Soil Quality as a Key Factor in Producing Vegetables for Home Consumption—A Case Study of Urban Allotments in Gorzów Wielkopolski (Poland)

Abstract

The aim of the study was to analyse the quality of soil in urban allotment gardens in the context of the production of home-grown vegetables. The study was conducted on six allotment gardens (31 individual plots) in Gorzów Wielkopolski, a medium-sized Polish city with an average level of industrialisation. The following soil characteristics were analysed: pH, electric conductivity, organic matter, organic carbon, humus, total nitrogen, C:N ratio, NH4+-N, NO3-N−, P, K, Ca, Mg, SO4−-S, Cl, Na, Fe, Cu, Zn, Mn, Ni, Cr, Cd, Pb. The analyses showed that the soils were abundant in necessary nutrients for vegetable growing. They had high content of calcium, magnesium, and phosphorus. However, the soil pH in areas of vegetable cropping was too high. The content of toxic heavy metals—cadmium (0.22–0.59 mg∙kg−1 d.m.) and lead (3.46–16.89 mg∙kg−1 d.m.)—was within the acceptable limits. Nevertheless, the chemical analysis of carrots used as test vegetables showed that the permissible limits of cadmium and lead content in their roots were exceeded. The excessive uptake of these toxic metals can be reduced by lowering the soil pH and applying organic carbon to the soil.

Methodological Approaches and Literature Analysis in the Study of Soil Carbon in Urban Green Spaces: A Systematic Review

“…Their soil carbon data provide carbon information, despite being the central theme of the research. For example, studies that focused on soil properties [22,29,[62][63][64][65][66][67][68][69][70][71][72][73][74], ecosystem services [2,19,31,43,[75][76][77][78] or aspects such as urban sprawl and land use change [26,77,79,80].…”

“…As mentioned in the introduction, a predominant focus on soil carbon has been studied in the form of SOC [1,2,4,[16][17][18][19]21,22,[26][27][28][29]43,45,[48][49][50][51][52][54][55][56][57][58][59][60][61][62]65,67,[69][70][71][72]74,76,[80][81][82][83] and in the form of Total Carbon [25,50,51,63,65,66,68,73,75,[77]…”

“…In terms of the methodology, there majority of the articles reported in situ sampling in soils of urban green areas. Many of these studies were based solely on in situ measurements [1,2,16,18,21,22,29,43,49,[52][53][54]56,[58][59][60][61][62][63][64][65][66][67][68][70][71][72][73][74][75][76]78,80,81,83,85]. Some researchers complement this approach with other methods such as remote sensing imagery [4,26,27,57], open data [26,28,45,79,84], logarithmic modelling [17,31,48,50,…”

“…In the analyses carried out using in situ measurements, a discrepancy was found in the criteria used for soil sampling depth. While the prevailing trend was to focus on the upper 0-20 or 0-30 cm soil depth [1,4,18,27,28,31,49,54,[56][57][58][59]62,63,65,69,71,72,75,82,83], there were also studies that consider the superficial soil layers, specifically 0-5 cm [21,76], or 0-10 cm [22,29,43,53,64,68,70,85]. Furthermore, some studies even considered in situ sampling at soil depths greater than 50 cm [2,16,17,25,26,45,48,50,52,60,67,74,[78][79][80]84].…”

“…Other studies found focused on urban horticultural spaces, community gardens, and allotment gardens [16,17,27,28,31,71,82], cultivated farmland [31,48,77], residential gardens [21,43,63,69,74], urban grasslands [1,4,49,59,70,76], green roofs [84], shrublands [4], roadsides and road greenbelt [75; 69; 85; 43; 76; 28], educational areas, university campuses or experimental centers [2,28,31,43,50,69,76], infiltration and vegetated swales [83], car parks [84], construction sites [77], bare land [77], and even cemeteries [31]. Wetlands [48,52,63,77] and mangroves [79] were also considered.…”