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Returning straw to the field is the most significant straw utilization technique for China’s green development. It can provide nutrients for crop growth and improve soil organic matter content. However, there are no standard parameters for measuring the nutrient content of straw directly returned to the field. In addition, the nutrient content of straw in the field is disregarded and the least researched. Therefore, to address these issues, the current research examines the main nutrient composition of straw returned directly to fields and the potential substitution of straw for chemical fertilizers. This study used the latest data on the crop straw-to-grain ratio and straw’s direct return to the field from the Database of Agricultural Crops Straws Resources in China (DACSRC) as the basis for a detailed estimation of the amount of crop straw nutrient resources and straw’s direct return to the field. The straw nutrient resources were measured based on straw yield and the nitrogen (N), phosphorous (P2O5), and potassium (K2O) contents. The results reveal that the maximum amount of straw returned directly to the fields in China was 517 teragram (Tg), while 128 Tg (25%) of the total was not collected but left on the field. The North China region had an enormous amount of direct straw return at 176 Tg (34%), while South China had the least amount at 26 Tg (5%). The amounts of seasonally available N, P2O5, and K2O from straw directly returned to fields are 2 Tg, 1 Tg, and 7 Tg, respectively. In addition, the amount of available straw nutrient resources returned to the field per hectare (ha) was 78 kg. The quantity of straw-originating seasonally available nutrients corresponds to 23% of the chemical fertilizers applied, which can substitute 10% N, 9% P2O5, and 58% K2O. The study provides critical insights on effective ways to improve straw fertilization through an increased rate of straw returned directly to fields and releasing seasonal nutrients.

Three main crop straws including corn straw (Zea mays, CS), rice straw (Oryza sativa, RS), and wheat straw (Triticum aestivum, WS), and two forages including alfalfa hay (Medicago sativa, AH) and corn silage (Zea mays, CSil) were analyzed in order to compare their ruminal degradability, indigestible neutral detergent fiber (iNDF), intestinal digestibility (ID), and their total-tract digestibility (TTD) of crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) using both an in situ nylon bag technique and a mobile nylon bag technique. The forage samples were incubated in the rumen for 6, 12, 16, 24, 36, 48, 72, and 288 h, respectively, to determine their ruminal degradability. Prior to intestinal incubation, forage samples were incubated in the rumen for 12 h and 24 h to determine the ruminal degradable content of CP, NDF, and ADF, respectively, and for 288 h to determine their iNDF288 content. Residues from the ruminal undegradable fractions (12 h for CP, 24 h for NDF and ADF) were subsequently inserted into the duodenum through a cannula to determine their intestinal digestible content. Here, the TTD of CP, NDF, and ADF were determined as the ruminal degradable content + intestinal digestible content. The results showed that AH had the highest iNDF2.4 (calculated as acid detergent lignin content × 2.4) and iNDF288 values (379.42 and 473.40 g/kg of NDF), while CS and CSil had the lowest iNDF2.4 values (177.44 and 179.43 g/kg of NDF). The ruminal degradability of CP, NDF, and ADF for CS, RS, and WS were lower than those of AH and Csil during the first 48 h of incubation. The potential degradation fraction of CP, NDF, and ADF for CSil was the highest; CS, RS, and WS were intermediate; and AH was the lowest (p < 0.05). CS, RS, and WS had a lower intestinal digestibility with respect to their rumen undegradable content of NDF (p < 0.05), and lower TTD of CP, NDF, and ADF (p < 0.05) compared to AH and CSil. General regression equations with satisfactory accuracy (R2 ≥ 0.828) were derived to predict iNDF288 and TTD based on their chemical compositions and the ruminal degradation kinetics of different forages. Incorporating this information into rations could improve our ability to optimize main crop straws utilization and milk production.

Anthropogenic global warming and the depletion of nonrenewable resources necessitate a transition towards bioenergy to accelerate sustainable development and carbon neutrality. This study quantified the availability and energy potential of crop (cereals, legumes, roots and tubers) straws based on data from the Northern, North East and Savannah regions in Ghana. The annual technical straw potential was 2,967,933 tonnes, whilst the crop straws with the highest technical potential were yam (935,927 tonnes), groundnut (485,236 tonnes), maize (438,926 tonnes) and soybean (374,564 tonnes). The technical energy potential of all the crop straws was 42,256 TJ, although the energy potential of yam, groundnut, maize and soybean was 13,922 TJ, 7611 TJ, 5704 TJ and 5409 TJ, respectively. There was a linear correlation between the straw produced and the energy potential per region. The Northern region (28,153 TJ) recorded the highest energy potential followed by the Savannah (8330 TJ) and North East (5773 TJ) regions. To serve as context, the research placed an emphasis on the sustainability of crop straws for bioenergy and added a brief analysis of the life cycle assessment (LCA) of bioenergy scenarios to explore the environmental sustainability of crop straw-based power generation. This study will serve as a reference in understanding LCA inference on practicable research of crop straw-based, power plant expansion in Ghana and Sub-Saharan Africa (SSA).

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Steam reforming (SR) of single model molecules (acetone, butanol, and ethanol) and a specific mixture (butanol/acetone/ethanol = 6/3/1, mass ratio) assumed as a model of biobutanol raw mixture has been researched over mesoporous Ni x /MgO catalysts (x represented nickel mole percent in Ni–Mg) at 673–873 K. The result showed reactant conversion at lower temperatures allowed ranking the three single-molecule compounds as the function of SR activity as follows: ethanol > acetone > butanol. The catalytic performance of mesoporous Ni0.12/MgO catalyst with lower Ni component containing enough active sites outperformed that of mesoporous Ni0.16/MgO catalyst which was more inclined to sinter in all SR tests of single-component compounds except at 673 K. On the contrary, the catalytic behavior of Ni0.16/MgO (richer in nickel) was superior to that of Ni0.12/MgO catalyst in SR of multicomponent compounds. Moreover, in acetone–butanol–ethanol steam reforming (ABESR), SR of ethanol suffered competition from acetone and butanol, suppressing ethanol molecule access to the limited active sites of the catalyst. As a consequence, the conversion of ethanol in SR of multicomponent compounds decreased compared to that in SR of pure ethanol.

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