EFFECT OF DIAMETER AND LEVEL ADDITION BIOCHAR ON SOME SOIL CHEMICAL PROPERTIES AND BROCCOLI GROWTH

Abstract

A field experiment was conducted during the fall season of 2024 to study the effect of biochar application level and diameter on some soil chemical properties and some growth traits of broccoli plants. The study included two factors: the first was the application level (B1 and B2: 0.5 and 1%), and the second was the diameter (D1, D2, and D3: 0.5, 1, and 2 mm) of biochar. The experiment was designed according to a randomized complete block design (RCBD) with three replications, using sandy clay loam soil. Broccoli seedlings (cv. Jassmine F1) were transplanted on 1^st October 2024.

 Results indicated an increase in soil pH values, with treatment D1B2 recording the highest value (7.6), whereas D3B1 showed the lowest (7.26), compared to the control (7.18). Biochar addition also raised the values of electrical conductivity (EC), where D1B2 reached the highest value (2.66 dS m⁻¹), while D3B1 recorded the lowest 2.2 dS m⁻¹, compared to the control (1.93 dS m⁻¹). Adding biochar to the soil led to an increase in CEC values, as D1B2 achieving the highest value (20.39 cmol⁺ kg⁻¹), whereas D3B1 showed the lowest (19.25 cmol⁺ kg⁻¹), compared to the control (18.19 cmol⁺ kg⁻¹), on the other hand, sodium adsorption ratio (SAR) values decreased, as D3B1 recorded the lowest value (1.03 meq L⁻¹), while D2B2 recorded the highest (1.21 meq L⁻¹), compared to the control (1.65 meq L⁻¹). Furthermore, the effect of adding biochar to soil on some growth characteristics of broccoli plants was investigated where D1B2 produced the tallest plants, reaching 72.90 cm, while treatment D3B1 achieved the lowest value, reaching 64.40 cm. Treatment D1B2 achieved the highest number of leaves, reaching 30 leaves per plant^-1, while treatment D3B1 achieved the lowest value, reaching 27 leaves per plant^-1.