Maize/peanut rotation intercropping improves ecosystem carbon budget and economic benefits in the dry farming regions of China.

Monoculture is widely practiced to increase crop productivity, but long-term adaptation has drawbacks as it increases the depletion of soil nutrients and reduces soil quality, especially in dryland areas. Conversion from traditional maize monoculture to intercropping improves sustainable production. However, maize/peanut intercropping, especially rotation of planting strips impacts of maize/peanut intercropping in dryland on carbon (C) budgets and economic benefits remain unclear. In this study, a 5-year field experiment was conducted to evaluate the influence of maize/peanut intercropping with rotation of planting strips on soil health, indirect CO2-eq greenhouse gas emissions, and ecosystem C inputs. Four intercropping treatments viz. maize monoculture, peanut monoculture, maize/peanut intercropping, and maize/peanut rotation-intercropping were tested from 2018 to 2022. Maize/peanut rotation intercropping significantly improved the land equivalent ratio followed by intercropping and monoculture. Rotation-intercropping also improved economic benefits over intercropping and monoculture which were mainly associated with increased peanut yield where the border rows contributed the maximum, followed by the middle rows. Moreover, rotation-intercropping significantly increased the soil organic C and nitrogen (N) content. Rotation-intercropping decreased indirect CO2-eq greenhouse gas emissions and ecosystem C inputs by 3.11% and 18.04%, whereas increased ecosystem C outputs and net ecosystem C budget by 10.38% and 29.14%, respectively, over the average of monoculture. On average for intercropping and monoculture, rotation-intercropping increased ecosystem C emission efficiency for economic benefits by 51.94% and 227.27% in 2021 and 2022, respectively, showing the highest C utilization efficiency than other treatments. In the long run, maize/peanut rotation-intercropping can be practiced in dryland agriculture to achieve sustainable agriculture goals.

Can deep fertilization in spring maize fields improve soil properties and their distribution in soil profile?

Deep fertilization strategy has been proven to be an important fertilizer management method for improving fertilizer utilization efficiency and crop yield. However, the relationship between soil chemical and biochemical characteristics and crop productivity under different fertilization depth patterns still needs comprehensive evaluation. Field tests on spring maize were therefore carried out in the Loess Plateau of China for two successive growing seasons from 2019 to 2020. Four distinct fertilization depths of 5 cm, 15 cm, 25 cm, and 35 cm were used to systematically investigate the effects of fertilization depth on soil physicochemical parameters, enzyme activity, and biochemical properties. The findings demonstrated that although adjusting fertilization depths (D15, D25) did not significantly affect the soil organic carbon content, they did significantly improve the soil chemical and biochemical characteristics in the root zone (10-30 cm), with D25 having a greater influence than D15. Compared with D5, the total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), Olsen-P, dissolved organic carbon, and nitrogen (DOC and DON) in the root zone of D25 significantly increased by 12.02%, 7.83%, 22.21%, 9.56%, 22.29%, and 26.26%, respectively. Similarly, the urease, invertase, phosphatase, and catalase in the root zone of D25 significantly increased by 9.56%, 13.20%, 11.52%, and 18.05%, while microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP) significantly increased by 18.91%, 32.01% and 26.50%, respectively, compared to D5. By optimizing the depth of fertilization, the distribution ratio of Ca2-P and Ca8-P in the inorganic phosphorus components of the root zone can also be increased. Therefore, optimizing fertilization depth helps to improve soil chemical and biochemical characteristics and increase crop yield. The results of this study will deepen our understanding of how fertilization depth influence soil properties and crop responses.

Environment and agricultural practices regulate enhanced biochar-induced soil carbon pools and crop yield: A meta-analysis.

Using biochar in agriculture to enhance soil carbon storage and productivity has been recognized as an effective means of carbon sequestration. However, the effects on crop yield and soil carbon and nitrogen can vary depending on environmental conditions, field management, and biochar conditions. Thus, we conducted a meta-analysis to identify the factors contributing to these inconsistencies. We found that biochar application significantly increased soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), easily oxidized carbon (EOC), particulate organic carbon (POC), total nitrogen (TN), and the C:N ratio in topsoil (0-20 cm) and crop yields. Biochar was most effective in tropical regions, increasing SOC, Soil TN, and crop yield the most, with relatively moderate pyrolysis temperatures (550-650 °C) more conducive to SOC accumulation and relatively low pyrolysis temperatures (<350 °C) more conducive to increasing soil carbon components and crop yields. Biochar made from manure effectively increased soil carbon components and TN. Soil with low fertility (original SOC < 5 g kg-1; original TN < 0.6 g kg-1), coarse texture, and acidity (pH < 5.5) showed more effective results. However, biochar application rates should not be too high and should be combined with appropriate nitrogen fertilizer. And biochar application had long-term positive effects on soil carbon storage and crop yield. Overall, we recommend using small amounts of biochar with lower pyrolysis temperatures in soils with low fertility, coarse texture, and tropical regions for optimal economic and environmental benefits.

Suitable fertilization can improve maize growth and nutrient utilization in ridge-furrow rainfall harvesting cropland in semiarid area.

The ridge-furrow rainfall harvesting system (RFRH) improved the water shortages, and reasonable fertilization can promote nutrient uptake and utilization of crops, leading to better yield in semi-arid regions. This holds significant practical significance for improving fertilization strategies and reducing the application of chemical fertilizers in semi-arid areas. This field study was conducted to investigate the effects of different fertilization rates on maize growth, fertilizer use efficiency, and grain yield under the ridge-furrow rainfall harvesting system during 2013-2016 in semiarid region of China. Therefore, a four-year localization field experiment was conducted with four fertilizer treatments: RN (N 0 kg hm-2, P2O5 0 kg hm-2), RL (N 150 kg hm-2, P2O5 75 kg hm-2), RM (N 300 kg hm-2, P2O5 150 kg hm-2), and RH (N 450 kg hm-2, P2O5 225 kg hm-2). The results showed that the total dry matter accumulation of maize increased with the fertilizer application rate. The nitrogen accumulation was highest under the RM treatment after harvest, average increase by 1.41% and 22.02% (P<0.05) compared to the RH and RL, respectively, whereas the phosphorus accumulation was increased with the fertilizer application rate. The nitrogen and phosphorus use efficiency both decreased gradually with the fertilization rate increased, where the maximum efficiency was observed under the RL. With the increase of fertilizer application rate, the maize grain yield initially increased and then decreased. Under linear fitting, the grain yield, biomass yield, hundred-kernel weight, and ear-grain number all showed a parabolic trend with the increase of fertilization rate. Based on comprehensive consideration, the recommended moderate fertilization rate (N 300 kg hm-2, P2O5 150 kg hm-2) is suitable for the ridge furrow rainfall harvesting system in semiarid region, and the fertilization rate can be appropriately reduced according to the rainfall.

Is adding biochar be better than crop straw for improving soil aggregates stability and organic carbon contents in film mulched fields in semiarid regions? -Evidence of 5-year field experiment.

Plastic film mulching is used widely to increase crop yields in semiarid areas, but improving the soil fertility in film mulched fields is also important for achieving sustainable high yields in northwest of China. In this study, a completely randomized two-factor field design experiment was conducted in Pengyang, Ningxia, China during 2017-2021. In order to investigate the effects of plastic film mulching with straw/biochar addition on the soil aggregate characteristics, organic carbon content, and maize yield. Six treatments were established as follows: control (C), straw (S), biochar (B), plastic film mulching (F), plastic film mulching with added straw (FS) or biochar (FB). After 5 years of continuous production, each straw and biochar addition treatments significantly improved the soil aggregate distribution and stability, and the average aggregate content >0.25 mm increased significantly by 47.32%. Compared with the treatments without plastic film mulching, the mean weight diameter and geometric mean diameter of the soil particles increased by 9.19% and 4.15%, respectively, under the plastic film mulching treatments. The organic carbon content of the 0-60 cm soil layer increased significantly under each straw and biochar addition treatment compared with the without straw. The aggregate organic carbon contents under each treatment increased as the aggregate particle size increased, where the straw and biochar addition treatments significantly increased the organic carbon content of the aggregates, whereas the contents decreased under the plastic film mulching treatments. The contributions of the soil aggregates >0.25 mm to the organic carbon contents of the 0-60 cm soil layer were significantly higher under FS (37.63%) and FB (56.45%) than F. Structural equation modeling showed that straw/biochar added, plastic film mulching, and a greater soil organic carbon content could significantly promote yield increases, where the straw and biochar addition treatments significantly increased the average maize by 14.6% on average. In conclusion, carbon input as straw, especially biochar, had a positive effect on improving the soil organic carbon content and maize yield under plastic film mulching farmland in a semiarid region.

Photosynthetic and yield responses of rotating planting strips and reducing nitrogen fertilizer application in maize-peanut intercropping in dry farming areas.

Improving cropping systems together with suitable agronomic management practices can maintain dry farming productivity and reduce water competition with low N inputs. The objective of the study was to determine the photosynthetic and yield responses of maize and peanut under six treatments: sole maize, sole peanut, maize-peanut intercropping, maize-peanut rotation-intercropping, 20% and 40% N reductions for maize in the maize-peanut rotation-intercropping. Maize-peanut intercropping had no land-use advantage. Intercropped peanut is limited in carboxylation rates and electron transport rate (ETR), leading to a decrease in hundred-grain weight (HGW) and an increase in blighted pods number per plant (NBP). Intercropped peanut adapts to light stress by decreasing light saturation point (Isat) and light compensation point (Icomp) and increasing the electron transport efficiency. Intercropped maize showed an increase in maximum photosynthetic rate (Pnmax) and Icomp due to a combination of improved intercellular CO2 concentration, carboxylation rates, PSII photochemical quantum efficiency, and ETR. Compare to maize-peanut intercropping, maize-peanut rotation-intercropping alleviated the continuous crop barriers of intercropped border row peanut by improving carboxylation rates, electron transport efficiency and decreasing Isat, thereby increasing its HGW and NBP. More importantly, the land equivalent ratio of maize-peanut rotation-intercropping in the second and third planting years were 1.05 and 1.07, respectively, showing obvious land use advantages. A 20% N reduction for maize in maize-peanut rotation-intercropping does not affect photosynthetic character and yield for intercropped crops. However, a 40% N reduction decreased significantly the carboxylation rates, ETR, Icomp and Pnmax of intercropped maize, thereby reducing in a 14.83% HGW and 5.75% lower grain number per spike, and making land-use efficiency negative.

Suitable Fertilizer Application Depth Enhances the Efficient Utilization of Key Resources and Improves Crop Productivity in Rainfed Farmland on the Loess Plateau, China.

Appropriate fertilizer application methods can help to improve crop yields. However, limited information is available regarding how different fertilizer application depths might affect crop production in dryland winter wheat-summer maize cropping in the Loess Plateau region of China. Therefore, we conducted field experiments in 2019-2020 and 2020-2021 to evaluate the effects of changing the fertilizer placement depth on summer maize (current crop) and winter wheat (succeeding crop) productivity, as well as the resource use efficiency and soil nitrate-nitrogen residue (SNR) level. Four fertilizer placement depths were tested comprising 5 cm (FD5), 15 cm (FD15), 25 cm (FD25), and 35 cm (FD35). The nitrogen uptake by summer maize in the two seasons was 10.0, 6.5, and 11.8% higher under FD15 compared with those under FD5, FD25, and FD35, respectively, because FD15 effectively increased the root length density, root surface area density, and rate of root bleeding sap. Due to the increased nitrogen uptake, the leaf area index, plant height, stem diameter, and accumulated dry matter were improved in summer maize. The interception of photosynthetically active radiation was 3.6, 3.7, and 5.9% higher under FD15 compared with those under FD5, FD25, and FD35, respectively. The summer maize grain yield increased by 13.9-22.4% under FD15 compared with the other treatments. In addition, the SNR in the deep soil (200-300 cm) was significantly lower under FD15 during the summer maize harvest (17.9-30.7%) compared with the other treatments. Moreover, FD15 increased the winter wheat (succeeding crop) grain yield (2.6-11.2%) and reduced the SNR in the 200-300 cm soil layer (8.8-16.8%) at the winter wheat harvest. The highest radiation use efficiency, precipitation use efficiency, and nitrogen use efficiency were obtained under FD15 in both summer maize and winter wheat. These results clearly suggest that depth fertilization of 15 cm enhanced the productivity and resource use efficiency for the current and subsequent crops in rainfed farmland in the Loess Plateau of China, as well as reducing the SNR in the deep soil to promote sustainable agricultural development. These findings provide a practical reference for optimizing fertilizer application management.

Farming practices and deficit irrigation management improve winter wheat crop water productivity and biomass through mitigated greenhouse gas intensity under semi-arid regions.

Understanding the greenhouse gas emissions mechanism from the agricultural soils is essential to reach an agricultural system with a lower impact on the environment. The cultivation practices in combination with deficit irrigation have been used in a dry-land farming system to modify the soil water status. However, few research works have been focused on plastic film with deficit irrigation regimes on global warming potential (GWP), greenhouse gas intensity (GHGI), and biomass productivity under simulated rainfall conditions. In the current study, a 2-year study was carried out in a rainproof mobile shelter to study the potential role of two cultivation practices (i.e., furrow with plastic mulching on ridges, RF; and conventional flat cultivation, TF) in combination with two deficit irrigation regimes (i.e., 150 and 75 mm) and three simulated rainfall (i.e., 1, 275 mm; 2, 200 mm; and 3, 125 mm). . We found that RF2150 treatment was more effective in improving the soil water content, soil respiration rate, and winter wheat production and significantly reduced (39.2%) the GHGI and GWP than TF2150 treatment. The RF2150 treatment improved soil moisture and significantly increased (18.9%) grain yield, (11.1%) biomass, (75.8%) WUEg, and (64.1%) WUEb of winter wheat and largely mitigated GWP and GHGI. The RF system with 150-mm deficit irrigation regime plays a significant role in increasing the biomass productivity and soil respiration rate and minimizing the seasonal greenhouse gas fluxes, GHGI, and field ET rates under 200-mm precipitation condition. Compared with TF practice, the plastic film mulching on ridges and furrow on the planting zone could significantly improve biomass and WUE and reduce N2O, CO2, and CH4 emissions. The RF2150 treatment should be very good water-saving approach and a powerful tool to decrease GHGI and GWP via increased biomass, WUE, soil respiration rate, and wheat yields under a dry-land farming system.

Increased photosynthesis and grain yields in maize grown with less irrigation water combined with density adjustment in semiarid regions.

In order to design a water-saving and high-yield maize planting model suitable for semiarid areas, we conducted trials by combining supplementary irrigation with different planting densities. Three planting densities (L: 52,500, M: 75,000, and H: 97,500 plants ha-1) and four supplementary irrigation modes (NI: no irrigation; IV: 375 m3 ha-1 during the 11-leaf stage; IS: 375 m3 ha-1 in the silking stage; and IVS: 375 m3 ha-1 during both stages) were tested. The irrigation treatments significantly increased the leaf relative water content, but the high planting density significantly decreased the relative water content during the silking and filling stages. After supplementary irrigation during the 11-leaf stage, IV and IVS significantly increased the photosynthetic capacity, but decreased the leaf water use efficiency. IS and IVS significantly increased the photosynthetic capacity after supplementary irrigation in the silking stage over two years. During the filling stage, IV, IS, and IVS increased the two-year average net photosynthetic rate by 17.0%, 27.2%, and 30.3%, respectively. The intercellular CO2 concentration increased as the density increased, whereas the stomatal conductance, transpiration rate, net photosynthetic rate, and leaf water use efficiency decreased, and the high planting density significantly reduced the leaf photosynthetic capacity. The highest grain yield was obtained using the IVS treatment under the medium planting density, but it did not differ significantly from that with the IS treatment. Furthermore, the IVS treatment used two times more water than the IS treatment. Thus, the medium planting density combined with supplementary irrigation during the silking stage was identified as a suitable water-saving planting model to improve the photosynthetic capacity and grain yield, and to cope with drought and water shortages in semiarid regions.

Effects of Gibberellin (GA4+7) in Grain Filling, Hormonal Behavior, and Antioxidants in High-Density Maize (Zea mays L.).

Dense plant cultivation is an efficient approach to improve maize production by maximizing the utilization of energy and nutrients. However, dense plant populations may aggravate the abortion rate of young grains, resulting in fewer kernels per ear. The rate and duration of grain-filling play decisive roles in maize grain yield. Therefore, to increase plant density, enhancing the grain-filling rate, extending the growth period of individual maize plants and regulating crop senescence would be the first priority. In this study, we examined the regulatory effects of GA4+7 under two application methods: shanks and silks were moistened by cotton full with GA4+7 solution at concentrations of 0, 10, 60, and 120 mg L-1. The results showed that GA4+7 improved the grain-filling rate by increasing the content of auxin, gibberellin, zeatin, and abscisic acid in grains compared to control plants. In addition, the auxin, gibberellin, and zeatin contents in the grains were positively and significantly correlated with the maximum grain weight and the maximum and mean grain-filling rates. Moreover, GA4+7 increased the activities of superoxide dismutases, catalases, and peroxidases and reduced the malondialdehyde content in leaves compared with untreated plants. At the concentration of 60 mg L-1, GA4+7 showed the greatest effect on shank and silk applications (Sh-60 and Si-60) followed by 10 mg L-1 (Sh-10) for shank treatment and 120 mg L-1 (Si-120) for silk treatment. Our results suggest that a concentration of 60 mg L-1 GA4+7 for shank and silk application may be efficiently used for changing the level of hormones in grains and antioxidant enzymes in ear leaves, which may be useful for enhancing grain-filling rate and delaying leaf senescence, resulting in an increase in maize grain yield.

Ridge-furrow mulching system and supplementary irrigation can reduce the greenhouse gas emission intensity.

In this study, in order to explore the greenhouse gas emissions and global warming potential (GWP) in winter wheat fields under the ridge-furrow mulching system (RF) with supplementary irrigation, three rainfall conditions (heavy rainfall = 275 mm, normal rainfall = 200 mm, and light rainfall = 125 mm) and four irrigation treatments (150, 75, 37.5, and 0 mm) were simulated during the growth period. Traditional flat planting (TF) was used as the control and we determined the emissions of N2O, CO2, and CH4, as well as the GWP and greenhouse gas emission intensity (GHGI). The results obtained after three years (October 2016 to June 2019) showed that when the amount of irrigation was the same during the winter wheat growth period, the N2O emission flux, CO2 emission flux, and GHGI under RF decreased by 3.30-23.78%, 5.93-6.45%, and 5.01-23.72% with rainfall at 275 mm, respectively, compared with those under TF. Under the same level of supplementary irrigation, the N2O emission flux, CO2 emission flux, and GHGI decreased by 0.8-4.18%, 5.05-13.53%, and 7.83-13.72%, respectively, with rainfall at 200 mm, and they decreased by 17.49-32.46%, 25.57-35.35%, and 6.22-30.20% with rainfall at 125 mm. Under the three rainfall conditions, the absorption of CH4 in the winter wheat field increased as the supplementary irrigation decreased. Our results showed that the RF system can satisfy the goal of achieving high yields and saving water, as well as reducing the GHGI to contribute less to global climate warming as an environmentally friendly irrigation method.

Cultivation modes and deficit irrigation strategies to improve 13C carbon isotope, photosynthesis, and winter wheat productivity in semi-arid regions.

Determining the effect of ridge-furrow cultivation mode on 13C carbon isotope discrimination, photosynthetic capacity, and leaf gas exchange characteristics of winter wheat leaves will help to increase wheat production. To verify these effects of cultivation modes with deficit irrigation will provide scientific basis for determining water-saving strategy. Therefore, a mobile rainproof shelter was used to explore the potential benefit of two cultivation modes: (1) the ridge-furrow (RF) precipitation system and (2) traditional flat planting (TF) with two deficit irrigation levels (150, 75 mm) and three precipitation levels (275 mm, 200 mm, 125 mm) were tested in this study. Plastic film mulching on ridges had significant effects on rainwater collection and improved soil water retention. Analysis of the light-response curve showed that RF2150 treatment significantly increased flag leaf net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), leaf WUE, and total contents of chlorophyll ab of wheat at flowering stage than that of TF planting. The RF system significantly increases maximum net photosynthetic rate (Pnmax) (16.2%), light saturation points (LSP) (6.7%), and Pn under CO2-response curves compared to the TF cultivation across the two irrigation and three simulated rainfall levels. The RF system significantly increased Δ13C (0.7%) and caused a notable increase in the intercellular to ambient CO2 concentration ratio (7.6%), dry matter translocation (54.9%), and grain yield plant-1 (19%) compared to the TF planting. Furthermore, Δ13C was significantly positively correlated with Pn, Gs, Ci/Ca, Ci, Tr, Pnmax, LSP, and grain yield. This study suggested that the RF2150 treatment was the best water-saving technique because it increased soil water content, Δ13C, biomass, grain yield, and leaf WUE.

Ridge-furrow mulched with plastic film improves the anti-oxidative defence system and photosynthesis in leaves of winter wheat under deficit irrigation.

In semi-arid areas of China, the ridge-furrow mulched with plastic film (RF) cultivation system is a common water-saving agricultural technique where the shortage of water resources has become a serious problem. Therefore, we aimed to explore whether this cultivation is actually an improvement over the traditional flat planting (TF) method while testing two deficit irrigation (150, 75 mm) levels to grow winter wheat. Furthermore, we examined the responses of the anti-oxidative defence system and photosynthetic capacity of winter wheat flag leaves under three simulated rainfall (275, 200 and 125 mm) conditions. The results showed that the RF system with 150 mm deficit irrigation and 200 mm simulated rainfall condition (RF2150) treatment raised soil water content (%) at the jointing and flowering stages and achieved higher net photosynthesis rates (Pn) in flag leaves. Furthermore, such improvements were due to the reduction of malondialdehyde (MDA) content and oxidative damage during different growth stages of winter wheat. The RF2150 treatment significantly increased the activities of superoxide dismutase (SOD); peroxidise (POD), catalase (CAT) and ascorbate peroxidase (APX) and the content of soluble protein (SP) during different growth stages of winter wheat. Furthermore, RF2150 treatment attained the highest value at the flowering stage, while also exhibiting significant declines in contents of proline, MDA, H2O2 and O2 in flag leaves. The higher free H2O2 and O2 scavenging capacity and better anti-oxidative enzyme activities under the RF2150 treatment were due to the lower level of lipid peroxidation, which effectively protected the photosynthetic machinery. The net photosynthetic rate of flag leaves was positively correlated with SOD, POD, CAT, APX and SP activities, and negatively correlated with proline, MDA, H2O2 and O2 contents. We concluded that the RF2150 treatment was the better water-saving management strategy because it significantly delayed flag leaf senescence and caused the increases in SWC, WUE, Pn, antioxidant enzyme activities and grain yield of winter wheat grown in semi-arid regions of China.

Deficit irrigation and fertilization strategies to improve soil quality and alfalfa yield in arid and semi-arid areas of northern China.

BACKGROUND: In the arid and semi-arid areas of northern China, overexploitation of fertilizers and extensive irrigation with brackish groundwater have led to soil degradation and large areas of farmland have been abandoned. In order to improve the soil quality of abandoned farmland and make reasonable use of brackish groundwater, we conducted field trials in 2013 and 2014. METHODS: In our study, we used three fertilization modes (CF, chemical fertilizer; OM, organic manure and chemical fertilizer; NF, no fertilizer) and three deficit irrigation levels (I0: 0 mm; I75: 75 mm; I150: 150 mm). RESULTS: The results showed that the activities of soil urease, alkaline phosphatase, invertase, catalase, and dehydrogenase in the OM treatment were significantly improved compared with those in the CF and NF treatments under the three deficit irrigation levels. Compared with NF, the OM treatment significantly increased soil organic carbon (SOC), water-soluble carbon (WSC), total nitrogen, microbial biomass carbon and nitrogen (MBC and MBN), and soil respiration rate, and significantly decreased soil C:N and MBC:MBN ratios and the metabolic quotient, thus improving the soil quality of abandoned farmland. Furthermore, the OM treatment increased alfalfa plant height, leaf area index, leaf chlorophyll content, and biomass yield. Under the CF and OM fertilization modes, the activities of urease and catalase in I150 were significantly higher than those in I0, whereas irrigating without fertilizer did not significantly increase the activity of these two enzymes. Regardless of fertilization, alkaline phosphatase activity increased with an increase in irrigation amount, whereas invertase activity decreased. DISCUSSION: The results showed that deficit irrigation with brackish groundwater under the OM treatment can improve soil quality. Over the two years of the study, maximum SOC, total nitrogen, WSC, MBC, and MBN were observed under the OM-I150 treatment, and the alfalfa biomass yield of this treatment was also significantly higher than that of the OM-I0 treatment. Therefore, the OM-I150 treatment could be used as a suitable measure not only to improve the quality of abandoned farmland soil but also to increase the alfalfa biomass yield in arid and semi-arid areas of northern China.

Exogenous Hormonal Application Regulates the Occurrence of Wheat Tillers by Changing Endogenous Hormones.

Plant hormones play important roles in regulating the occurrence of crop tillers. However, little is known about the relationships and the underlying mechanisms between endogenous hormones and the occurrence of wheat tillers induced by exogenous hormones. In this study, two winter wheat cultivars, Xinong 979 and Xiaoyan 22, were used to investigate the effects of the exogenous application of indole-3-acetic acid (IAA) and zeatin (Z) on the occurrence of wheat tillers and investigate underlying mechanisms regulating the occurrence of tillers. The results showed that the application of IAA inhibited the occurrence of tillers, and external Z application promoted the occurrence rate of tillers under low nitrogen conditions. Further analysis of the results showed that exogenous IAA completely inhibited the growth of tiller buds, while exogenous Z significantly promoted the growth rate of tiller buds in low nitrogen conditions. Endogenous hormones exhibit important functions in regulating the growth of tiller buds, which contents were affected by exogenous hormones. Furthermore, according to the principal component analysis and correlation analysis, the growth of tiller buds was significantly positively correlated with the content of endogenous Z, whereas it was significantly negatively correlated with the ratios of endogenous IAA to endogenous Z (IAA:Z) and endogenous abscisic acid (ABA) to endogenous Z (ABA:Z). Moreover, no significant correlation was observed between the growth of the tiller buds and the endogenous IAA, endogenous gibberellins (GAs), and endogenous ABA content. These results suggested that Z played key roles in regulating the tiller occurrence, and exogenous hormones regulated the growth of wheat tiller buds via affecting the Z contents, thus regulating the occurrence of wheat tiller.

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.

Deficit irrigation and planting patterns strategies to improve maize yield and water productivity at different plant densities in semi-arid regions.

Field research was done in two consecutive years to optimize deficit irrigation under different crop densities (low, medium, and high) using the ridge and furrow rainfall harvesting (RFRH) system. We demonstrate that applying deficit irrigation (375 m3 ha-1) at the flowering stage of maize grown at medium density (M: 75000 plant ha-1) under the RFRH system (MIF) can improve soil water storage (0-200 cm) at the bell, filling and flowering stages. MIF increased biomass by 10% and grain yield by 21%, thereby achieving a 17% increase in water use efficiency (WUE) and a 22% increase in precipitation use efficiency (PUE) compared with conventional flat planting (CKM). MIF also improved irrigation water use efficiency (IWUE) (9%) and irrigation water productivity (IWP) (46%) compared with no-irrigation under the RFRH system (MI0). We observed that applying deficit irrigation (750 m3 ha-1) at the bell and flowering stage (IBF) had positive effects on dry matter, leaf area, and evapotranspiration, but there were no significant increases in IWUE, IWP, WUE, biomass and grain yield compared with maize grown under IF at low, medium and high plant densities. The average net profit over the two years was 34% higher for MIF compared with the CKM treatment.

Planting Patterns and Deficit Irrigation Strategies to Improve Wheat Production and Water Use Efficiency under Simulated Rainfall Conditions.

The ridge furrow (RF) rainwater harvesting system is an efficient way to enhance rainwater accessibility for crops and increase winter wheat productivity in semi-arid regions. However, the RF system has not been promoted widely in the semi-arid regions, which primarily exist in remote hilly areas. To exploit its efficiency on a large-scale, the RF system needs to be tested at different amounts of simulated precipitation combined with deficit irrigation. Therefore, in during the 2015-16 and 2016-17 winter wheat growing seasons, we examined the effects of two planting patterns: (1) the RF system and (2) traditional flat planting (TF) with three deficit irrigation levels (150, 75, 0 mm) under three simulated rainfall intensity (1: 275, 2: 200, 3: 125 mm), and determined soil water storage profile, evapotranspiration rate, grain filling rate, biomass, grain yield, and net economic return. Over the two study years, the RF treatment with 200 mm simulated rainfall and 150 mm deficit irrigation (RF2150) significantly (P < 0.05) increased soil water storage in the depth of (200 cm); reduced ET at the field scale by 33%; increased total dry matter accumulation per plant; increased the grain-filling rate; and improved biomass (11%) and grain (19%) yields. The RF2150 treatment thus achieved a higher WUE (76%) and RIWP (21%) compared to TF. Grain-filling rates, grain weight of superior and inferior grains, and net economic profit of winter wheat responded positively to simulated rainfall and deficit irrigation under both planting patterns. The 200 mm simulated rainfall amount was more economical than other precipitation amounts, and led to slight increases in soil water storage, total dry matter per plant, and grain yield; there were no significant differences when the simulated rainfall was increased beyond 200 mm. The highest (12,593 Yuan ha-1) net income profit was attained using the RF system at 200 mm rainfall and 150 mm deficit irrigation, which also led to significantly higher grain yield, WUE, and RIWP than all other treatments. Thus, we recommend the RF2150 treatment for higher productivity, income profit, and improve WUE in the dry-land farming system of China.

Strategies for reducing the fertilizer application rate in the ridge and furrow rainfall harvesting system in semiarid regions.

The ridge and furrow rainwater harvesting (RFRH) system is a promising water-saving planting technique for dryland farming, but we lack a full understanding of the effects of different fertilizer rates (N:P) on plant nutrient uptake and nutrient use efficiency (NuUE) in foxtail millet using this planting method, as well as the available nutrient residues in the soil. We conducted field studies (Loess Plateau, China) comparing RFRH planting (R) and traditional flat planting (T) at four different fertilizer rates to determine suitable fertilizer application rates for R during 2013-2015. Compared with T, R improved the soil moisture and the utilization of rainwater and fertilizer, thereby enhancing the grain yield, water use efficiency (WUE), grain nutrient uptake, and NUE in a dry year, but with no improvements in a rainy year. The grain yield and WUE exhibited parabolic increasing trends as the fertilizer application rate increased over three years, but no significant increase was found when the fertilizer rate exceeded 189:96 kg N:P ha-1 under R, which significantly reduced the NuUE and might waste nutrients. Therefore, we recommend R combined with 189:96 kg N:P ha-1 as a promising planting strategy for foxtail millet in semiarid areas.