Synthetic aperture radar (SAR) data provides an appealing opportunity for all-weather day or night Earth surface monitoring. The European constellation Sentinel-1 (S1) consisting of S1-A and S1-B satellites offers a suitable revisit time and spatial resolution for the observation of croplands from space. The C-band radar backscatter is sensitive to vegetation structure changes and phenology as well as soil moisture and roughness. It also varies depending on the local incidence angle (LIA) of the SAR acquisition’s geometry. The LIA backscatter dependency could therefore be exploited to improve the retrieval of the crop biophysical variables. The availability of S1 radar time-series data at distinct observation angles holds the feasibility to retrieve leaf area index (LAI) evolution considering spatiotemporal coverage of intensively cultivated areas. Accordingly, this research presents a workflow merging multi-date S1 smoothed data acquired at distinct LIA with a Gaussian processes regression (GPR) and a cross-validation (CV) strategy to estimate cropland LAI of irrigated winter wheat. The GPR-S1-LAI model was tested against in situ data of the 2020 winter wheat campaign in the irrigated valley of Colorador river, South of Buenos Aires Province, Argentina. We achieved adequate validation results for LAI with RCV2 = 0.67 and RMSECV = 0.88 m2 m−2. The trained model was further applied to a series of S1 stacked images, generating temporal LAI maps that well reflect the crop growth cycle. The robustness of the retrieval workflow is supported by the associated uncertainties along with the obtained maps. We found that processing S1 smoothed imagery with distinct acquisition geometries permits accurate radar-based LAI modeling throughout large irrigated areas and in consequence can support agricultural management practices in cloud-prone agri-environments.

The objective of this work was to study the agronomic effects of the application of agri-food composts in almond trees (Prunus dulcis L.) cultivated in two different areas with different almond varieties (cv. Guara and cv. Ferraduel), with both in organic farming conditions throughout two cropping cycles. To reach this objective, almond production and quality issues (seed production, kernel yield, nutrient contents and kernel quality), as well as several physico-chemical and biological properties of the amended soils at the beginning and at the end of each campaign were studied. The four composts used (C1, C2, C3 and C4) were elaborated mainly using exhausted grape marc (EGM) and other wastes (waste from orange juice production, OW; waste from tomato soup production, TW; cattle manure, CM; and sheep manure, SM). Two treatments were used as control treatments, one based on sheep manure and another without any amendment. The composts used produced similar results in kernel yield and production compared to the traditional treatment (sheep manure). However, the thickness of the kernel was higher in the treatments using composts with exhausted grape marc and sheep manure or tomato soup waste. In relation to the almond quality, few differences related to the effect of treatments were observed, except for the content of proteins, sucrose, some fatty acids and vegetal sterols.

Organic solid wastes are rarely considered when planning for rural production in Argentina. Onion production in the low valley of Río Colorado (Buenos Aires) generates between 12,000 and 20,000 Mg year−1 of vegetal wastes (i.e., leaves, stems, skins, roots) from harvesting, cleaning and classification of bulbs, causing many problems with their management. The aim of this work is to study the effect of different doses of onion residue-bovine manure compost and onion residue-bovine manure compost tea on the soil physicochemical properties, microbial activity and agroecological onion production in sandy soil. Results showed that the highest dose of compost caused the highest effects on soil pH, electrical conductivity and nutrient content. Soil enzymatic activities were already high in the soil before the compost was applied, which may have contributed to the small effect caused by any dose on soil activity. A significant positive effect on bulb weight and organic onion yield were found as a result of the amendment and growing season. In conclusion, agroecological production of onion with the addition of a 300 kg N ha−1 compost and compost tea guarantee yields comparable to those of conventional fertilization, as occurred during the two growing seasons of this study.

Composted manure is the greatest nitrogen (N) source in organic agriculture, where the use of chemical fertilizers, except the use of rock phosphate as P source, is not allowed. The aim of this study was to evaluate the effect of the soil type and compost characteristics on the potential rates of mineralization and on the kinetics of the nitrogen (N), phosphorus (P), and carbon (C) release patterns. For this, an aerobic incubation study was conducted over the course of 119 days at 25 °C using two different composts as amendments: a compost from biosolids and wood shavings (CRUB), and a compost from poultry manure with wheat straw (CSP). The composts were incorporated into two different soils of contrasting texture, sandy loam (S1) and silty clay loam (S2), at the dose of 160 kg N ha−1. Samples were collected eight times during the incubation period. The N and C dynamics were studied separately according to the different soil type. In both soils, a predominance of the nitrification process immediately after compost application was observed, showing a higher mineralization in the sandy loam soil, this trend being followed by a decrease and even an immobilization process, associated with stable organic materials such as compost. Moreover, both composts presented high contents of available P, but without exceeding 50 mg P kg−1, due to the slow release from the stable organic P fractions present in compost. The results obtained showed that despite the initial mineralization, both composts showed a significant period of N immobilization after their application into the pampean soils, which makes it necessary to anticipate their incorporation to avoid this lack period for crops. Furthermore, the application of these composts to the pampean soils implied an incorporation of available P, but with a slow release that avoided overfertilization, but also reducing N:P ratio and producing a relative deficit of N. Therefore, the results obtained suggested that it is necessary to study nutrient mineralization processes of the amendments prior to their use, according to the edaphoclimatic condition of each crop, in order to predict the release dynamics on soils and the fertilization potential to minimize potential environmental impacts.