Global attention to climate change issues, especially air temperature changes, has drastically increased over the last half-century. Along with population growth, greater surface temperature, and higher greenhouse gas (GHG) emissions, there are growing concerns for ecosystem sustainability and other human existence on earth. The contribution of agriculture to GHG emissions indicates a level of 18% of total GHGs, mainly from carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Thus, minimizing the effects of climate change by reducing GHG emissions is crucial and can be accomplished by truly understanding the carbon footprint (CF) phenomenon. Therefore, the purposes of this study were to improve understanding of CF alteration due to agricultural management and fertility practices. CF is a popular concept in agro-environmental sciences due to its role in the environmental impact assessments related to alternative solutions and global climate change. Soil moisture content, soil temperature, porosity, and water-filled pore space are some of the soil properties directly related to GHG emissions. These properties raise the role of soil structure and soil health in the CF approach. These properties and GHG emissions are also affected by different land-use changes, soil types, and agricultural management practices. Soil management practices globally have the potential to alter atmospheric GHG emissions. Therefore, the relations between photosynthesis and GHG emissions as impacted by agricultural management practices, especially focusing on soil and related systems, must be considered. We conclude that environmental factors, land use, and agricultural practices should be considered in the management of CF when maximizing crop productivity.

Manure impacts labile pools of soil organic carbon (SOC) and nitrogen (N) which can influence soil microbial composition (MCC) and enzyme activities, and hence soil health. The present study was conducted to investigate the impacts of long-term dairy manure and inorganic fertilizers (INF) on soil carbon (C) as well as nitrogen (N) fractions, enzyme activities, and microbial community structure in different time horizons at planting (P), one month after planting (1MAP), and after harvesting (H) under corn (Zea mays L.)-soybean (Glycine max L.) rotation. Study treatments included three manure application rates (low, phosphorus-based recommended rate; medium, nitrogen-based recommended rate; and high, the double rate of medium nitrogen based recommended rate), two INF rates (medium only nitrogen additions; and high nitrogen, phosphorus, potassium, zinc, and sulfur additions) and a control (no application of manure and/or inorganic fertilizer). In comparison to the INF, the dairy manure not only significantly increased chemical fractions of C and N but also impacted the enzyme activities. Average urease activity after manure was applied was shown to be 26.8% higher than it was with INF applied at planting. The β-Glucosidase activity was 6 and 14% higher with manure than it was with INF at 1MAP and harvesting, respectively. The cold-water extractable nitrogen (CWEN) was enhanced with high manure rate at all timings of sampling compared to the high fertilizer rate (53%), and CK (90%). Principal component analysis indicated that MCC under manure differed from those under the INF treatments. The total bacteria/total fungi ratio at planting was increased with the INF compared to the manure addition. Pearson’s correlation analysis showed that CWEC, CWEN, and enzyme activities especially β-Glucosidase activity were the key determinants of MCC. Data from this study showed that, compared to inorganic fertilizers, manure can be beneficial in enhancing soil health indicators.

Diversification of crop species and minimum mechanical soil disturbance are the interlinked principles of conservation agriculture that are beneficial in improving soil physical and hydrological properties, and hence crop productivity. The present study was conducted to assess the long-term impacts of crop rotational diversity and tillage on soil water infiltration (qs), soil water retention (SWR), pore size distribution (PSD), bulk density (ρb) and soil penetration resistance (SPR). The study was established in 1991 at Beresford, South Dakota, and included three crop rotation systems (2-year, maize (Zea mays L.)–soybean (Glycine max L.); 3-year, maize–soybean–wheat (Triticum aestivum L.); and 4-year, maize–soybean–wheat–oat (Avena sativa L.)) and two tillage systems (NT, no-tillage; and CT, conventional tillage). Soil samples were collected only under maize and soybean phases of the crop rotations. Our results showed that NT with 4-year rotation had the lowest ρb under maize and soybean phases (1.21 and 1.19 g cm–3 respectively) compared with the CT system. Similarly, NT with 4-year rotation decreased SPR by 20% compared to CT with 4-year rotation in the soybean phase. Soils managed under NT with 4-year rotation in the soybean phase retained 27, 28, 28, 32, 33, 31 and 26% more water compared with CT and 4-year system at 0–7.5 cm depth at 0, –0.4, –1.0, –2.5, –5.0, –10 and –30 kPa matric potentials respectively. A similar trend was observed for qs under the same treatments, in which it was 31% higher under NT than under CT, both with 4-year rotation. Data from this study showed that diversified crop rotation under NT enhanced soil physical and hydrological properties compared with CT with less diverse systems (e.g. maize–soybean).