Plastic Film-mulched Ridge Research Articles

Plastic film-mulched ridges and straw-mulched furrows increase soil carbon sequestration and net ecosystem economic benefit in a wheat-maize rotation

The application of soil mulching has been widely used to increase crop production in arid, semi-arid, and sub-humid areas, with plastic film-mulched ridges and straw-mulched furrows (RFPS) proving to be more effective as compared with other soil mulching practices. However, few research studies have comprehensively assessed the impacts of RFPS on greenhouse gas (GHG) emissions, grain yield, net ecosystem carbon budget (NECB), and net ecosystem economic budget (NEEB) compared against the single practices of either plastic film mulching or straw mulching. A three-year field experiment was conducted on a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation field in the southern Loess Plateau, China. Four treatments were evaluated: (1) conventional flat planting without mulching (CK), (2) flat planting with plastic film mulching (PM), (3) flat planting with straw mulching (SM), and (4) RFPS. All mulching practices significantly increased wheat and maize yields as well as the seasonal cumulative carbon dioxide (CO2) emissions from soil respiration (Rs) and ecosystem respiration (Re) compared with CK. RFPS had the greatest annual grain yield and the greatest Rs for wheat seasons. The average annual NECB values for CK and PM were − 1.47 and − 1.05 Mg CO2-eq ha−1 yr−1, respectively, where the negative values indicated that the soil in CK and PM acted as a carbon (C) source. SM and RFPS acted as C sinks because of the straw C input, having average annual NECB values of 1.46 and 1.74 Mg CO2-eq ha−1 yr−1, respectively. PM, SM, and RFPS significantly increased the average annual NEEB by 31.4%, 70.5%, and 60.3%, respectively, compared with CK. Although RFPS had greater C input and grain yield income, it also had greater Rs, harvest removal C loss, and agricultural input costs, resulting in similar NECB and NEEB to what was observed with SM. Considering that the greatest grain yields were obtained with RFPS, this production practice should be a promising method for maintaining greater, more stable crop production, while increasing soil C sequestration and NEEB for the wheat-maize cropping system in dry semi-humid regions such as the southern Loess Plateau of China.

Long-term straw mulching with nitrogen fertilization increases nutrient and microbial determinants of soil quality in a maize–wheat rotation on China's Loess Plateau

Mulching and nitrogen (N) fertilization are essential to increase crop yields in semiarid drylands. However, their long-term effects on soil physicochemical properties, extracellular enzyme activities, microbial community structure, and therefore soil quality via developing a soil quality index (SQI) remain largely unexplored. Hence, we analyzed soils after 14 years of mulching (CT, no mulch; RF, plastic film-mulched ridges and straw mulched-furrows; SM, straw mulching) and N fertilization (0, 120 and 240 kg ha−1) treatments in a maize–wheat rotation on China's Loess Plateau. Compared with CT, RF and SM significantly increased soil moisture content (SMC), organic carbon (SOC), phosphatase, and total phospholipid fatty acids (PLFAs). Compared with RF, SM increased SOC, total N, available phosphorus (AP), available potassium (AK), β-glucosidase, N-acetyl-glucosaminidase (NAG), peroxidase, and cellobiohydrolase, gram-negative bacteria (G−), and fungi. Consequently, the SQI was highest in SM (0.698), followed by RF (0.642) and CT (0.620). Nitrogen fertilization significantly increased total N, NO3−, microbial biomass N, α-glucosidase, NAG, total PLFAs, and G−, but caused a significant decline in pH, AP, AK, and the G+:G− ratio. Averaged across N-fertilizations, the SQI was ranked N240 (0.680) > N120 (0.650) > N0 (0.630). Redundancy analysis showed that SOC was closely associated with enzyme activities, whereas NO3−, SOC, and SMC were the key variables regulating microbial community composition. Structural equation model indicated that mulching and N fertilization strongly and positively affected SQI by regulating soil available N, P, and K, enzyme activities, and microbial communities, and the total effect of mulching (0.62) on SQI was greater than that of N addition (0.34). Collectively, the highest SQI observed in the SM + N240 treatment suggested that straw mulch, rather than plastic-film mulch, combined with high N addition could be a sustainable land management practice that improves soil quality in semiarid dryland farming systems.

Mechanism analysis and performance improvement of mechanized ridge forming of whole plastic film mulched double ridges

In order to achieve high-performance and mechanization construction standard of whole plastic mulched double ridge seedbed, and to meet its forming process and corresponding agronomic requirements of the mechanized double ridge seedbed, the key working parameters such as the speed of rotary blade group, the thickness of upturned sod and the power consumption of rotary blade group under different parameters were analyzed based on related working performance in ridge forming. Also, the test factors and their range of values were finally determined in this study. Discrete element method (DEM) simulation was applied in the numerical simulation of the mechanized ridge forming process of whole plastic mulched double ridges, and the ridge forming effect and digging resistance variation characteristics of different types of shovels were compared. Taking the forward speed of the combined machine, the penetration angle of the arc-shaped shovel and the depth of rotary tillage as independent variables, and the qualified rate of seedbed tillage as the response value, the mathematical model between the test factors and the qualified rate of the seedbed tillage was established, to explore the influence sequence of the factors on the qualified rate of seedbed tillage, and obtained the following optimal working parameters of the ridge forming device: the advancing velocity of the combined machine of 0.50 m/s, penetration angle of the arc-shaped shovel of 31°, rotary tillage depth of 140 mm, and average qualified rate 95.20% of seedbed tillage in corresponding simulation verification test. Field test showed that the average qualified rate of seedbed tillage in ridge forming device was 93.60%, which was close to that of the simulation results. The actual working condition of the sample machine was basically in line with the simulation process and could relatively precisely reflect the mechanized ridge forming mechanism of whole plastic double ridges. The results showed that the established DEM model and its parameter setting were relatively accurate and reasonable. Keywords: whole plastic film mulched double ridges, mechanized ridge forming, DEM, numerical simulation, parameter optimization DOI: 10.25165/j.ijabe.20201305.5747 Citation: Dai F, Song X F, Zhao W Y, Shi R J, Zhang F W, Zhang X K. Mechanism analysis and performance improvement of mechanized ridge forming of whole plastic film mulched double ridges. Int J Agric & Biol Eng, 2020; 13(5): 107–116.

Effects of different film mulching methods on soil water productivity and maize yield in a semiarid area of China

Film mulching has been used widely to improve field productivity in rainfed agricultural ecosystems in semiarid areas of China. During 2013–2016, we evaluated the effects of different film mulching methods on soil water, water productivity, crop yield, and economic benefits in a semiarid area of southern Ningxia, China. Five treatments were tested: (i) a control method consisting of conventional flat planting without mulching (CK); (ii) alternate mulching and bare rows without ridges and planting in mulched rows (P); (iii) maize planted in furrows separated by consecutive plastic film-mulched ridges (S); (iv) maize planted in furrows separated by alternating large and small plastic film-mulched ridges (D); and (v) maize, planted in furrows with large plastic film-mulched ridges alternating with flat plastic film-mulched spaces (R). After four years of continuous treatment, the results indicated that D and S treatments significantly increased soil water content at depths of 0–200 cm during the early growth stage, but the increases in the soil water content were lower later in the maize growth process. The grain yield increases were affected by the different hydrothermal conditions in various years. On average, mulching increased grain yield by 31.33 %, and biomass accumulation by 22.48 %. Across four seasons, film mulching significantly (P < 0.05) increased water use efficiency and precipitation use efficiency, especially in D by 34.56 % and 43.09 %, and S by 35.25 % and 42.79 %, respectively. Mulching changed the crop water consumption characteristics, and resulted in higher crop water productivity due to an improved hydro-thermal balance, especially during the vegetative (30–90 days) and pre-reproductive (90–120 days) growth stages, which may account for yield increase effects in this system. In addition, the results suggested that the mulching system achieves higher economic returns than CK, especially the S treatment (7538 ¥ ha−1, representing an average of 29.19 % higher than CK.). The S treatment could serve as a promising adaptive management method for increasing maize productivity to cope with food security and climate change in this semi-arid area with limited and erratic precipitation.

Stratification of soil organic C, N and the C:N ratio as affected by different plastic film mulching modes in a semiarid region of China

The soil degradation caused by plastic film mulching tillage in rain-fed areas of north-west China is known to affect sustainable and stable crop yields because of major losses of soil organic carbon (SOC) and nutrients. To evaluate the effects of different plastic film mulching modes on SOC and total nitrogen (STN) sequestration capacity in loessic soil, we investigated the effects of different plastic film mulching on SOC, STN, and the soil C:N ratio in semiarid areas of southern Ningxia for a 4-year period (2013–2016). Five treatments were tested: (i) the control, conventional flat planting without mulching (CK); (ii) alternating mulching and bare rows without ridges and planting in mulched rows (P); (iii) furrow planting of maize, separated by consecutive plastic film-mulched ridges (S); (iv) furrow planting of maize, separated by alternating large and small plastic film-mulched ridges (D); and (v) furrow-flat planting of maize with a large plastic film-mulched ridge alternating with a flat plastic film-mulched space (R). In the final experimental year (2016), the results showed that the mean soil bulk density at 0–60 cm depth had decreased with film mulching treatments by 2.82%, 5.90% (P &amp;lt; 0.05), 7.29% (P &amp;lt; 0.05), and 9.46% (P &amp;lt; 0.05) respectively, compared with CK. Film mulching increased the concentration of SOC and STN, which were ranked in order S &amp;gt; R/D &amp;gt; P &amp;gt; CK; however, there was no significant increase with the storage of SOC and STN. The mean soil C:N ratio was higher with mulching treatment, i.e. 2.91% (P &amp;gt; 0.05) higher than CK in 0–60 cm depth. Mulching treatments significantly (P &amp;lt; 0.05) increased the stratification ratio (SR) of SOC and soil C: N ratio from the surface (0–20 cm) to all depths compared with CK, i.e. the SR of SOC at the 0–20:20–40 cm depth significantly (P &amp;lt; 0.05) increased with D, R, S, and P by 14.81%, 9.47%, 14.18%, and 9.51% respectively, compared with CK.

Fate and transport of urea-N in a rain-fed ridge-furrow crop system with plastic mulch

A better understanding of the fate and transport of fertilizer nitrogen (N) is critical to maximize crop yields and minimize negative environmental impacts. Plastic film mulching is widely used in drylands to increase soil water use efficiency and crop yields, but the effects on fertilizer N use efficiency need to be evaluated. A field experiment with 15N-urea (260 kg N ha−1) was conducted to determine the fate and transport of fertilizer N in a ridge-furrow system with plastic film mulched ridge (Plastic), compared with a flat system without mulching (Open). In the Plastic, the 15N-urea was applied to the ridge only (Plastic-Ridge), or to the furrow only (Plastic-Furrow). Maize grain yield and net economic benefit for Plastic were significantly higher (by 9.7 and 8.5%, respectively) than those for Open. Total plant 15N uptake was 72.5% greater in Plastic compared with Open, and 15N was allocated mostly to the grain. Losses of the applied urea-N were 54.5% lower in Plastic and much more residual 15N was recovered in 0–120 cm soil compared with Open (42.7 and 26.8% of applied 15N, respectively). Lateral N movements from furrow to ridge and from ridge to furrow were observed and attributed to lateral movement of soil water due to microtopography of ridges and furrows and uneven soil water and heat conditions under mulching and plant water uptake. The ridges were the main N fertilizer source for plant uptake (96.5 and 3.5% of total N uptake in Plastic from ridge and furrow, respectively) and the furrow was the main source of N losses (78.6 and 21.4% of total N losses in Plastic from furrow and ridge, respectively). Gas emissions, especially ammonia volatilization was probably the main N loss in furrow. Thus, appropriately localized N application – into the ridges, and management strategies should be designed for Plastic to maximize N use efficiency by crops, decrease N gas losses and maintain sustainable agricultural systems in drylands.

Ridge-furrow with plastic film and straw mulch increases water availability and wheat production on the Loess Plateau

Mulching is critical for increasing water availability and hence winter wheat production in dryland farming systems. A two-year study was conducted to assess the effects of mulches on soil water storage (SWS), temperature, water use efficiency (WUE) and yields of winter wheat on the Loess Plateau. Four treatments were examined: conventional flat planting (CK), straw mulch (FPS), transparent plastic film mulch (FPP) and ridge-furrow with plastic film-mulched ridge and straw-mulched furrow (RFPS). Compared with CK, RFPS greatly increased SWS from 0–60 cm, FPP increased SWS from 0–40 cm, and FPS slightly increased SWS from 0–60 cm; however, FPP significantly (P < 0.05) decreased SWS from 61–100 cm. RFPS and FPP increased soil temperatures in cold seasons relative to CK, especially in RFPS (2.0–2.3 °C). Meanwhile, the rate of soil temperature increase was greater in RFPS and FPP than in CK but was lower in FPS. Mean yields were significantly increased in RFPS (56.78%), FPP (44.72%) and FPS (9.57%), and WUE was significantly increased in RFPS (44.04%) and in FPP (37.50%) compared with CK (P < 0.05). We conclude that ridge-furrow planting with plastic film-mulched ridge and straw-mulched furrow has a good potential for raising winter wheat production on the Loess Plateau.

Effects of long-term cultivation practices and nitrogen fertilization rates on carbon stock in a calcareous soil on the Chinese Loess Plateau

Soil organic carbon (SOC) and soil inorganic carbon (SIC) are important C pools in the Loess Plateau of Northwest China, however, variations of SOC and SIC stocks under different cultivation practices and nitrogen (N) fertilization rates are not clear in this area. A long-term field experiment started in June 2003 was conducted to investigate the SOC and SIC stocks in a calcareous soil of the Chinese Loess Plateau under four cultivation practices, i.e., fallow (FA), conventional cultivation (CC), straw mulch (SM), and plastic film-mulched ridge and straw-mulched furrow (RF), in combination with three N fertilization rates, i.e., 0 (N0), 120 (N120), and 240 (N240) kg N/hm2. Results indicate that the crop straw addition treatments (SM and RF) increased the contents of soil microbial biomass C (SMBC) and SOC, and the SOC stock increased by 10.1%–13.3% at the upper 20 cm soil depth in comparison to the 8-year fallow (FA) treatment. Meanwhile, SIC stock significantly increased by 19% at the entire tested soil depth range (0–100 cm) under all crop cultivation practices in comparison to that of soil exposed to the long-term fallow treatment, particularly at the upper 60 cm soil depth. Furthermore, moderate N fertilizer application (120 kg N/hm2) increased SOC stock at the upper 40 cm soil depth, whereas SIC stock decreased as the N fertilization rate increased. We conclude that the combined application of crop organic residues and moderate N fertilization rate could facilitate the sequestrations of SOC and SIC in the calcareous soil.

Effects of Ridge-Furrow System Combined with Different Degradable Mulching Materials on Soil Water Conservation and Crop Production in Semi-Humid Areas of China.

In China, the ridge-furrow water conservation planting (RC) system is advantageous for improving crop yields and rainwater use efficiency. In RC planting system, plastic film-mulched ridges are employed for water harvesting while the furrows serve as infiltration and planting belts. To optimize the RC system and to overcome problems due to the lack of water in semi-humid areas at risk of drought, we mulched the furrows with 8% biodegradable film (RCSB), liquid film (RCSL), or no mulching in the furrows (RCSN), while conventional flat planting (CF) was employed as the control. After 4 year (2007–2010) consecutive field study, the results showed that the soil water storage level in the 0–100 cm layer with four treatments was ranked as follow: RCSB > RCSL > RCSN > CF, while the RCSB and RCSL were 26.3 and 12.2 mm greater than RCSN, respectively. Compared with CF, the average soil temperature was significantly (P < 0.05) higher by 3.1, 1.7, and 1.5°C under the RC planting treatments (RCSB, RCSL, and RCSN) during each year, respectively. The average ET rate of RC treatments were all lower than CF in each experimental year, and the average decreased by 8.0% (P < 0.05). The average yields with RCSB, RCSL, and RCSN increased by 2,665, 1,444, and 1,235 kg ha−1, respectively, and the water use efficiency (WUE) increased by 51.6, 25.6, and 21.1%, compared with CF. RCSB obtained the highest economic benefit, the average net income was higher than CF by 4,020 Yuan ha−1. In conclusion, we found that RC planting with biodegradable film mulching in the furrows is the best cultivation pattern in the semi-humid areas of China in terms of both environmental and economic benefits.

Coupled effects of mulching and nitrogen fertilization on crop yield, residual soil nitrate, and water use efficiency of summer maize in the Chinese Loess Plateau.

Appropriate water-saving and nitrogen management strategies are critical for achieving sustainable agricultural development in dry sub-humid areas of the Chinese Loess Plateau. The present study was conducted in 2004, 2005, 2008, and 2012 based on a long-term field experiment and aimed to investigate the coupled impacts of mulching and N fertilization on maize yield, water use efficiency (WUE), and residual soil nitrate (RSN) accumulated in the soil profile (0-200cm). The results demonstrated that mulch is conducive to increasing summer maize yield. The plastic film-mulched ridge and straw-mulched furrow (RF) treatment significantly increased maize yield across the studied period, while the straw mulch (SM) treatment did not significantly increase maize yield until the third experimental year. Compared with SM, the RF treatment showed more significant and positive effects on maize yield, WUE, and RSN accumulated in the 0-200cm soil depth. N fertilization significantly increased maize yield and WUE, but no significant differences were observed when 120 and 240kg N ha-1 were applied. The N240 treatment was characterized by relatively high NO3--N accumulation in 0-200cm soil depth and low ratios of soil nitrate in the upper to the lower soil layers, indicating a considerable potential for NO3--N leaching. Averaged across years, economic optimum N fertilizer rates (Nops) were 154, 148, and 150kg N ha-1 for the no mulch, RF, and SM treatments, respectively. This suggested that 25.8-51.2% of N rate can be reduced while maintaining an acceptably high maize yield. Additionally, understanding NO3--N depth distribution in 0-100cm soil profile can adequately predict and represent the characteristics of NO3--N accumulated in the 100-200cm and 0-200cm soil layers because of their significant correlations, thus saving time and money. In conclusion, the practice of RF combined with properly reduced farmers' N rate (~150kg N ha-1) is the preferred option for maize production in the Chinese Loess Plateau, and further research is required to investigate the effects of mulching on summer maize under Nop conditions.

Effects of tillage, mulching and N management on yield, water productivity, N uptake and residual soil nitrate in a long-term wheat-summer maize cropping system

A thorough understanding of coupled effects of soil management (tillage), mulch and N rate on the wheat-maize system is crucial for achieving sustainable agriculture in the southern Loess Plateau of China. This study was based on a 12-year (2003–2015) field experiment and aimed to evaluate the impact of three wheat-maize systems (S) which varied in terms of tillage, mulch, wheat row spacing and irrigation management (CT, conventional tillage with no mulch; RFM, ridge-furrow with plastic film-mulched ridges and straw-mulched furrows; CTM, conventional tillage with straw mulch) combined with N fertilizer rates (0, 120 and 240kgNha−1) on crop yield, water productivity (WP, kg grain per kg of water input), N uptake, residual soil nitrate (RSN) and soil physicochemical properties. Results demonstrated that RFM significantly increased maize yield in comparison with CT in all 12 years, while CTM increased yield in comparison with CT from year 3 onwards. By contrast, wheat yield was not strongly influenced by RFM and CTM from 2004 to 2012 (except for 2008). Maize yields of RFM were significantly higher than those of CTM from the third year onwards. Compared with CT, the other two practices, and more so RFM, showed beneficial effects on crop yield, the amount of stored water, WP, N uptake and RSN. N fertilization significantly increased crop yield, WP and N uptake, while no significant difference was observed between the N120 and N240 treatments. Notably, considerable buildup of RSN to∼490kgNha−1 at maize harvest and ∼340kgNha−1 at wheat harvest were observed in 0–200cm soil depth when 240kgNha−1 was applied. These results suggest that the conventional N rate of 240kgNha−1 is excessive, and risks serious contamination of the groundwater as a result of NO3−-N leaching. The N120 treatment was characterized with considerably lower RSN accumulation after harvest, while maintaining crop yield. Thus, we concluded that the RFM practice with 120kgNha−1 application could reduce irrigation water and fertilizer inputs and increase crop land and water productivity, and is a promising strategy for developing sustainable agriculture in the southern Loess Plateau and other areas with similar climate and cropping systems.

Mulching affects photosynthetic and chlorophyll a fluorescence characteristics during stage III of peach fruit growth on the rain-fed semiarid Loess Plateau of China

In this study, we compared the soil water content of plastic film mulched ridge with furrows (PFM) and straw mulched (SM) and unmulched (clean tillage, CT) peach (Prunus persica L.) orchard soil on the rain-fed semiarid Loess Plateau of China during the final stage of rapid fruit growth (stage III) in 2011 and 2012. Analyses were focused on measurements of fast chlorophyll a fluorescence (ChlF), photosynthetic performance, fruit yield and quality. Compared with the CT water management method, PFM and SM significantly increased the soil water content (P<0.05) by 14.5% and 19.5% in stage III, respectively. Both mulching methods increased the fruit yield (∼28%) with no change in fruit quality compared to the CT method. This result was supported by the analysis of the daily average photosynthetic rate (PN) showed that PN was improved from 11.4 (CT) to 13.1 (PFM) and 12.2μmolm−2s−1 (SM); these daily average photosynthetic rates were confirmed by the response curve analysis. Furthermore, the ChlF analyses uncovered major functional differences between the mulched and unmulched leaves at midday: lower connectivity among the photosystem II decreased the number of electron carriers and facilitated the dissipation of excess excitation energy to minimize the potential damage caused by CT drought stress. Nevertheless, the structural integrity and stability of PSII were largely maintained, as reflected by the recovering of the photosynthetic activity after mid-day.

Mulching increases water-use efficiency of peach production on the rainfed semiarid Loess Plateau of China

We examine the water-use balance, fruit yield and water-use efficiency of five-year-old peach trees with two different mulching systems: plastic film mulched ridge, with furrows (PFM) and straw mulched (SM). Compared with the clean tillage (CT) water management method, PFM increased, and SM significantly decreased, the soil temperature (P<0.05). Both mulching systems increased the gravimetric soil water content (1.9–2.9%) with a reduction in the average annual evapotranspiration (ET) of 82.5mm and 49.3mm through SM and PFM, respectively. The water-use efficiency (WUE) was improved from 5.7 (CT) to 8.1 (PFM) and 9.0kgm−3 (SM), resulting in a reduction in ET and an increase in fruit yield from 25.2 (CT) to 32.2 (PFM) and 32.5tha−1 (SM). Thus, both mulching systems could serve as models for peach production in semiarid rainfed areas, due to the high soil water content during bloom and fruit expansion.

Effects of a ridge-furrow micro-field rainwater-harvesting system on potato yield in a semi-arid region

To evaluate the effects of mulching and ridge and furrow widths on soil temperature and moisture, crop growth and yield, and water use efficiency (WUE), a series of field experiments were conducted in a potato field in Inner Mongolia, China. In 2009 and 2010, four treatments (flat plot without mulching (CK), plastic film mulched ridge (MR), MRF (plastic film mulched ridge and furrow (MRF), and non-mulched (NM0.5)) were conducted on the same widths of ridge (0.5m) and furrow (0.5m), and two additional non-mulching treatments (1.0m ridge and furrow width (NM1.0), and 1.5m ridge and furrow width (NM1.5)) were tested in 2011 and 2012. The results indicated that mulching practices increased topsoil temperature compared to non-mulching treatments at the emergence stage. Compared to CK, the soil water storage in furrows was increased by 10.2mm on average in 2009 for the MRF treatment, 8.1mm and 15.1mm in 2011, and 14.0mm and 21.2mm in 2012 for NM1.0 and NM1.5, respectively, and plant leaf area index and dry biomass values during the potato growth stage were also increased. The MR treatment produced greater effects on crop productivity than NM0.5, and increased total yield and marketable yield by 21.4% and 36.3% compared to CK in 2010. Of three non-mulching treatments (i.e., NM0.5, NM1.0, and NM1.5), the NM1.0 treatment produced the highest total yield and marketable yield; compared to CK, the WUE, total yield, and marketable yield were increased by 12.7%, 8.2%, and 52.0% in 2011, and 23.4%, 16.4%, and 81.0% in 2012, respectively.

垄沟覆膜栽培冬小麦田的土壤呼吸

通过大田试验研究了垄沟覆膜栽培条件下冬小麦生长过程中土壤呼吸规律。结果表明,垄沟覆膜栽培条件下垄脊土壤呼吸速率高于平作栽培,而垄沟部土壤呼吸速率小于平作。冬小麦生育期内垄脊平均呼吸速率为(2.06±0.44) μmol CO₂·m^-2·s^-1,垄沟为(0.75±0.11) μmol CO₂·m^-2·s^-1,而平作栽培为(1.14±0.20) μmol CO₂·m^-2·s^-1。土壤呼吸季节变化显著,越冬期低,夏季高。不同生育期土壤呼吸日变化规律不同,越冬前和返青期土壤呼吸与土壤温度成正相关,随着土壤温度的升高而增加,呈单峰曲线;拔节期后垄脊部的土壤呼吸日变化明显,呈现双峰曲线;而平作和垄沟的土壤呼吸速率平稳,没有明显峰值。5 cm土壤温度与土壤呼吸之间的相关性最好。在一定范围内(<24-31 ℃),土壤呼吸随着温度的增加而增加,温度过高反而会抑制土壤呼吸速率。土壤呼吸<em>f(R)</em>与5 cm土壤温度之间的关系可以用二次函数表示;5 cm土壤温度<em>T</em>和土壤含水量<em>W</em>的交互效应可用函数:<em>f(R)=a(bT²+cT)(1+d</em>ln<em>(2W)/T)+e</em>表示。垄沟覆膜栽培显著改变了冬小麦田的土壤呼吸作用。;The objectives of this experiment were to study the effects of a plastic mulched-ridges and unmulched furrows (PMRF) cropping system on soil respiration. The experiment field was planted to winter wheat. Soil CO₂ emission was determined with an SR1LP chamber (Qubit Inc., Canada) between October 2010 and June 2011. The data suggested that soil CO₂ emission in the plastic film mulched-ridge (RM) was greater than that in an unmulched, smooth field (FC). Furthermore, CO₂ emission rates from the plastic film-mulched ridges were greater than those from the unmulched furrows (FU). The mean soil CO₂ fluxes were (1.14±0.20) μmol CO₂·m^-2·s^-1 from the unmulched, smooth field, (2.06±0.44) μmol CO₂·m^-2·s^-1 from the plastic film-mulched ridge, and (0.75±0.11) μmol CO₂·m^-2·s^-1 from the unmulched furrow. There were significant seasonal variations in soil respiration. Soil respiration was lowest during the winter when the wheat was in the seedling stage and highest during the summer when the wheat was mature. Diurnal CO₂ emissions from plastic film-mulched ridges, unmulched furrows, and unmulched, smooth fields followed similar patterns during the winter and early spring. Specifically, CO₂ emissions increased during the morning, reached a peak around noon, and then decreased in the afternoon. In contrast, there were differences in diurnal CO₂ emissions among the treatments after jointing stage. There was a double peak in soil CO₂ emission from plastic film-mulched ridges. However, CO₂ emissions from unmulched furrows and unmulched, smooth fields remained steady throughout the day. Soil respiration was significantly correlated with soil temperature at the 5 cm depth. Soil respiration increased as the soil temperature increased from 10 to 24-31 ℃. Soil respiration decreased at soil temperatures >31 ℃. The effect of soil temperature on soil CO₂ emission was best described by a quadratic function, whereas the interactive effects of soil temperature <em>(T)</em> and soil moisture <em>(W)</em> on soil CO₂ emission were best described by the following equation:<em> f(R)=a(bT²+cT)(1+d</em>ln<em>(2W)/T)+e</em>. The soil respiration in winter wheat field was changed with the plastic mulched-ridges and unmulched furrows practice.

Effect of water saving management practices and nitrogen fertilizer rate on crop yield and water use efficiency in a winter wheat–summer maize cropping system

Deficit irrigation (DI) is a water-saving irrigation strategy in which irrigation water is applied at amounts less than full crop-water requirements. Some researchers have suggested that greater increases in water use efficiency (WUE) could be realized if DI was used in combination with water conservation or rainwater harvesting techniques. The objective of this six-year field study was to determine the effect of DI in combination with straw mulch (SM) or plastic film-mulched ridge and straw-mulched furrows (RF) on grain yield and WUE in a winter wheat–summer maize rotation. Interactive effects between the water-saving management practices and N fertilizer rate were also investigated. Results indicated that maize yields in the RF + DI and SM + DI treatments were as much as 1.6 times those in the DI and conventional furrow irrigation (CFI) treatments. Over the six-year study, total maize yield in the RF + DI treatment was 5580 kg/ha more than in the CFI treatment and 6500 kg/ha more than in the DI treatment. Wheat yields in the RF + DI and SM + DI treatments were similar to the CFI treatment but slightly more than in the DI treatment. At harvest, there was no significant difference in water storage in the 0–200 cm soil profile among the RF + DI, SM + DI, DI, and CFI treatments. Nitrogen fertilizer application significantly increased maize and wheat yield compared to the unfertilized treatment; however, there was no further yield response when the N application rate exceeded 120 kg N/ha. In summary, these results indicated that DI in combination with SM or RF practices increased crop yield and WUE in the winter wheat–summer maize crop rotation. Compared to CFI practices, the SM + DI and RF + DI practices reduced the amount of irrigation water applied over a six-year period by about 350 mm.

Control of Strawberry Anthracnose by Irrigation into Plastic Film Mulched Ridge of Mother Plants in Plastic Greenhouses

Control of Strawberry Anthracnose by Irrigation into Plastic Film Mulched Ridge of Mother Plants in Plastic Greenhouses