The effects of soil amendments and mulch on emergence, pod development and yield of bambara groundnut (Vigna subterranea L.) in a hard-setting soil

Review of existing knowledge on soil crusting in South Africa

“…She concluded that all gave good results and that any could be used to assess the crust strength of soils. Materechera et al (2007) and Materechera (2009) measured penetration resistance to a depth of 10 cm by means of a handoperated soil cone penetrometer. Manyevere et al (2015) did not determine crust strength, but only crust thickness, which they found to vary between 1 and 10 mm (0.1 to 1 cm) in different soils.…”

“…This region included what is now the eastern half of the North West Province, the northern Free State, Gauteng and the Highveld of Mpumalanga. Crusting was found to be a widespread problem on red sandy soils of the Hutton form in parts of the North West Province (Molope, 1992;Materechera et al, 2007). The senior author similarly found severe crusting in a red sandy soil near Radium, south of Bela-Bela in the south of Limpopo.…”

“…It has been mentioned that in the 1950s Sellschop identified this as a major problem in the growing of groundnuts in the then Highveld region. Materechera et al (2007) found that seedling emergence of Bambara groundnut (Vignasubterranea L.) was inhibited by soil crusting in sandy soils in North West Province, giving only 64.8% emergence compared with 87.9% where the crust was alleviated. Massingue (2002) showed that seedling emergence decreased with increasing crust strength above a critical value.…”

“…In a field experiment with Bambara groundnut on a crusting soil, Materechera et al (2007) found significant alleviation of the impacts of crusting by application of 3 t.ha -1 straw mulch.…”

“…For podding, mulch gave the best results, but not statistically significant better than gypsum or manure. (Note that all these interpretations are based on recalculated two-year averages by the senior author from the year values given in Table 1of the Materechera et al (2007) paper and not on the two-year averages given in the table .) Massingue (2002) found that increasing mulch applications from 0 to 6 t.ha -1 "considerably" improved the emergence of seedlings in a crusting soil. She found that more than 70% soil cover by crop residues is highly effective in reducing crust strength.…”