Impact of applying composted biosolids on wheat growth and yield parameters on a calcimagnesic soil in a semi-arid region
A field trial in a semi-arid climate was carried out on wheat (Triticum aestivum var. Marchouch) growing on a calcimagnesic soil using compost applied at 42 T/ha during the three years of study, but in different ways: C1, C2 and C3. Over this period, the level of total Kjeldhal nitrogen (TKN) increased in the soil amended by high doses (C2 and C3, by about 33 and 50%) compared with steady low amendment (C1) and to both controls NF (soil without fertilisation) and MF (soil receiving mineral fertilization). Adding compost also led to a positive influence on cation exchange capacity (CEC) by increasing humic substance levels (HS) which doubled in plots C2 and C3 compared with both controls. In NF soil, the TKN, total organic carbon (TOC) and the pH of soil showed a clear negative correlation with the agronomic parameters. In the MF soil, most physico-chemical parameters correlated well with the agronomic parameters: input of mineral elements balancing export through harvest. In amended soil, especially in C3 plots, HS and CEC showed significant correlations with most agronomic parameters (P1: 69.1%) due to enhanced CEC and sequestration of available carbon in the form of stable humic structures.
Key words: Compost, wheat growth, calcimagnesic soil, semi-arid region.