To explore the effect of the photoperiod on the accumulation and distribution of dry matter in potato, a pot experiment was carried out in 2021 and 2022 with two varieties (Atlantic and Hezuo 88). The varieties were used as the main plot, and light treatments (short-day and long-day) were used as the subplot. The results showed that extended hours of light delayed tuber formation in Hezuo 88, however, the effect was not obvious for the Atlantic. Comprehensive analyses were carried out using the potato developmental process, dynamic equation fitting of the tuber and whole-plant dry matter accumulation, and the dry matter accumulation and distribution rate of each organ of the two varieties under two photoperiods. The two photoperiods had different effects on the parameters of rapid tuber and whole-plant dry matter accumulation: the starting point of the period of the rapid dry matter accumulation (t₁), the duration period of the rapid dry matter accumulation (Δt), and the average growth rate of the period of the rapid dry matter accumulation (V_mean). According to comprehensive analysis, tuber dry matter accumulation in Atlantic was the highest under the short-day condition, while Hezuo 88 showed the lowest tuber dry matter accumulation under the long-day condition and was the latest to enter the rapid tuber dry matter accumulation period. The whole-plant dry matter accumulation in Atlantic was the highest under the long-day condition and lowest in Hezuo 88; meanwhile, Hezuo 88 was the latest to enter the rapid whole-plant dry matter accumulation period. In terms of the dry matter accumulation and dry matter partitioning ratio of various organs, Hezuo 88 had the lowest mean tuber dry matter accumulation and partitioning ratio under the long-day condition but the highest mean stem, leaf, root, underground stem, and stolon dry matter partitioning ratio. On the contrary, Atlantic had the highest mean tuber dry matter accumulation and portioning ratio under the short-day condition but the lowest mean stem, leaf, root, underground stem, and stolon dry matter partitioning ratio. It was concluded that different varieties of potato respond differently to the photoperiod. In the case of Hezuo 88, prolonging the photoperiod affected the dynamics and distribution of dry matter accumulation; increased the stem, leaf, root, and underground stem dry matter partitioning ratio; and decreased the tuber dry matter partitioning ratio, which resulted in a decrease in tuber dry matter accumulation and consequently delayed the emergence of the equilibrium period between the aboveground and underground dry matter.

As the third-largest maize-producing province in China and a typical arid and semi-arid region, quantitatively evaluating the carbon and nitrogen footprints of maize production and their dominant factors is of great significance in guiding the high-yield, low-carbon, and sustainable development of maize production in the Inner Mongolia Autonomous Region. This study quantitatively evaluated the interannual evolution characteristics of the carbon and nitrogen footprints in maize production and their dominant factors in Inner Mongolia from 2003 to 2022 based on statistical yearbook data and emission parameter models. The results showed that from 2003 to 2022, the maize planting area, yield, and total yield in Inner Mongolia all increased, with an average annual increase of 97 kg ha⁻¹ in yield and 1.23 × 10⁶ Mg in total yield. The carbon and nitrogen footprints of Inner Mongolia maize production over the past 20 years had overall decreasing trends, while the nitrogen fertilizer bias productivity, net ecosystem carbon balance, and sustainability index had increasing trends. Carbon footprint reduced by an average of 5.2 kg CO₂ eq Mg⁻¹ per year, and nitrogen footprint reduced by an average of 0.21 g N eq kg⁻¹ per year. Currently, the transportation and production of fertilizer and field application of N fertilizer are the main controlling factors of GHG emissions from maize production. NO₃⁻-N, NH₄⁺-N leaching, and NH₃ volatilization from field application of N fertilizer are the main sources of reactive N losses. The application of simplified processes, such as phased regulation of nitrogen and controlled-release fertilizers, as well as conservation tillage, have broad prospects for emission reduction in maize production in Inner Mongolia.

Long-term irrational farming practices and low return of organic materials to the fields in the black soil area have led to reduced soil carbon and nitrogen stability and nutrient imbalance, which in turn affect soil fertility and crop yields. Straw return is an effective way to enhance soil organic matter and crop productivity, but the effects of long-term straw return under tilling practices on carbon and nitrogen sequestration and soil microbial stoichiometric equilibrium in black soil need to be further investigated. This study investigated the physical, chemical and biological properties of the 0–60 cm soil layer under deep tillage with straw return to the field (DTS), deep harrow with straw return to the field (DHS), rotary tillage with straw return to the field (RTS), no tillage with straw return to the field (NTS), and conventional tillage with straw removal (CT) on the basis of seven consecutive years of tillage pattern location trials in the black soil area of eastern Inner Mongolia. The results showed that DTS and NTS significantly increased the soil organic carbon (SOC), soil total nitrogen (TN), soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN) contents, and the SOC/TN ratio in the 0–40 cm soil layer, enhancing soil carbon and nitrogen sequestration capacity, while the concomitant increase in the average MBC/MBN ratio in the plow layer from 6.8 to 8.2. The soil microbial quotient increased by 29.0% and 26.2%, respectively, and the stoichiometric imbalance ratio decreased by 7.9% and 5.7%, respectively. Meanwhile, in terms of maize yield from 2018 to 2024, DTS showed the most stable and significant yield increase with 41.53%. Whereas NTS showed a higher yield increase potential with a 27.36% increase in yield as the number of years of straw return increased. Therefore, DTS and NTS are superior tillage methods to improve the quality of the black soil tillage layer, to promote soil microbial carbon and nitrogen balance, and to increase crop yields.

This study investigated how different organic fertilization practices affect productivity, stability, and nitrogen use efficiency in the rotation systems of the Hetao Irrigation District. The research was based on a long-term field experiment (2015–2025), with a chemical fertilizer-only treatment as the control (CK). Four organic fertilization treatments were evaluated: farmyard manure application (CM), straw incorporation (CS), green manure cultivation and incorporation (CG), and a combined green manure plus straw treatment (CGS). Based on three consecutive years of observations (2023–2025), the impacts of these treatments on crop yield, yield composition and stability, plant nitrogen accumulation and allocation, and nitrogen use efficiency were systematically analyzed. Both CM and CS significantly increased maize equivalent yield (MEY) compared with the other treatments, by 33.68–66.04% and 16.05–24.21%, respectively. CM’s productivity advantage was primarily driven by higher biomass accumulation, whereas CS’s advantage was largely due to improvements in the harvest index. In terms of stability, CM exhibited the lowest coefficient of variation (CV), indicating the highest static stability, while CS showed a regression coefficient (b_i) close to 1, indicating stronger dynamic stability. CM also significantly enhanced total plant nitrogen accumulation, nitrogen recovery efficiency (NRE), and nitrogen use efficiency (NUE), while optimizing nitrogen allocation to grain. CS significantly improved nitrogen internal efficiency (NIE), promoting more efficient conversion of absorbed nitrogen into grain yield. CG and CGS did not show clear advantages across productivity, stability, or most nitrogen use efficiency-related indices. Overall, in the Hetao Irrigation District, farmyard manure application is an effective strategy for achieving both high and stable yields, whereas straw incorporation offers stronger environmental adaptability. Both practices represent practical and effective approaches for improving the sustainability of rotation systems.

Maize, as a major cereal crop in China, is vital for national food security, and appropriate nitrogen fertilization is essential for its growth and yield. Avoiding excessive nitrogen fertilizer application while maintaining productivity remains a critical challenge for sustainable agriculture. Although straw returning is widely adopted to reduce chemical fertilizer inputs, its effectiveness is often regionally constrained. In the West Liaohe Plain, low temperature and spring drought limit straw decomposition and nutrient release, making it difficult to reduce nitrogen fertilizer input and improve fertilizer use efficiency. Therefore, this study examined the effects of different nitrogen management modes on straw decomposition, nutrient release, mineral fertilizer substitution potential, soil available nutrients, and maize yield under shallow buried drip irrigation with integrated water and fertilizer management. A field experiment was conducted with five nitrogen (N) fertilizer management treatments: a conventional fertilization treatment (CK), in which 15% of total N was applied as starter fertilizer; two increased starter N treatments, in which 30% (30%N) and 45% (45%N) of total N were applied as starter fertilizer; and two organic substitution treatments, in which 30% (30%ON) and 45% (45%ON) of mineral N fertilizer were substituted with decomposed sheep manure based on equivalent total N input. Straw decomposition and nutrient release were measured using the nylon mesh bag method and fitted with an exponential decay model. The mineral fertilizer substitution potential was estimated based on straw nutrient release, while soil available nutrient dynamics in the 0–40 cm soil layer were analyzed, and the Mantel test and PCA were used to assess their relationships. Organic substitution promoted straw decomposition. The 30%ON treatment showed the highest rate at 70.91%, which was 19.2% higher than that of CK, and it exhibited a higher theoretical maximum decomposition rate (a), higher decomposition rate constant (k), and a shorter half-life. All treatments increased nutrient release and soil available nutrients, and organic substitution demonstrated stronger temporal persistence and more uniform vertical distribution among soil layers. The 30%ON treatment increased straw nutrient release by 4.8% to 18.2% and enhanced mineral fertilizer substitution potential. Although the 30%ON treatment did not increase yield in the first experimental year, it showed a significant yield advantage in the second year, which coincided with greater straw nutrient release and higher soil available nutrient levels under this treatment. Substituting 30% of mineral N fertilizer with organic fertilizer under shallow buried drip irrigation (300 kg N ha⁻¹) optimized the C/N balance of the input system and facilitated straw decomposition and nutrient release. The continuous accumulation of soil available nutrients under this treatment, together with sustained straw nutrient release, was associated with a significant yield advantage in the second experimental year. Therefore, the 30%ON treatment may represent an appropriate management strategy for coordinating straw resource utilization, soil fertility maintenance, and stable maize production in the West Liaohe Plain.

The degradation of soil structure and organic carbon in the black soil region of Northeast China threatens sustainable crop production, and straw return combined with appropriate tillage may offer an effective strategy for soil restoration. However, the depth-dependent mechanisms by which straw management–tillage systems regulate aggregate stability, labile carbon distribution, and soil quality under long-term straw return remain unclear. Based on a seven-year field experiment established in 2018 in eastern Inner Mongolia, this study compared conventional tillage with straw removal (CT) and four straw-return practices: deep tillage with straw return (DTS), deep harrowing with straw return (DHS), rotary tillage with straw return (RTS), and no-tillage with straw mulching and direct seeding (NTS). Soil aggregate stability, soil organic carbon (SOC), SOC stock, labile organic carbon fractions, microbial biomass carbon, carbon-acquiring enzyme activity, available nutrients, and soil quality index (SQI) were evaluated across the 0–60 cm soil profile. Straw return combined with tillage improved soil structure, carbon accumulation, nutrient availability, and SQI, with stronger responses observed under NTS and DTS. NTS mainly increased macroaggregate formation and the accumulation of SOC, light fraction organic carbon (LFOC), and particulate organic carbon (POC) in the 0–20 cm layer and was associated with the highest SOC stock in the whole profile. In contrast, DTS showed greater increases in SOC stock, dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), available nutrients, and SQI in the 20–40 cm layer, likely related to deeper straw incorporation. Partial least squares (PLS) path modeling indicated that labile carbon pools were closely associated with the relationship between aggregate stability and soil quality improvement. These results suggest that NTS appears promising for surface soil conservation, whereas DTS may be beneficial for improving subsoil fertility and carbon sequestration in black soil farmland.