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Ridge-furrow film mulching (RFFM) and nitrogen (N) fertilization have been widely used in semi-arid regions, it is particularly important to clarify the mechanism of crop physiological indicators in response to RFFM. A two-year (2018 and 2019) field experiment was conducted on summer maize under RFFM (including biodegradable film mulching (B) and plastic film mulching (P)) at N fertilizer application rate of 0 (N0), 90 (N1), 180 (N2) and 270 (N3) kg N ha–1. The aims of this research were to 1) explore the effects of different film mulching and N application rates under RFFM on photosynthesis, water utilization, and yield; 2) identify key factors and their contribution to yield. The results showed that RFFM and nitrogen application significantly improved net photosynthesis rate (P n), stomatal conductance (G s), transpiration rate (T r), intrinsic water use efficiency (WUE i) (grain-filling stage), the maximum quantum yield of PSII photochemistry (F v / F m), energy transformation potential activities of PSII (F v / F o), the effective quantum yield of PSII photochemistry (Φ PSII), photochemical quenching of variable chlorophyll fluorescence (qP), non-photochemical chlorophyll fluorescence quenching (NPQ), chlorophyll ab (Chl ab), evapotranspiration (ET) and yield, but decreased chlorophyll a/b (Chl a/b) and soil water storage (SWS). The maximum P n , T r , G s , WUE i , F v / F m. F v / F o , Φ PSII , qP , and Chl ab (anthesis stage) all appeared in N2. At the same N application rate, the positive effects on photosynthetic and chlorophyll fluorescence (ChlF) of the plastic film were better than biodegradable film, especially in water use efficiency (WUE). Nitrogen deficiency had significantly negative effects on various parameters (Photosynthetic parameters, ChlF, Chl ab, grain yield), while nitrogen application (N > N1) had strong positive effects. Photosynthetic parameters, F v / F m , F v / F o , NPQ , Chl ab, ET, and WUE had strong positive effects on yield. The grain yield of the plastic film were slightly better (5.03% on average) than biodegradable film, but from the perspective of sustainable development, we recommend that biodegradable film and N2 should be used in the semi-arid regions of China. • Four N rates were applied to summer maize under ridge-furrow with polyethylene film and biodegradable film mulching. • RFFM and N application significantly improved Photosynthetic parameters, ChlF, and yield, but decreased Chl a/b and SWS. • Photosynthetic parameters, F v / F m , F v / F o , NPQ , Chl ab, ET and WUE had strong positive effects on yield. [ABSTRACT FROM AUTHOR]

In semi-arid regions of northwest China, the planting pattern of double ridge-furrow with full film mulching (DRFM) is widely used to improve maize productivity. However, little is known about reasonable application amounts of nitrogen (N), phosphorus (P), and potassium (K) fertilizers for maize under this planting pattern, and local farmers applying unreasonably large fertilizer amounts results in wasted resources and environmental pollution. Therefore, the effects of N, P, and K fertilizer application amounts on the leaf area index (LAI), aboveground dry matter accumulation and translocation, grain yield and water productivity (WP), and nutrient uptake and utilization by maize under DRFM were studied in 2018 and 2019. A field experiment was conducted with five fertilization levels under DRFM, and the treatments of which were: M1: 60 kg N ha–1, 60 kg P 2 O 5 ha–1, 45 kg K 2 O ha–1; M2–5 each increased N, P 2 O 5 , and K 2 O by 60 kg ha–1, 30 kg ha–1 and 45 kg ha–1, respectively, compared to the previous treatment. No fertilizer under flat planting with non-film mulching was included as the control. The results showed that the logistic model better described the dynamic accumulation process for aboveground dry matter. The LAI, maximum aboveground dry matter accumulation rate, average accumulation rate for aboveground dry matter, and N, P, and K uptake initially increased, but then declined as fertilizer applications increased, and all factors reached their maximum values under M3. Dry matter translocation and accumulation after silking were positively correlated with grain yield. Grain yield and WP were greatest under M3 with an average of 10.77 t ha–1 and 29.12 kg m–3 across the two years, which were 4.46–138.19% and 1.29–153.15% greater than the other treatments, respectively. Although N, P, and K fertilizer use efficiency was lower under M3 than M1 and M2, it produced a much higher yield and WP. In summary, 180 kg N ha–1, 120 kg P 2 O 5 ha–1, and 135 kg K 2 O ha–1 is recommended as the optimal N, P, and K fertilizer application scheme for maize under DRFM to achieve the great yield, and water and fertilizer use efficiencies in northwest China. • Effect of NPK on maize productivity under DRFM were explored. • Rational NPK under DRFM increased dry matter and nutrient absorption. • Post DM was positively correlated with GY under DRFM. • DRFM with 180–120–135 kg N–P 2 O 5 –K 2 O ha–1 improved GY and resources use efficiency. [ABSTRACT FROM AUTHOR]

With the extensive use of plastic film, a large number of residual film accumulated in the farmland, bringing a huge negative impact on agricultural production. Studying the effect of residual film on roots is helpful to understand the damage mechanism of residual film on crop growth. Thus, a two-year field experiment was conducted with 0 (M0), 90 (M90), 180 (M180), 360 (M360), and 720 (M720) kg ha−1 residual film, and sine and logistic functions were used to simulate root growth and vertical distribution of maize. Results showed that root length decreased with residual film increasing and was more sensitive to residual film at tasseling, filling and maturity stages than at seedling and jointing stages. The results of the sine function fitting the total root length showed that the potential maximum root length was decreased and the rooting time was delayed, and the root growth time was shortened with the amount of residual film increasing. M90 had no significant effect on root length but residual film equal to or greater than 180 kg ha−1 had significant negative effects on root length. M180, M360 and M720 significantly reduced the actual total root length by 13.7%, 23.8% and 33.3%, and reduced the potential root length by 9.4%, 17.1% and 21.8%. M360 and M720 significantly shortened the growth time by 3.8% and 6.6%. The logistic function fit the vertical root distribution well. Residual film decreased the root length in deep soil and gathered roots in the soil layer near the depth of d 50 at which 50% of the root length was accumulated. Residual film decreased the soil depth where 50% and 95% root length were accumulated and increased the proportion of root length in 0–30 cm soil layer. This adverse effect increased with residual film amount increasing. The dry matter of stems, leaves and ears decreased with residual film increasing. M90 reduced the above-ground dry matter insignificantly and the other treatments with residual film had significant effects. At the maturity stage, the above-ground dry matter in M90, M180, M360 and M720 was reduced by 2.4%, 14.2%, 22.2% and 29.4%, compared with M0. Residual film decreased evapotranspiration (ET), grain yield and water use efficiency (WUE) significantly except M90. ET, yield and WUE were reduced by 1.7%, 3.0% and 1.1% in M90, and 2.5%, 17.1% and 16.1% in M180, and 6.2%, 27.1% and 23.4% in M360, and 8.5%, 34.7% and 30.8% in M720, respectively. In summary, the residual film beyond 180 kg ha−1 had a significant negative effect on summer maize. This information will be useful to better understand and respond to residual film pollution and ensure safe agricultural production. • The sine function well fitted the total root length density (RLD) in whole season. • Residual film delayed rooting and reduced the maximum RLD and root growth time. • The logistic function fitted the accumulative RLD with soil depth well. • Residual film reduced roots in deep soil and gathered roots in shallower soil. • Residual film exceeding 180 kg ha−1 significantly reduced yield and WUE [ABSTRACT FROM AUTHOR]

The farming practice of fully mulched double ridge-furrow with polyethylene (PE) film has been widely used to improve productivity of many staple crops in arid and semi-arid regions of northwest China. However, the residual PE film has caused many environmental problems such as "white pollution" and land degradation. Biodegradable film might be a good substitute for PE film in agriculture production, but the evidence for the appropriate biodegradable film mulching pattern for maize is lacking. A 2-year field experiment was carried out to identify a suitable biodegradable film mulching pattern for maize at a typical rain-fed semi-arid site on the Loess Plateau. The local widely cultivated maize variety 'Luodan 9′ was sown in five planting patterns: 1) conventional flat planting without film mulching (CK); 2) flat planting with full mulching with biodegradable film (FB); 3) ridge-furrow planting with biodegradable film mulching on ridges (RFB); 4) double ridge-furrow planting with full biodegradable film mulching (DRFB) and with full transparent PE film mulching (DRFP). The results indicated that biodegradable film mulching patterns (including FB, RFB and DRFB) significantly increased soil hydrothermal conditions, improved leaf area index, shoot and root biomass, and thus enhanced maize yield and water use efficiency (WUE) in comparison to CK (P < 0.05). Among the three biodegradable film mulching patterns, maize yield and WUE in DRFB (average across two growing seasons) were 9.7% and 11.7% significantly greater than FB, and were 9.9% and 12.2% significantly greater than RFB. In addition, maize yield and WUE in DRFB did not differ significantly from those in DRFP, except that the maize yield was 5.2% (P < 0.05) lower than DRFP in 2013 (a warm and dry season). Present field demonstration clearly indicated that DRFB could serve as a promising option to ameliorate soil hydrothermal conditions, improve maize growth and yield performance, boost WUE, and simultaneously reduce environmental risks such as "white pollution" in rain-fed semi-arid regions of northwest China. • Biodegradable film (BF) mulching increased yield and WUE than no film mulching. • Double ridge-furrow with BF full mulching (DRFB) greatly improved soil hydrothermal conditions. • Yield and WUE only reduced by 2.9% and 4.4% for DRFB than plastic film mulching. • DRFB is a suitable BF mulching pattern for maize production. [ABSTRACT FROM AUTHOR]

• Four N rates were applied to summer maize under biodegradable film and plastic film. • The proposed model provided a powerful simulation of the grain-filling process and required relatively few input variables. • The optimal nitrogen application rate of 205 kg ha-1 and 196 kg ha-1 for BM and PM, respectively. Grain-filling is a key stage allowing for the achievement of high grain yield. The ridge-furrow film mulching (RFFM) farming system has been widely adopted as a water saving and yield-improving planting pattern on the Loess Plateau of China. However, there is no convenient and effective model to understand the mechanism of maize grain-filling and effective nitrogen (N) management to obtain high grain yield under RFFM and N fertilizer. A two-year (2017–2018) field experiment was conducted on summer maize under RFFM (biodegradable film mulching (BM) and PE film mulching (PM)) and nitrogen fertilizer (0 (N0), 90 (N1), 180 (N2) and 270 (N3) kg N ha−1). The results showed that the 100-kernel dry weight was successfully simulated by the proposed model. After optimizing parameters, the model not only achieved minimum input requirements, but also successfully regulated N application. Moreover, characteristic parameters of grain-filling were significantly affected by the interaction of RFFM and N. N was beneficial for the improvement of the final 100-kernel dry weight (a) and grain-filling rate (V m a x , V ¯) and was more improved under BM. The N1 with PM treatment reached the maximum grain-filling rate (V m a x) earlier. The maximum grain-filling rate (V m a x) and average rate of grain-filling (V ¯) of PM was more sensitive to high N than BM. Parameters of the gradual-growing period were significantly affected by RFFM or N, but the interaction between RFFM and N had extremely significant effects on parameters of the fast-growing and slow-growing periods. For BM, N could improve the rate of three periods of grain-filling, and the N2 treatment was the best in the fast-growing and slow-growing periods. For PM, N could improve the rate of the gradual-growing period. According to the optimized model, the optimal nitrogen application rate of BM and PM was 205 kg ha−1 and 196 kg ha−1, respectively. Based on this optimized model, we could better understand the grain-filling process and achieve the appropriate nitrogen application rate. [ABSTRACT FROM AUTHOR]

The biodegradable film is an alternative to polyethylene film due to polyethylene residue pollution, but whether the biodegradable film can replace polyethylene film in terms of root growth, utilization of water and nitrogen, yield, and reducing N application remains unclear. Therefore, two-year field trials, involved two films (biodegradable film and polyethylene film) as the main plots and four nitrogen levels (0 (N0), 90 (N1), 180 (N2), and 270 (N3) kg N ha–1) as the subplots, were conducted. The results showed that compared with N0, N application significantly increased root length density (0–20 cm layer), root surface area density (0–10 cm layer), root weight (0–10 cm layer), and root/shoot ratio by 41.6%, 38.8%, 89.8%, and 33.0% on average for biodegradable film and by 40.3%, 33.9%, 61.5%, and 23.3% for polyethylene film, respectively. However, N application only significantly increased the root-bleeding sap per unit area (RBS) by 20.1% for biodegradable film compared to N0. Furthermore, N-fertilization significantly increased shoot dry matter, evapotranspiration (ET), water use efficiency (WUE), nitrogen use efficiency (NUE) (except for N3), and yield by an average of 31.8%, 9.5%, 33.2%, 7.9%, and 46.1% (biodegradable film), 24.8%, 11.6%, 34.4%, 7.5%, and 50.3% (polyethylene film), respectively, compared with N0. Compared with polyethylene film, root length densities, root surface area densities, root weights in the 0–10 cm layer, and WUE were significantly lower, but RBS (except for N0), ET, and NUE were significantly higher under biodegradable film. Path analysis showed that both improving root length density and root weight were conducive to increasing dry matter accumulation, WUE, and yield for two films. The optimum N rate was also found at 173.2 kg ha−1 for biodegradable film and 182.1 kg ha−1 for polyethylene film, which could increase NUE. Therefore, ridge-furrow with biodegradable film mulching combined with 173.2 kg N ha−1 could achieve the goal of replacing polyethylene film in terms of high yield, efficient utilization of nitrogen, and reducing N application. • N and PE film increased root parameters in topsoil but biofilm increased root activity. • Improving root length density and root weight were conducive to increasing WUE and yield. • ET and NUE were higher but WUE was lower under biofilm than under PE film. • Biofilm combined with 173.2 kg N ha−1 in ridge-furrow planting could replace PE film. [ABSTRACT FROM AUTHOR]

• The ET partitioning of maize was obtained under different management practices. • The ET partitioning varied with management practices, growth stages and years. • RFBM was recommended for maize production in northwest China in dry and wet years. Exploring the effects of film mulching and nitrogen (N) on crop transpiration (E t), soil evaporation (E s), crop actual evapotranspiration (E T a), and their relationships with yield and water use efficiency (WUE) is vital to improve understanding of crop water consumption and production. A 3-year (2017―2019) maize field trial was designed with three film mulching patterns (flat planting without mulching (FPNM), ridge-furrow with biodegradable film mulch over the ridge (RFBM), and ridge-furrow with plastic film mulch over the ridge (RFPM) as main plots and N application levels (0 and 180 kg N ha–1) as subplots. The results showed that RFBM and RFPM increased E t more than FPNM when no N was applied. However, the E t increment for FPNM was higher than for RFBM and RFPM during the 2017 (dry) and 2019 (wet) seasons when N was applied. Both RFBM and RFPM decreased E s , E T a , and the total E s / E T a ratio compared with FPNM, regardless of N application, and improved yield and WUE when no N was applied across all three seasons. Applying N to RFBM and RFPM significantly improved yields in 2017 and 2018 (normal) seasons and increased WUE across all three seasons compared with FPNM. However, in 2019, maize yields were 4.68% and 4.48% higher in FPNM than in RFBM and RFPM when N was applied. Nitrogen mainly increased E t during the reproductive stage in FPNM and RFPM, but increased E t during the mature stage in RFBM. In contrast, N for three planting patterns decreased E s at the seeding and filling stages but increased E s at the jointing and mature stages during the 2017 and 2018 seasons. However, in the 2019 season, N application decreased E s in FPNM and RFBM, but increased E s in RFPM. N application also improved yield and WUE by 23.37–59.56% and 23.78–60.36% across the three seasons, respectively. Thus, RFBM and RFPM are recommended for maize production in northwest China, and RFBM with N application can replace RFPM in dry and wet seasons. [ABSTRACT FROM AUTHOR]

A theoretical basis for optimizing mitigation and adaptation to future climate change can be obtained by determining the carbon balance and their control mechanism in agroecosystems. To better understand summer maize (Zea mays L.)/winter wheat (Triticum aestivum L.) agroecosystems in dry semi-humid carbon balance mechanism, we conducted an in-depth analysis of three-year (2019.6–2022.6) seasonal dynamics of carbon fluxes and their driving factors in summer maize/winter wheat cropland in the Guanzhong Plain combined with path analysis. The results showed that net radiation (R n) was the main direct controlling factor of the net ecosystem exchange (NEE) in the summer maize growing season, followed by leaf area index (LAI). However, LAI was the main factor controlling the seasonal variation of NEE in the winter wheat growing season, followed by R n. Furthermore, LAI was the dominant direct driving factor for the gross primary productivity (GPP) in the summer maize and winter wheat growing seasons. In addition, LAI was the dominant driving factor for the total ecosystem respiration (TER) in the summer maize season, while R n (indirect effect) and LAI (direct effect) were the main controlling factors of TER in the winter wheat season. The NEE values of the summer maize system, winter wheat system, and summer maize/winter wheat system in the study area were from 119 to 221, − 601 to − 595, and − 433 to − 291 g C m − 2 , respectively (the net biological production (NBP) were − 709 to − 437, 220–303, and − 496 and − 260 g C m − 2 , respectively). Notably, the average carbon emission rate of the summer maize/winter wheat agroecosystem in the Guanzhong Plain, considering the carbon output at harvest is 386.2 g C m − 2 year − 1 . Therefore, this study may guide assessment of carbon balance of agroecosystems in dry sub-humid regions, and provide a strong reference for achieving carbon neutrality in local agroecosystems. • Winter wheat dominates net carbon exchange in rotation agroecosystem. • Net radiation and LAI are the dominant controlling factors of carbon balance. • Carbon was exported at an average rate of 386.2 gC m − 2 year − 1 owing to grain removal. [ABSTRACT FROM AUTHOR]

Water scarcity adversely affects the growth and yield of summer maize in the semi-arid region of Northwest China, and the application of irrigation technology to save water is an effective method for sustainable agricultural development in the area. In order to evaluate the potential of different drip methods for increasing grain yield and water productivity (WP), a 2-year (2018–19) field experiments was conducted to study the effects of various drip irrigation methods on the biomass accumulation and translocation and grain filling progress. The experiment involved three drip irrigation methods: conventional surface drip irrigation (CDI), subsurface drip irrigation (SDI) and alternate surface and subsurface drip irrigation in the soil vertical profile (ADI). The results showed that the ADI treatment had the highest above-ground accumulation of biomass at the maturity stage. However, no statistically significant differences were observed in all the treatments. The contribution of post-silking biomass to grain yield was ADI > SDI > CDI. Based on the two-year average analysis of data, the contribution of post-silking biomass to the grain yield in ADI was 3.6% and 7.0% higher than that in SDI and CDI, respectively. The maximum grain filling rate and the mean grain filling rate were the highest in the ADI, followed by SDI with CDI as the lowest. The active grain filling period and effective grain filling time were the highest under ADI and the lowest under CDI. There was a positive correlation between the active grain filling period and effective grain filling time. The ADI treatment decreased the grain number per spike but significantly increased the kernel weight. Two years of mean data demonstrated that the grain yield of the ADI was 6939.5 kg ha−1, which corresponded to increases of 4.8% and 13.3% from 6625.0 and 6126.5 kg ha−1 for SDI and CDI, respectively. For WP, the difference between treatments followed a similar pattern in 2018 and 2019, i.e., the ADI was significantly higher than the SDI, while the SDI was significantly higher than the CDI. Taken together, in addition to its potential for saving water, ADI has the additional advantage of promoting yield. Furthermore, the findings can contribute to a better understanding of the mechanism of biomass accumulation and grain filling process responses to drip irrigation methods. ● Three drip irrigation methods were tested in semiarid regions of Northwest China. ● Alternate drip irrigation in soil vertical profile (ADI) is an effective method. ● ADI reduced the grain number per spike but significantly increased the grain weight. ● The ADI treatment obtained the highest grain yield and water productivity. [ABSTRACT FROM AUTHOR]