Remote estimation of nitrogen and chlorophyll contents in maize at leaf and canopy levels

Abstract

In the present study, the quality of aerated and non-aerated compost teas and bioslurry as bio-fertilizers and its application on two plant species in different substrates were tested. Compost tea brewed from a mixture residues compost presented higher nutrient content than that brewed from grape marc composted. Aeration, with shorter extraction time, resulted in higher pH, but in general with lower nutrient concentration, while bioslurry, presented higher nitrogen content. No pathogen and toxic effects were detected in the bio-products. Finally, Bio-products were evaluated in ornamental plant species: Petunia hibrida and Impatiens walleriana , where compost teas and bioslurry presented highly variable properties and effects on plant growth, depending on the substrate and species used. While in sand no signi cant effect on plant biomass and pigments were observed, in compost and commercial substrate bioslurry presented values similar to the traditional fertilizer. Compost tea presented variable results with no differences between aerated and non-aerated, both increasing carotenoids in I. walleriana in sand. We conclude that aeration showed no differences in compost tea quality, whilst bioslurry demonstrated to increase plant biomass at similar values to traditional fertilizer. Our results demonstrated that alternative products are an e cient, safe, ecological, and economical alternative to traditional products. Highlights Non-aerated and longer brewing time enhances nutrient extraction. Compost achieved from diverse residues results in a nutrient richer byproducts. Bioslurry increased plant biomass at values similar to commercial fertilizer. The Bio-products effect was highly dependent on plant species and substrate used. It is necessary, therefore, to develop and implement the use of alternative products that minimize agricultural impacts. Bio-products are by-products from biological sources, that provide nutrients, and bene cial microorganisms that promote plant growth. Usually, bio-products are derived from organic wastes that exploit the presence of nutrients and bene c microorganisms, while the residues are treated and reduced. Composting is an alternative that allows to relatively safe treat a high quantity of organic waste, while a high-value product is generated [4, 5]. It is an aerobic biological process by which biodegradable organic materials are transformed into a homogeneous product assimilable by plants [6, 7, 8]. The ltered suspensions of compost in water, denominated compost teas, are able to extract soluble nutrients and bene c microorganisms to be used as plants fertilizer or as biopesticide [9, 10]. It may be obtained from two main processes: aerated and non-aerated. The rst one is usually associated to reduced elaboration time, but it is necessary the use of aerators and energy sources available, while in non-aerated, no energy and equipment are needed, but the time required may be extended. Despite non-aerated compost tea is usually indicated as phytotoxic and to bene ts pathogen growth, no r...

Estimating foliar nitrogen in Eucalyptus using vegetation indexes

“…Clev- ers and obtained good results using this index to estimate N concentration in potatoes, as well as Schlemmer et al (2013) in maize.…”

“…Nitrogen is associated with several important proteins in the photosynthetic process (Moran et al, 2000;Ollinger, 2011). Therefore, it has a direct relationship with chlorophyll (Schlemmer et al, 2013) and biomass production (Miller, 1984;Smethurst et al, 2004).…”

“…Based on the close relationship between chlorophyll and N, these VIs have been used to estimate N concentration in rice (Tian et al, 2011;Yao et al, 2013), maize (Schlemmer et al, 2013), grasses and potatoes (Clevers and Gitelson, 2013). However, the use of such indexes to estimate N concentration in Eucalyptus is rare in the literature.…”

Predicting macronutrient concentrations from loblolly pine leaf reflectance across local and regional scales

“…These indices were selected due to Table 1. Common vegetation reflectance indices and their formulas calculated for correlation with and prediction of foliar macronutrient concentrations (Gökkaya et al 2014;Schlemmer et al 2013;Stagakis et al 2010;Ustin et al 2009). "R" denotes reflectance and "D" the derivative for a given wavelength (nm).…”

Estimating Biomass and Nitrogen Amount of Barley and Grass Using UAV and Aircraft Based Spectral and Photogrammetric 3D Features

“…Existing studies have focused more on biomass estimation than on nitrogen content estimation. Especially the studies on the use of hyperspectral data in nitrogen estimation have commonly used terrestrial approaches (e.g., [52][53][54]). …”