Use of almond shell and almond hull as substrates for sweet pepper cultivation. Effects on fruit yield and mineral content

Abstract

The use of almond by products as substrate in greenhouses for growing vegetables has a great economic interest. The objective of this work was to assess the use of two almond by-products (almond shell-AS and almond hull-AH), which had been previously conditioned without composting, as substrates for pepper (cv. Caprino F1) production and to study their effects on the yield, fruit size, and fruit mineral content. Physical, physico-chemical, and chemical characteristics of the almond by-products were determined both initially and during the pepper growing season. Initially, all values of the parameters studied -except sulfur and iron-differed significantly between the two substrates. During cultivation, the 18 substrate parameters and variables tested -except bulk density-exhibited significant variations with time for AS; the same occurred for AH, exceptions being pH, total nitrogen N t , N-NH 4 , bulk density, and manganese. The changes in both substrates for the K, N, and S concentrations were significant. The nutrient levels in AH were higher than for AS. The almond shell and almond hull substrates produced slight decreases in total fruit yield with respect to the control (0.79 and 3.22 for AS and AH, respectively), with a lesser decrease for AS, due to reductions in the number of fruits per plant rather than to reductions in individual fruit weight. The plants grown on the AS and AH substrates showed a decrease in total fruit yield, due to reductions in the number of fruits per plant rather than reductions in individual fruit weight.

Effect of almond shell addition to substrates in Phaseolus vulgaris L. (cv. Saxa) growth, and physiological and biochemical characteristics

“…When in non-saline stress conditions, green bean plants use NO 3 -N rather than NH 4 -N for synthesis of proteins, and, ultimately, for plant development and growth. Almond shell has been reported to contain both NO 3 -N and NH 4 -N (Valverde et al 2013), and the increase of plant and pod biomass recorded for AM could indicate that NO 3 -N from shells may have been available for plant absorption in higher concentration than in AS substrate, (although keeping in mind that mineral composition of the shell used in the present work was not known). The previous works show that high concentrations of NH 4 + led to a reduction of growth and yield when compared to the presence of NO 3 (Harada et al 1968).…”

“…Webb] with shell, in 2013, was above 2.9 million tonnes. The shell can represent as much as 70% of the weight, and indicates a large quantity of byproducts that is produced by this industry (Ledbetter 2008), being primarily made of cellulose, hemicellulose, and lignin (Valverde et al 2013). This large amount of material has no economically and straight-forward important use, being either incinerated or discarded or using more complex approaches, used as substrate for xylose production (Pou-Ilinas et al 1990), furfural (Quesada et al 2002), or cellulose, pentosans, and lignin (Martinez et al 1995b).…”

Increasing Sustainability of Growing Media Constituents and Stand-Alone Substrates in Soilless Culture Systems

“…These include untransformed waste stream materials, which are affordable and available in certain areas. Waste materials can include, e.g., rice hulls [112][113][114], almond shell waste [115][116][117], hazelnut husks [118][119][120], and paper waste [121]. The main disadvantage of using these materials in commercial soilless media is that they are not produced specifically for horticultural applications; they can therefore be highly inconsistent.…”

Cultivation of black soldier fly larvae on almond byproducts: impacts of aeration and moisture on larvae growth and composition

“…There have been several studies examining the use of byproducts as alternatives or supplements to livestock feed. These have included ethanol production from hull sugars, anaerobic digestion to biogas, and as a nutrient supplement in soil . Another potential use of byproducts is for the cultivation of insects .…”

“…These have included ethanol production from hull sugars, anaerobic digestion to biogas, and as a nutrient supplement in soil. [7][8][9][10] Another potential use of byproducts is for the cultivation of insects. 11 Interest in insect production has grown recently due to concerns regarding the sustainability of feed sources for fish and poultry.…”