Initial biochar effects on plant productivity derive from N fertilizations

Background and aim\ud Biochar application to soil is widely claimed to increase plant productivity. However, the underlying mechanisms are still not conclusively described. Here, we aim to elucidate these mechanisms using stable isotope probing.\ud Methods\ud We conducted two experiments with uniquely double-labelled (15N and 13C) biochar and its feedstock (residue), applied separately at 15 Mg ha−1. Both experiments contained three treatments: biochar amendment (Biochar), unpyrolysed residue amendment (Residue) and a no addition control (Control). Experiment I was a 119 day pot experiment seeded with Lolium perenne. Experiment II was a 71 day incubation experiment without plants in which CO2 and N2O fluxes were measured.\ud Results\ud Both Biochar and Residue significantly increased aboveground productivity compared to Control (140% and 160%, respectively). Initial N immobilisation was stimulated in Residue, whereas not in Biochar. 13C–CO2 analysis confirmed that biochar was significantly more recalcitrant than residue. 15N analysis showed that 2% and 0.3% of grass N was derived from the amended material in Residue and Biochar, respectively.\ud Conclusions\ud Our results suggest that biochar-induced yield increases derive from a combination of reduced N immobilization and a moderate N fertilization effect. Although in the short term biochar might offer benefits compared to residue incorporation, it is unlikely that biochar yield gains will be sustainable for the decades to centuries that biochar C can be expected to reside in soil

Initial biochar effects on plant productivity derive from N fertilizations

Background and aim\ud Biochar application to soil is widely claimed to increase plant productivity. However, the underlying mechanisms are still not conclusively described. Here, we aim to elucidate these mechanisms using stable isotope probing.\ud Methods\ud We conducted two experiments with uniquely double-labelled (15N and 13C) biochar and its feedstock (residue), applied separately at 15 Mg ha−1. Both experiments contained three treatments: biochar amendment (Biochar), unpyrolysed residue amendment (Residue) and a no addition control (Control). Experiment I was a 119 day pot experiment seeded with Lolium perenne. Experiment II was a 71 day incubation experiment without plants in which CO2 and N2O fluxes were measured.\ud Results\ud Both Biochar and Residue significantly increased aboveground productivity compared to Control (140% and 160%, respectively). Initial N immobilisation was stimulated in Residue, whereas not in Biochar. 13C–CO2 analysis confirmed that biochar was significantly more recalcitrant than residue. 15N analysis showed that 2% and 0.3% of grass N was derived from the amended material in Residue and Biochar, respectively.\ud Conclusions\ud Our results suggest that biochar-induced yield increases derive from a combination of reduced N immobilization and a moderate N fertilization effect. Although in the short term biochar might offer benefits compared to residue incorporation, it is unlikely that biochar yield gains will be sustainable for the decades to centuries that biochar C can be expected to reside in soil

A higher protein intake at breakfast does not compromise total daily protein intake in older adults

Introduction: A protein intake of 25–30 g per meal is suggested to maximally stimulate muscle protein synthesis in older adults in order to prevent sarcopenia. Protein intake at breakfast is often low and therefore breakfast offers the potential for protein suppletion. Since protein is known for its satiating effects, we explored the association between the amount of protein intake at breakfast and total daily protein intake in older adults. Methods: Baseline protein intake was assessed by a 3-day dietary record in 507 community dwelling older adults of 55 years and older participating in lifestyle interventions at the Amsterdam Nutritional Assessment Center. Multiple linear regression analysis was used to examine the association between protein intake at breakfast (in g) and total daily protein intake (in g, and g/kg body weight), adjusted for energy intake (kcal/d), sex, age and BMI. Interactions were tested for sex, age and BMI but were not significant (p>0.80). Results: Mean age was 67.6 ± (SD) 7.3 years, 42% was female, and mean BMI was 30.0 ± 5.6 kg/m2. Total daily protein intake was 81 ± 24 g which equals 0.96 ± 0.3 g/kg and 17.6 ± 3.7 percent of total energy intake. Protein intake at breakfast was 14 ± 7 g. A 10 g higher protein intake at breakfast was associated with a 6.7 g (SE = 1.0; P<0.001) and a 0.06 g/kg (SE = 0.01; P<0.001) higher total daily protein intake after adjustment for confounders. Key conclusions: A higher protein intake at breakfast does not compromise total daily protein intake in community dwelling older adults

A higher protein intake at breakfast does not compromise total daily protein intake in older adults

Introduction: A protein intake of 25–30 g per meal is suggested to maximally stimulate muscle protein synthesis in older adults in order to prevent sarcopenia. Protein intake at breakfast is often low and therefore breakfast offers the potential for protein suppletion. Since protein is known for its satiating effects, we explored the association between the amount of protein intake at breakfast and total daily protein intake in older adults. Methods: Baseline protein intake was assessed by a 3-day dietary record in 507 community dwelling older adults of 55 years and older participating in lifestyle interventions at the Amsterdam Nutritional Assessment Center. Multiple linear regression analysis was used to examine the association between protein intake at breakfast (in g) and total daily protein intake (in g, and g/kg body weight), adjusted for energy intake (kcal/d), sex, age and BMI. Interactions were tested for sex, age and BMI but were not significant (p>0.80). Results: Mean age was 67.6 ± (SD) 7.3 years, 42% was female, and mean BMI was 30.0 ± 5.6 kg/m2. Total daily protein intake was 81 ± 24 g which equals 0.96 ± 0.3 g/kg and 17.6 ± 3.7 percent of total energy intake. Protein intake at breakfast was 14 ± 7 g. A 10 g higher protein intake at breakfast was associated with a 6.7 g (SE = 1.0; P<0.001) and a 0.06 g/kg (SE = 0.01; P<0.001) higher total daily protein intake after adjustment for confounders. Key conclusions: A higher protein intake at breakfast does not compromise total daily protein intake in community dwelling older adults