No significant influence of biochar and manure application on nitrogen fate and sequestration by tomato and garlic crops: A field experiment in California, USA
Suduan Gao, Yinghua Duan, Dong Wang, Thomas A. Turini
Abstract
Abstract Organic soil amendments can improve soil health but their role in improving N management has not been well quantified. The objectives of this research were to evaluate the influence of biochar and manure compost application on crop yield, N uptake, changes in soil and environmental losses and to use the information to assess the N requirement and project fertilization needs. A field experiment was conducted in California, USA, with processing tomato ( Lycopersicon esculentum Mill.) grown first, followed by garlic ( Allium sativum ). The soil was a sandy loam with a pH of 7.2 and CEC of 9.1 cmol(+) kg −1 . Treatments included two biochar products, derived from almond shell or softwood feedstocks, applied at 20 or 40 tonnes (t) ha −1 , dairy manure compost at 20 t ha −1 , combinations of the manure and the biochar (each at 20 t ha −1 ), and a control. Although biochar and manure applications improved the surface soil organic C and total N content, no significant effects on crop yield, biomass and N uptake, as well as ammonia volatilization and leaching loss, were observed. The amount of N sequestered by plants ranged from 3.2 to 3.8 and 9.9 to 10.0 kg N Mg −1 to produce fresh tomato fruits and garlic bulbs, respectively. However, about half of the N for tomato and 93% for garlic plants were removed from soil by harvesting. The N sequestered per unit biomass (or yield) production appears a stable parameter, which can be used to reliably project fertilization needs that target high NUE and minimal loss to the environment.