Impact of Specific Leaf Extracts on Soil pH and Beta-Carotene in Amaranthus in Kiambu County, Kenya

Abstract

Amaranthus (Amaranthus spp.) leaves are a good source of nutrients including vitamins antioxidants and dietary minerals including calcium, iron, and potassium. Soil pH is a very important chemical property of the soil, as it dictates the availability of plant nutrients. Acidic soils reduce availability of plant nutrients and hinder growth. This is corrected by adding lime which is expensive, does not add nutrients and requires re-application. The objective of this study was to evaluate the effects of leaf extracts from selected tree leaves on soil acidity and beta-carotene levels of amaranthus. Plant leaves that were tested were Turril (Vitex keniensis) Mexican sunflower (Tithonia diversifolia) and Indian nettle (Plectranthus barbatus). The experiment setup was in a 2 x 7 factorial arrangement in a randomized complete block design(RCBDreplicated three timesThe treatments were; the three leaves extracts, lime, farm yard manure, inorganic fertilizer and control.. Leaves were dried,ground and soaked in distilledwater for sixty days as pH was monitored and the resulting  extract was added to soil for amanthus grown with plant extracts. Data on plant height, leaf area, number of leaves, fresh weight and dry weight and levels of beta carotene levels were collected. AOAC method was used for analysis of beta carotene. All data was subjected to analysis of variance (ANOVA) at 5% level of significance using SAS and least significant difference (LSD) for means separation. The results showed that leaf extracts significantly reduced soil acidity to above (6) while inorganic fertilizer increased the acidity (pH5.9) to (5.3) on all growing conditions while humus increased acidity during rainy and irrigation conditions. On beta carotene levels, Farmyard Manure had the highest levels(51.1µg) followed by the leaf extracts with extract 3-Plectras barbatus having higher levels. Control had the lowest levels of beta carotene followed by inorganic fertilizer and lime.These results suggest that farmers should be encouraged to grow vegetables using farmyard manure and leaf extracts to increase antioxidant levels and reduce soil acidity.They should also be encouraged to grow more of trees and shrubs studied to increase forest cover.