of chemical bonds), the mid-IR spectrum allows the identification of molecular motion types and functional groups present in the molecule. Consequently, this information can serve as a unique characteristic of the soil, akin to a human fingerprint in dactyloscopy.
Field studies utilizing spectroscopy methods, in our case, are determined by the need to establish STANDARD characteristics of the soils under investigation, to conduct comparative analysis of data obtained through spectrometric and radar methods.
The objectives solved using these methods in the field of soil research are reduced to their use for assessing trace elements and organic substances in the soil. Such soil mineral elements as C, N, P, K, S, Ca, and trace elements play a pivotal role in the development of agricultural crops and, consequently, determining their concentrations is crucial for the application of precision farming concepts. There are quite a substantial number of publications on this topic in scientific literature. One of the best overviews of research in this direction, using spectroradiometric methods, has been prepared in 2006 by a team of authors Rossel R.A.V., Walvoort D.J.J., McBratney A.B., Janik L.J., Skjemstad J.O. in the study "Visible, near-infrared, mid infrared or combined diffuse reflectance spectroscopy for simultaneous assessment of various soil properties".
The most common approach involves searching for correlational relationships between the element content and the spectral brightness indicator, and in our case, the reflection/absorption indicators of radio waves of a certain range. In the overwhelming majority of studies, strong correlational relationships (above 0.9) between the organic carbon content in the soil and the spectral brightness indicator are noted. High values (R>0.80) were also obtained for the total nitrogen content. Although no correlations for nitrates were found in the study Rossel R.A mentioned above.
This conclusion is refuted by strong correlational relationships with spectral brightness obtained by other research teams, e.g. Linker R., Kenny A., Shaviv A., Singher L., Shmulevich I. "Fourier transform infrared-attenuated total reflection nitrate determination of soil pastes using principal component regression, partial least squares, and cross-correlation", Borenstein A., Linker R., Shmulevich I., Shaviv A. "Determination of soil nitrate and water content using attenuated total reflectance spectroscopy" and Jahn B.R., Linker R., Upadhyaya S.K., Shaviv A., Slaughter D.C., Shmulevich I. "Mid-infrared spectroscopic determination of soil nitrate content".
Pertaining to potassium, phosphorus, and organic substances, contradictory results have been obtained. In studies Du C.W., Zhou J.M., Wang H.Y., Chen X.Q., Zhu A.N., Zhang J.B. "Determination of soil properties using Fourier transform mid-infrared photoacoustic spectroscopy"., the correlation coefficient for potassium concentration was 0.85. Some studies report lower correlation coefficients R=0.6 and R=0.76. A high degree of connection is noted for phosphorus – R=0.87 and R=0.81. Despite significant results for organic substances reflected in studies Masserschmidt I., Cuelbas C.J., Poppi R.J., De Andrade J.C., De Abreu C.A., Davanzo C.U. "Determination of organic matter in soils by FTIR/diffuse reflectance and multivariate calibration" with correlation coefficient values above 0.90, a very weak correlation between spectra and the content of organic matter was determined.