Review of Large-Scale Biochar Field-Trials for Soil Amendment and the Observed Influences on Crop Yield Variations

Abstract

Increasing pressure on farming systems due to rapid urbanization and population growth has severely affected soil health and fertility. The need to meet the growing food demands has also led to unsustainable farming practices with the intensive application of chemical fertilizers and pesticides, resulting in significant greenhouse gas emissions. Biochar, a multifunctional carbon material, is being actively explored globally for simultaneously addressing the concerns related to improving soil fertility and mitigating climate change. Reviews on biochar, however, mainly confined to lab-scale studies analyze biochar production and its characteristics, its effects on soil fertility, and carbon sequestration. The present review addresses this gap by focusing on biochar field trials to enhance the current understanding of its actual impact on the field, w.r.t. agriculture and climate change. The review presents an overview of the effects of biochar application as observed in field studies on soil health (soil’s physical, chemical, and biological properties), crop productivity, and its potential role in carbon sequestration. General trends from this review indicate that biochar application provides higher benefits in soil properties and crop yield in degraded tropical soils vis-a-vis the temperate regions. The results also reveal diverse observations in soil health properties and crop yields with biochar amendment as different studies consider different crops, biochar feedstocks, and local climatic and soil conditions. Furthermore, it has been observed that the effects of biochar application in lab-scale studies with controlled environments are not always distinctly witnessed in corresponding field-based studies and the effects are not always synchronous across different regions. Hence, there is a need for more data, especially from well-designed long-term field trials, to converge and validate the results on the effectiveness of biochar on diverse soil types and agro-climatic zones to improve crop productivity and mitigate climate change.

Zeolites and Biochar Modulate Olive Fruit and Oil Polyphenolic Profile

“…This may be why there was no positive response to soil conditioners in the olive yield in a short-term assessment. These observations substantiate the requirement of long-term soil amendments application field trials to accurately analyse its effects on crop yield and soil quality [36]. The effects of soil treatments on the biometric variables of fruits obtained from the harvests of 2018 and 2019 are also shown in Table 3.…”

“…Applying zeolites and biochar had no significant effect on crop yield in both years. Similarly, a lack of a substantial impact on crop yield by the short-term use of zeolites and biochar was reported by some authors [34][35][36]. Haider [37] showed that biochar needs a certain degree of ageing in the soil to affect the crop yield positively.…”

“…Haider [ 37 ] showed that biochar needs a certain degree of ageing in the soil to affect the crop yield positively. It may be due to the slow development of an organic coating on the biochar surface after the aging in compost media, which enhances nutrient retention [ 36 ]. In turn, using natural zeolites in combination with chemical fertilizers may act as a slow-release fertilizer, allowing the gradual release of nutrients [ 18 ].…”

Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review

“…On the other hand, several field studies demonstrated that applying biochar to agricultural soil significantly reduced nitrate, potassium, phosphorous, magnesium, sodium, and calcium leaching (Vijay et al 2021 ). Li et al ( 2019a ) reported that tobacco stems were pyrolysed to produce biochar.…”

Phenotyping of Different Italian Durum Wheat Varieties in Early Growth Stage With the Addition of Pure or Digestate-Activated Biochars

“…It has been assessed that biochar carbon and nutrient contents depend on the organic material contained in the original biomass feedstock used for its production, while biochar surface chemical properties as well as pore size depend more on the pyrolysis temperature ( Lei and Zhang, 2013 ; Zhao et al, 2013 ). In addition, the effects of biochar application may vary between laboratory-scale and field-based studies and across different agroclimatic zones ( Vijay et al, 2021 ).…”