Intensifying soil health means managing soils to enable sustainable crop production and improved environmental impact. This paper discusses soil health intensification by reviewing studies on the relationship between soil structure, soil organic matter (SOM), and ecosystem carbon budget. SOM is strongly involved in the development of soil structure, nutrient and water supply power, and acid buffering power, and is the most fundamental parameter for testing soil health. At the same time, SOM can be both a source and a sink for atmospheric carbon. A comparison of the ratio of soil organic carbon to clay content (SOC/Clay) is used as an indicator of soil structure status for soil health, and it has shown significantly lower values in cropland than in grassland and forest soils. This clearly shows that depletion of SOM leads to degradation of soil structure status. On the other hand, improving soil structure can lead to increasing soil carbon sequestration. Promoting soil carbon sequestration means making the net ecosystem carbon balance (NECB) positive. Furthermore, to mitigate climate change, it is necessary to aim for carbon sequestration that can improve the net greenhouse gas balance (NGB) by serving as a sink for greenhouse gases (GHG). The results of a manure application test in four managed grasslands on Andosols in Japan showed that it was necessary to apply more than 2.5 tC ha⁻¹ y⁻¹ of manure to avoid reduction and loss of SOC in the field. Furthermore, in order to offset the increase in GHG emissions due to N₂O emissions from increased manure nitrogen input, it was necessary to apply more than 3.5 tC ha⁻¹y⁻¹ of manure. To intensify soil health, it is increasingly important to consider soil management with organic fertilizers that reduce chemical fertilizers without reducing yields.

Health risks due to heavy metal (HM) contamination is of global concern. Despite concerns of high levels of HMs in soils near Kabwe mine in Zambia, edible crop production is common, posing potential health risks. This study assessed the potential of chicken manure (CM), triple superphosphate (TSP) and a blended fertilizer (BF; consisting of Nitrogen, Phosphorous and Potassium (NPK) fertilizer and composted chicken manure) to reduce lead (Pb), zinc (Zn) and cadmium (Cd) in soils and their accumulation in maize grown near the Kabwe mine. Maize was grown to maturity and its HM concentrations and associated health risk indices were calculated. All soil amendments decreased bioavailable soil Pb concentrations by 29–36%, but only CM decreased Zn, while the amendments increased or had no effect on Cd concentrations compared to the control. The amendments reduced Pb (>25%) and Zn concentrations (>18%) in the maize stover and grain. However, Cd concentrations in maize grain increased in the BF and TSP treatments. Bioaccumulation factors showed that Cd had the highest mobility from the soil into maize stover and grain, indicating the need for greater attention on Cd in Kabwe despite its apparently lower soil concentration compared to Pb and Zn. The hazard quotients for Pb and Cd were much greater than one, indicating a high risk of possible exposure to toxic levels by people consuming maize grain grown in this area. This study demonstrated the significant potential of manure and phosphate-based amendments to reduce Pb and Zn, and to some extent Cd, uptake in maize grain and consequently reduce associated health risks.

A 3-year study was conducted in cornfield to evaluate how composted cattle manure application affects net global warming potential (GWP; the sum of nitrous oxide (N₂O) and methane (CH₄) minus net ecosystem carbon balance (NECB)) and greenhouse gas intensity (GHGI; net GWP per unit of plant biomass yield). In the first experiment, conducted from 2010 to 2012, five fertilization strategies that included an unfertilized control plot, inorganic fertilizer-only plot, two plots with inorganic fertilizer plus composted cattle manure, and composted cattle manure-only plot were established. In the second experiment composted cattle manure was applied in autumn 2012 and the field was subdivided into three plots in spring 2013, with one plot receiving additional composted cattle manure, the second plot received additional inorganic fertilizer and the third plot did not receive any additional fertilization. Fluxes of N₂O, CH₄ and CO₂ were measured using the static closed chamber method. NECB was calculated as carbon (C) inputs minus C output (where a negative value indicates net C loss). In experiment 1, manure application significantly increased NECB and reduced net GWP by more than 30% in each of the three years of the study. GHGI in the manure-amended plots was lower than in other plots, except in 2012 when the manure-only plot had higher GHGI than fertilizer-only plot. Application of inorganic fertilizer alone increased GWP by 5% and 20% in 2010 and 2011, but showed a 30% reduction in 2012 relative to the unfertilized control plot. However, due to higher net primary production (NPP), fertilizer-only plot had lower GHGI compared to the control. Application of inorganic fertilizer together with manure showed the greatest potential to reduce GWP and GHGI, while increasing NPP and NECB. In experiment 2, additional manure or inorganic fertilizer application in spring increased NPP by a similar amount, but additional manure application also increased NECB, and decreased GWP and GHGI. Manure application, as a partial substitute or supplemental fertilizer, shows potential to mitigate GWP and GHGI.