Biochar + Organic fertilizer promotes Yield & Quality of Red Pitaya
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Highlights
Co-application of biochar and organic fertilizer is more advantageous.
Soil properties, red pitaya yield and qualities were elevated.
We suggest that farmers can apply 3% biochar +45 t ha−1 organic fertilizer.
Biochar with high application rates exerted a negative effect on profit.
Abstract
This study evaluated the combined impact of biochar and organic fertilizer on the soil properties, yield and quality of red pitaya (S. polyrhizus). A two-year (2019 and 2020) field experiment was conducted to study the effects of 3 rates of biochar (with carbon fertilizer ratios of 0%, 3%, and 6% w/w) combined with 3 levels of organic fertilizer (22.5, 45, and 90 t ha−1) on soil properties, along with red pitaya yield and quality. The results showed that soil pH, total organic carbon, available nutrients (N, P, and K), the yield and qualities (reduced sugar, soluble protein, and soluble solid) of red pitaya increased with the application of organic fertilizer compared with no application of biochar and organic fertilizer (CK treatment), but the combined application of biochar and organic fertilizer was more effective than their sole application. Furthermore, a medium dose of organic fertilizer combined with 3% biochar (C3F2 treatment) and a high dose of organic fertilizer combined with 3% biochar (C3F3 treatment) had the highest yields of red pitaya in 2019 and 2020. However, an application of 6% biochar with a low dose of organic fertilizer treatment (C6F1) had the highest profit in 2020, not the C3F3 treatment. The highest profits were observed in the C3F2 (71.0 × 103 RMB·t−1) and C6F1 (51.2 × 103 RMB·t−1) treatments. From the point of view of red pitaya yield and economic benefits, 3% biochar +45 t ha−1 organic fertilizer was the recommended combination that showed the best synergistic effect.
Introduction
Biochar has multifunctional value, and biochars, as additives and catalysts, can help to promote microbial population growth . Recently, biochar, characterized by a large surface area, abundant nutrient elements and high cation exchange capacity , has been suggested as a good option to improve soil quality for crop growth. Biochar is a kind of stable carbon-rich charcoal, which is formed by the pyrolysis of biomass materials under oxygen-limited or anoxic conditions .
Most research has indicated that a soil amendment with a positive effect, known as biochar, can support to promote crop growth and improve crop yields by improving soil and water conditions ), increasing soil available nutrients and organic matter , and improving soil properties . Biochar has been reported to enhance the utilization rate of chemical fertilizer, nutrient uptake , and soil carbon sequestration , and to promote nutrient recycling for soil microbial communities . The application of biochar acts not only as a soil amendment but also as an organic fertilizer, especially in soils with low fertility and in degraded lands.
Therefore, biochar is a versatile material to promote plant growth and improve soil properties but cannot serve as a long-term and sufficient nutrient source for plants. Hence, to retain the sustainable development of agriculture, organic fertilizer can be used as an effective substitute for chemical fertilizer because of its sustainable release of nutrients.
Organic fertilizer can improve plant growth by slowly releasing available micro- and macro-nutrients , as well as additional-value substances , thus either directly or indirectly protecting and updating soil quality. Schulz and Glaser (2012) reported that mineralized organic fertilizer could provide more sustainable nitrogen (N) and phosphorus (P) for plant growth. Moreover, organic fertilizer improved microbial reproduction, soil properties, and biological activity and maintained fertilizer efficiency . Currently, studies addressing the agronomic benefits of biochar application have progressed considerably to field trials. Many studies have demonstrated that the combination of fertilizer together with biochar could be a promising approach for nutrient immobilization, release, and plant uptake while enhancing plant growth and improving soil quality. For instance, the benefits of biochar and organic fertilizer application may increase the uptake of P and the yield of crops compared with a blank control by raising soil pH, attracting beneficial microbes, and retaining nutrients or increasing yield and plant nutrition compared with pure fertilizers without biochar . It has also been found that the abundance of microbial biomass and total N content in the rhizosphere of soybean in treatments applying biochar and fertilizer were better than those of fertilizer treatment alone in infertile soil . The effect of soil amendment with biochar on soil fertility and plant growth has been studied intensively . However, there is limited information on the combination of biochar and organic fertilizer to improve dry red soil.
Red pitaya is a tropical and subtropical fruit rich in vitamin C, reduced sugar, anthocyanins, soluble protein, glucose, and a variety of minerals. In addition, red pitaya provides remarkable economic benefits to local farmers, while the plant uptake of nutrients is restricted under the high silt of dry red soil. To meet the nutrient demands of the growth and production of red pitaya (S. polyrhizus) in recent years, a large dose of organic fertilizer (45 t ha−1) was required. Although a large number of field experiments have been conducted to asses the effects of biochar combined with fertilizer on soil properties and crop growth, the impact of the co-application of biochar and organic fertilizer on plant (in particular red pitaya) is still not well understood. In addition, three-year studies did not recommend adding biochar to replant apple orchards, especially in fertile soils, because biochar and compost may only be useful during the early growth stages, and the positive effects of biochar could not be fully reflected (Safaei et al., 2019). Therefore, in dry red soils with low fertility, we hypothesized that biochar and organic fertilizer amended would have positive effects on improving soil properties and promoting fruit yields and quality.
Therefore, we conducted a field experiment in dry red soil for two years during 2019 and 2020 with the following objectives: (i) to explore the effects of biochar and organic fertilizer addition on soil pH, total organic carbon (TOC), available N, available P, and available potassium (K) contents under farm conditions in typical dry red soil; (ii) to investigate the response of biochar combined with organic fertilizer on the red pitaya yield and quality; and (iii) to propose an applicable biochar and organic fertilizer addition strategy for enhancing red pitaya yield and profit in the study area.
Effects on soil properties
Two years after biochar and organic fertilizer treated, a significant interactional effect of biochar and organic fertilizer on soil properties was recorded (p < 0.05). It is noteworthy that the red pitaya was adapted to grow in slightly acidic to neutral soil (6.0–7.5). In this study, the initial pH of the soil was 5.57 (Table 1), and the significant increase in soil pH after planting was related to the level of use of biochar and organic fertilizer. Soil pH values increased as the doses of
Conclusion
The 2-year field experiments provided data for the influence of biochar and organic fertilizer on soil properties, red pitaya yield and quality, and income analysis. The results confirmed the potential of the co-application of biochar and organic fertilizer to achieve increases in soil pH, TOC, available N, available P, and available K contents in dry red soil. This confirmed that the improved yield and qualities of red pitaya were attributed to enhanced soil properties.
Source: https://www.sciencedirect.com/science/article/abs/pii/S0045653522001084
