Cosmic Ray Neutron Sensing: Estimation of Agricultural Crop Biomass Water Equivalent

Earth Science; Soil Management; Water Management; Crop Nutrition; Nuclear; CRNS; Biomass Water Equivalent; Remote Sensing; Satellite Imager

Cosmic Ray Neutron Sensing: Estimation of Agricultural Crop Biomass Water Equivalent

This open access book provides methods for the estimation of Biomass Water Equivalent (BEW), an essential step for improving the accuracy of area-wide soil moisture by cosmic-ray neutron sensors (CRNS). Three techniques are explained in detail: (i) traditional in-situ destructive sampling, (ii) satellite based remote sensing of plant surfaces, and (iii) biomass estimation via the use of the CRNS itself. The advantages and disadvantages of each method are discussed along with step by step instructions on proper procedures and implementation

Cosmic Ray Neutron Sensing: Estimation of Agricultural Crop Biomass Water Equivalent

Earth Science; Soil Management; Water Management; Crop Nutrition; Nuclear; CRNS; Biomass Water Equivalent; Remote Sensing; Satellite Imager

The identification and significance of inputs to Anthrosols in North-West Europe

In recent years there has been a renewed interest in soils which are the result of past land management practices involving substantial additions of mineral and organic matter. However, there is still a substantial lack of detailed information on their formation. Anthrosols are distinguished by the presence of a deep top horizon and such soils were investigated at sites in Scotland, Denmark and The Netherlands. Field data and samples were collected from eight sites under arable cultivation, meadowland and woodland. Particle size distribution, pH, loss on ignition, ECEC, base saturation and total P were measured. Carbonaceous particles were identified through micromorphological analysis and the determination of O:C ratios using an electron microprobe. Despite the use of different inputs in recent centuries and different current land management, the resultant anthropogenic soils are remarkably similar in field and analytical properties. Nevertheless, subtle changes in particle size can be explained by parent material influences, material imported by farmers and by inputs by other processes such as by wind. The results from microprobe analysis demonstrate the importance of carbonaceous particles in storing phosphorus. Thus the inherent fertility of these Anthrosols can be explained in part by the application of carbonised material in the past

Estimation of medium-term soil redistribution rates in Ibadan, Nigeria, by using the 137 Cs technique

Soil erosion is a widespread and serious problem in Nigeria, West Africa. The 137 Cs technique is an alternative to field plots for generating data on medium-term soil redistri bution. It was tested in 2007 in Ibadan, Nigeria, which means the firs t time in the derived savanna. To analyse the vertical and spatial distribution of this nuclide in the soil, core samples were taken either randomly or along transects in an uncultivated and a cultivated site. The study showed an accumulation of 137 Cs near the soil surface and a slow decr ease with depth in the undisturbed site. The arable land was characterized by an almost uniform 137 Cs distribution within the ploughed layer. The reference inventory of 137 Cs determined on the uncultivated site was 569.3 ± 150.1 Bq m -2 ; the inventory of 137 Cs on the field ranged from 96.9 to 1494.4 Bq m -2 . Comparisons with the reference inventory showed smaller values for the upper slope and higher values for the lower slope of the cultivated site, wh ich indicated soil redistribution. The conversion of the inventories into quantitative data of erosi on and deposition by a proportion model revealed, for example, that about 148.5 t ha -1 yr -1 were eroded from the cropland in furrows leading downslope. The estimated results were comparable to erosion measurements made nearby. Hence, the 137 Cs technique is useful as a method to generate data on soil redistribution a nd therefore a tool for improved natural resource management in Nigeria

Using Cosmic-Ray Neutron Probes to Monitor Landscape Scale Soil Water Content in Mixed Land Use Agricultural Systems

With an ever-increasing demand for natural resources and the societal need to understand and predict natural disasters, soil water content (SWC) observations remain a critical variable to monitor in order to optimally allocate resources, establish early warning systems, and improve weather forecasts.However, routine agricultural production practices of soil cultivation, planting, and harvest make the operation andmaintenance of direct contact point sensors for long-termmonitoring challenging. In this work, we explore the use of the newly established Cosmic-Ray Neutron Probe (CRNP) and method to monitor landscape average SWC in a mixed agricultural land use systemin northeastAustria.Thecalibrated CRNP landscape SWC values compare well against an independent in situ SWC probe network (MAE = 0.0286m3/m3) given the challenge of continuous in situ monitoring from probes across a heterogeneous agricultural landscape. The ability of the CRNP to provide real-time and accurate landscape SWC measurements makes it an ideal method for establishing long-term monitoring sites in agricultural ecosystems to aid in agricultural water and nutrient management decisions at the small tract of land scale as well as aiding in management decisions at larger scales

AquaCrop: calibration of new crops

Extended core group meeting on AquaCro

Testing a novel sensor design to jointly measure cosmic-ray neutrons, muons and gamma rays for non-invasive soil moisture estimation

Cosmic-ray neutron sensing (CRNS) has emerged as a reliable method for soil moisture and snow estimation. However, the applicability of this method beyond research has been limited due to, among others, the use of relatively large and expensive sensors. This paper presents the tests conducted on a new scintillator-based sensor especially designed to jointly measure neutron counts, muons and total gamma rays. The neutron signal is first compared against two conventional gas-tube-based CRNS sensors at two locations. The estimated soil moisture is further assessed at four agricultural sites, based on gravimetric soil moisture collected within the sensor footprint. Muon fluxes are compared to the incoming neutron variability measured at a neutron monitoring station and total gammas counts are compared to the signal detected by a gamma ray spectrometer. The results show that the neutron dynamic detected by the new scintillator-based CRNS sensor is well in agreement with conventional CRNS sensors. The derived soil moisture also agreed well with the gravimetric soil moisture measurements. The muons and the total gamma rays simultaneously detected by the sensor show promising features to account for the incoming variability and for discriminating irrigation and precipitation events, respectively. Further experiments and analyses should be conducted, however, to better understand the accuracy and the added value of these additional data for soil moisture estimation. Overall, the new scintillator design shows to be a valid and compact alternative to conventional CRNS sensors for non-invasive soil moisture monitoring and to open the path to a wide range of applications.</p

The impact of soil chemistry, moisture and temperature on branched and isoprenoid GDGTs in soils: A study using six globally distributed elevation transects

Glycerol dialkyl glycerol tetraethers (GDGTs) are microbial membrane-spanning lipids that are produced in a variety of environments. To better understand the potentially confounding effect of soil chemistry on the temperature relationship of branched GDGTs (brGDGTs), isoprenoid GDGTs (isoGDGTs) and GDGT-based proxies MBT’5ME and TEX86, soils from 6 elevation transects (mean annual air temperature 0 – 26 ℃, n = 74) were analyzed. Corroborating earlier work, the MBT’5ME index correlates well with mean annual air temperature in the low pH (pH < 7), non-arid soils under study (r = 0.87, p < 0.001). However, a clear over-estimation of reconstructed temperature in the lowest pH (<3.5) soils is observed, explained by the correlation between brGDGT Ia and free acidity. TEX86 also shows a significant correlation with mean annual air temperature (r = 0.45, p < 0.001), driven by temperature dependent concentration changes of isoGDGTs 3 and cren’. However, an overarching correlation with P/E values dominates concentration changes of all supposed Thaumarchaeotal isoGDGTs lipids (GDGT1-3, cren and cren’), implying a potential impact of soil moisture on TEX86 values. In addition to identifying the impact of these confounding factors on the temperature proxy, GDGT ratios that can be used to constrain changes in soil chemistry, specifically exchangeable Ca2+, sum of basic cations, exchangeable Fe3+ and sum of soil metals are proposed (0.53 < r2 < 0.68), while existing ratios for soil moisture availability are tested for the first time in a dataset of non-arid soils. While the impact of soil chemistry on GDGTs may complicate the interpretation of their temperature proxies, our proposed GDGT ratios can potentially be used to constrain a subset of soil chemistry changes through time