Municipal solid waste compost use can improve crop barley production and enhance soil chemical fertility

Abstract

The study aims to point out the effect of municipal solid waste compost (MSWC) and traditional mineral fertilizers use, on rainfed forage barley herbage and grain production, nutritive value, and on soil chemical characteristics. During a three-year field trial, the MSWC treatments were COM1, 20 Mg ha−1 (DM) applied each year; COM2, 20 Mg ha−1 applied only the first year. The mineral fertilization was MIN50 (50 kg ha−1 of N + 46 kg ha−1 of P2O5), and MIN100 (100 kg ha−1 of N + 92 kg ha−1 of P2O5), applied each year. Fertilization treatments were compared with unfertilized control (COM0 and MIN0). Two years out of three COM1 showed a significant higher barley herbage dry matter (HDM) production and CP, when compared to COM0. COM1 in one year increased grain yield (YLD) whereas increased CP all years and decreased starch grain content two years out of three. MSWC strongly increased levels of sodium (Na) in herbage and grain. Mineral fertilizers levels significantly increased HDM production and YLD and their CP content compared to MIN0. Moreover, it lightly decreased herbage NDF, ADF, WSC and Total phenols content, raising in vitro dry matter digestibility (IVDMD). In soil, after three years of fertilization, COM1 increased SOC (Soil Organic Carbon), Total N, available P, exchangeable K and Mg content, but also exchangeable sodium percentage (ESP) and electrical conductivity (EC), showing higher values than COM2 and COM0. Mineral fertilization influenced only the available P soil level, increasing the content compared to MIN0. This paper pointed out that mineral fertilizers had clear short-term effects on the barley growth, yield, and nutritional value, but did not contribute to soil long-term fertility improvement. MSWC increased barley growth and yield reaching similar values obtained with mineral fertilizers. Above all, MSWC showed capability to improve soil fertility mainly in terms of organic matter and macronutrients and its use is consistent with the recent EU regulation on organic fertilizer productions (2018/84) that aims to “maintaining the long-term fertility of soils”.