Biochar Improves Soil-Tomato Plant, Tomato Production, and Economic Benefits under Reduced Nitrogen Application in Northwestern China

Abstract

The tomato is an important economic crop that is a main ingredient of some prepared food as well as a focus of the agricultural industry. Optimizing nitrogen (N) fertilizers is essential for sustainable agricultural development, while the excessive use of N fertilizers leads to environmental and food production problems. As a soil amendment, biochar has been widely used to improve soil quality and crop yield. However, little information is available on the effects of biochar and N fertilizer reduction on tomato plant, soil characteristics in tomato cultivation and tomato production. In this study, a greenhouse experiment was carried out in Yangling, Shaanxi province, China, including four biochar levels (0, 30, 50, and 70 t ha−1) under drip irrigation and four N application rates (170, 190, 210, and 250 kg ha−1). The results showed that adding too much biochar (e.g., 70 t ha−1) and reducing N fertilizer too far (e.g., by 32%) will not lead to satisfactory results in terms of tomato growth, tomato yield and quality, and economic benefits. Biochar addition could significantly enhance microbial abundance, enzyme activity, and tomato growth compared with non‒biochar treatments when reducing the amount of applied N fertilizer by 16% or 24% (N2 and N3). From the perspectives of tomato yield, tomato quality (sugar‒acid ratio and vitamin C (VC) content), and economic benefits, optimal application rate of biochar and N fertilizer based on the silty clay loam soil of northwest China under drip irrigation is proposed, respectively. The proposal is based on both multidimensional nonlinear regression models and a comparison with experimental treatments. For example, biochar addition at 50 t ha−1 and reducing N fertilizer by 24% achieved the greatest tomato yield. Compared with non-biochar treatment under the corresponding N fertilizer level, soil enzyme activity (urease, phosphatase, and catalase), microbial abundance (bacteria, fungi, and actinomycetes), leaf gas exchange parameters (gs, Pn, and Tr), and biomass increased on average by 88.76%, 7.49%, 43.23%, and 39.67%, respectively. Based on a comprehensive consideration of tomato yield, VC content, sugar‒acid ratio, and economic benefits, 35 t ha−1 biochar and 200 kg ha−1 N fertilizer is the recommended combination of biochar and nitrogen fertilizer for local farmers.

Physicochemical Changes in Loam Soils Amended with Bamboo Biochar and Their Influence in Tomato Production Yield

“…This investigation revealed that the addition of biochar enhanced crop production by improving soil physical and chemical properties [47], with positive and negative effects depending on soil texture, which agrees with Sohi et al [15]. Other studies, carried out in tomato crops, have also reported a relationship of crop yield to water and nutrient retention capabilities [5,6], soil aeration [8], and pH enhancement [48].…”

Effects of Biochar on Biointensive Horticultural Crops and Its Economic Viability in the Mediterranean Climate

“…Most studies were performed in tropical and temperate zones of America, Asia, and Oceania, with no shortage of rain and even with a risk of flooding. Nevertheless, Guo et al reported yield improvements of up to 60% when using application rates of 30, 50, and 70 t/ha, fundamentally due to biochar interference in the fixation of supplemented nutrients and nutrient exchange in the soil-plant system [55]. In these temperate zones, other authors have reported results ranging from no improvement to slight improvements of 10% in tomato yield [56,57].…”

Biochar: An emerging recipe for designing sustainable horticulture under climate change scenarios

“…Moreover, the addition or application of organic or inorganic solutes may alter plant water relations. For example, Guo et al. (2021a) reported improved root hydraulic conductance and leaf water potential (Ψl) in water-stressed tomato grown on a sandy loam soil incorporated with miscanthus straw BC.…”