Fertigation of humic substances improves yield and quality of broccoli and nutrient retention in a sandy soil

Abstract

There is lack of information available concerning the effect of humic substances (HS) applied via fertigation on plant growth in sandy soils. Therefore, a field experiment was carried out at El-Saff district (20 km southwest of Cairo), Egypt, to investigate the role of HS fertigation on water retention of a sandy soil, yield and quality of broccoli (Broccoli oleracea L.) as well as on soil nutrient concentration retained after harvest. The experiment consisted of six fertigation treatments (50%, 75%, and 100% of the recommended NPK-fertilizer rate for broccoli combined with and without HS application at 120 L ha -1 ) in a complete randomized block design with three replicates. Humic substances affected spatial water distribution and improved water retention in the root zone. Furthermore, application of HS increased total marketable yield and head diameter of broccoli as well as quality parameters (i.e., total soluble solids, protein, and vitamin C). Higher nutrient concentrations were found in the broccoli heads and concentrations of plant-available nutrients in soil after harvesting were also higher, indicating an improvement in soil fertility. In conclusion, HS fertigation can be judged as an interesting option to improve soil water and nutrient status leading to better plant growth.

Agronomic performance and soil chemical attributes in a banana tree orchard fertigated with humic substances1

“…Selim & Mosa (2012) recorded positive effects on N, P, K, Fe, Mn and Zn contents, in sandy soil cultivated with broccoli submitted to NPK drip fertigation with doses of humic substances. These authors used doses of 120 L ha -1 , which corresponded to 21.96 kg ha -1 (humic acids + fulvic acids), fractionated into only three applications, during the four-month experiment.…”

Fertigation of ‘BRS Princesa’ banana with humic substance and saponin-based plant extracts

“…The absence of effects on banana growth can be related to the response time of the soil to the application of HS, which acted as conditioners of soil chemical and physical quality, improving its capacity of ion exchange, availability of nutrients, and structure (Selim and Mosa, 2012;Coelho et al 2016), but without directly supplying nutrients, such as organic matter in less advanced stages of decomposition, so that their action on plant nutrition and growth is indirect and does not occur immediately. Therefore, their effects may take a longer time in comparison with fertilizers industrially produced for rapid incorporation of nutrients …”

“…Fertigation with humic substances (HS) can be an interesting option to improve soil water and nutrient status leading to better plant growth (Selim and Mosa, 2012).…”

“…There are reports about the mechanisms of action of HS on plants (Nardi et al, 2002;Façanha et al, 2002;Canellas et al, 2009;Canellas and Olivares, 2014;Nardi et al, 2016). Recent publication of research results involving commercial plantations is available in the literature (Ferrara andBrunetti, 2008, Hartz andBottoms, 2010;Lima et al, 2011;Selim and Mosa, 2012;Lodhi et al, 2013). However, information is still scarce for tropical fruit crops.…”

“…Humic substances are used in the agricultural sector as a soil conditioner, because they favor the ionic stability of the soil solution and can promote increments in the absorption of nutrients by plants and, indirectly, in growth and production rates (Arancon et al, 2006;Pinheiro et al, 2010;Selim and Mosa, 2012). The use of plant extracts as tools of alternative pest control (Hooks et al, 2010) may cause, indirectly, the maintenance or increment in banana yield due to the conservation of the root system and, consequently, in the capacity of the plant to absorb water and nutrients from the soil solution.…”