Effects of biochar and manure on soil properties and growth of Casuarina equisetifolia seedlings at the coastal region of Kenya

This study investigated the effects of biochar and manure applied singly or together on soil biochemical properties, Casuarina equisetifolia seedling growth and seedling quality. Therefore, a nursery experiment consisting of Prosopis juliflora biochar and cattle manure treatments at 0% (control), 10% biochar, 20% biochar, 10% manure, 10% biochar + 10% manure, and 20% biochar + 10% manure was conducted. Generally, biochar containing treatments recorded higher P concentrations; where the combination of 20% biochar and 10% manure gave the highest phosphorus concentration, which was 137.3% above the control. Nitrate concentrations were higher in manure treatments than the control by 122.9%. As a result of C. equisetifolia’s ability to fix nitrogen, nitrates concentration in the control increased from 0.016 ppm at the onset of the experiment to 2.18 ppm at the end the experiment. There was also a general increase in pH with biochar and manure application. Seedlings treated with 10% manure recorded the highest collar diameter and height which was 36.4 and 27.4% above the control respectively while treatments with biochar alone recorded the lowest seedling collar diameters. Seedling quality as observed using the shoot/root ratio showed that sole biochar treatments had the recommended range of <3:1. These results suggest that the use of biochar and manure enhances nitrogen and phosphorus availability which are crucial for production of seedlings that grow significantly faster than seedlings raised from forest soil only. Key words: Biochar, manure, Casuarina, seedling quality, soil properties.