Chemical and Biological Technologies in Agriculture · 2021
Biological and synthetic approaches to inhibiting nitrification in non-tilled Mediterranean soils
Bozal-Leorri, A., Corrochano-Monsalve, M., Arregui, L. M., Aparicio-Tejo, P. M., González-Murua, C.
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Biological and synthetic approaches to inhibiting nitrificat…
Abstract
Background The increasing demand for food production has led to a tenfold increase in nitrogen (N) fertilizer use since the Green Revolution. Nowadays, agricultural soils have been turned into high-nitrifying environments that increase N pollution. To decrease N losses, synthetic nitrification inhibitors (SNIs) such as 3,4-dimethylpyrazole phosphate (DMPP) have been developed. However, SNIs are not widely adopted by farmers due to their biologically limited stability and soil mobility. On the other hand, allelopathic substances from root exudates from crops such as sorghum are known for their activity as biological nitrification inhibitors (BNIs). These substances are released directly into the rhizosphere. Nevertheless, BNI exudation could be modified or even suppressed if crop development is affected. In this work, we compare the performance of biological (sorghum crop) and synthetic (DMPP) nitrification inhibitors in field conditions. Results Sorghum crop BNIs and DMPP prevented an increase in the abundance of ammonia-oxidizing bacteria (AOB) without affecting the total bacterial abundance. Both nitrification inhibitors maintained similar soil NH 4 + content, but at 30 days post-fertilization (DPF), the sorghum BNIs resulted in higher soil NO 3 − content than DMPP. Even so, these inhibitors managed to reduce 64% and 96%, respectively, of the NO 3 − -N/NH 4 + -N ratio compared to the control treatment. Similar to soil mineral N, there were no differences in leaf δ 15 N values between the two nitrification inhibitors, yet at 30 DPF, δ 15 N values from sorghum BNI were more positive than those of DMPP. N 2 O emissions from DMPP-treated soil were low throughout the experiment. Nevertheless, while sorghum BNIs also maintained low N 2 O emissions, they were associated with a substantial N 2 O emission peak at 3 DPF that lasted until 7 DPF. Conclusions Our results indicate that while sorghum root exudates can reduce nitrification in field soil, even at the same efficiency as DMPP for a certain amount of time, they are not able to prevent the N pollution derived from N fertilization as DMPP does during the entire experiment. Graphic Abstract
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Background The increasing demand for food production has led to a tenfold increase in nitrogen (N) fertilizer use since the Green Revolution. Nowadays, agricultural soils have been turned into high-nitrifying environments that increase N pollution. To decrease N losses, synthetic nitrification inhibitors (SNIs) such as 3,4-dimethylpyrazole phosphate (DMPP) have been developed. However, SNIs are not widely adopted by farmers due to their biologically limited stability and soil mobility. On the other hand, allelopathic substances from root exudates from crops such as sorghum are known for their activity as biological nitrification inhibitors (BNIs). These substances are released directly into the rhizosphere. Nevertheless, BNI exudation could be modified or even suppressed if crop development is affected. In this work, we compare the performance of biological (sorghum crop) and synthetic (DMPP) nitrification inhibitors in field conditions. Results Sorghum crop BNIs and DMPP prevented an increase in the abundance of ammonia-oxidizing bacteria (AOB) without affecting the total bacterial abundance. Both nitrification inhibitors maintained similar soil NH 4 + content, but at 30 days post-fertilization (DPF), the sorghum BNIs resulted in higher soil NO 3 − content than DMPP. Even so, these inhibitors managed to reduce 64% and 96%, respectively, of the NO 3 − -N/NH 4 + -N ratio compared to the control treatment. Similar to soil mineral N, there were no differences in leaf δ 15 N values between the two nitrification inhibitors, yet at 30 DPF, δ 15 N values from sorghum BNI were more positive than those of DMPP. N 2 O emissions from DMPP-treated soil were low throughout the experiment. Nevertheless, while sorghum BNIs also maintained low N 2 O emissions, they were associated with a substantial N 2 O emission peak at 3 DPF that lasted until 7 DPF. Conclusions Our results indicate that while sorghum root exudates can reduce nitrification in field soil, even at the same efficiency as DMPP for a certain amount of time, they are not able to prevent the N pollution derived from N fertilization as DMPP does during the entire experiment. Graphic Abstract
Background The increasing demand for food production has led to a tenfold increase in nitrogen (N) fertilizer use since the Green Revolution. Nowadays, agricultural soils have been turned into high-nitrifying environments that increase N pollution. To decrease N losses, synthetic nitrification inhibitors (SNIs) such as 3,4-dimethylpyrazole phosphate (DMPP) have been developed. However, SNIs are not widely adopted by farmers due to their biologically limited stability and soil mobility. On the other hand, allelopathic substances from root exudates from crops such as sorghum are known for their activity as biological nitrification inhibitors (BNIs). These substances are released directly into the rhizosphere. Nevertheless, BNI exudation could be modified or even suppressed if crop development is affected. In this work, we compare the performance of biological (sorghum crop) and synthetic (DMPP) nitrification inhibitors in field conditions. Results Sorghum crop BNIs and DMPP prevented an increase in the abundance of ammonia-oxidizing bacteria (AOB) without affecting the total bacterial abundance. Both nitrification inhibitors maintained similar soil NH 4 + content, but at 30 days post-fertilization (DPF), the sorghum BNIs resulted in higher soil NO 3 − content than DMPP. Even so, these inhibitors managed to reduce 64% and 96%, respectively, of the NO 3 − -N/NH 4 + -N ratio compared to the control treatment. Similar to soil mineral N, there were no differences in leaf δ 15 N values between the two nitrification inhibitors, yet at 30 DPF, δ 15 N values from sorghum BNI were more positive than those of DMPP. N 2 O emissions from DMPP-treated soil were low throughout the experiment. Nevertheless, while sorghum BNIs also maintained low N 2 O emissions, they were associated with a substantial N 2 O emission peak at 3 DPF that lasted until 7 DPF. Conclusions Our results indicate that while sorghum root exudates can reduce nitrification in field soil, even at the same efficiency as DMPP for a certain amount of time, they are not able to prevent the N pollution derived from N fertilization as DMPP does during the entire experiment. Graphic Abstract
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