Crop Growth Period Research Articles

Quantitative evaluation of soil water balance under a ridge-furrow rainwater harvesting system in Chinese rainfed agroecosystem.

The ridge-furrow rainwater harvesting system (RFRH) is an advanced farmland management technology that plays a vital role in making full use of rainwater resources. However, it is not clear that RFRH affects crop yield and water use efficiency (WUE) by regulating soil water storage (SWS). Therefore, the present study conducted a meta-analysis to make a large compilation of previous studies and indirectly quantify the impact of RFRH on crop yield and WUE by analysing the effect of RFRH on SWS. The results showed that RFRH improved crop yield and WUE by 26.71% and 25.86%, respectively, by increasing SWS by 3.93% compared to the traditional flat cultivation. RFRH had a significant effect on increasing crop yield and WUE and improving SWS. A low ridge-furrow ratio and ridge-furrow mulching were recommended to obtain positive effects on crop yield and WUE when potatoes are grown in areas with high precipitation (600-800 mm). Furthermore, when nitrogen fertilization is applied during the crop growth period, we also found that a medium nitrogen fertilizer rate is recommended to achieve a significant positive effect on crop yield and WUE. Importantly, a win-win analysis showed the proportions of various groups in the target zone (zone I) to determine the appropriate strategy for RFRH of crops. The present study provides a scientific reference for the future application of the RFRH. The study provides scientific recommendations on crop types, ridge-furrow configurations, plastic mulching patterns and nitrogen fertilizer rate for future RFRH applications. © 2024 Society of Chemical Industry.

Biomonitoring of biocontrol across the full annual cycle in temperate climates: Post‐harvest, winter and early‐season interaction data and methodological considerations for its collection

Abstract Conservation biocontrol, the regulation of crop pests by naturally occurring biocontrol agents (e.g., predators and parasitoids), is predominantly monitored throughout periods of primary crop growth when pests exert the most observable impact on yields. Pest‐focused agricultural biomonitoring often overlooks post‐harvest, winter and even early‐season biocontrol, despite the significant predator–pest interactions during these periods that profoundly affect pest abundance and, consequently, crop yields. Rapid advances in biomonitoring, particularly in the detection of predator–pest interactions that underpin biocontrol, provide an opportunity to reconsider how and when we monitor these interactions. Advances in agricultural biomonitoring must transcend methodological innovation and encompass conceptual changes in the monitoring of agricultural systems. Here, we assess existing evidence supporting the importance of periods beyond primary crop growth for biocontrol and how predator–pest interactions are likely to evolve during these periods, subsequently influencing pest population dynamics during the primary crop growth period. We advocate for a greater concerted effort to establish continuous monitoring of biocontrol interactions, particularly beyond primary crop growth periods in temperate climates. To facilitate this, we also summarise the methodological approaches that can make it possible and explore how extending sampling across the full annual cycle might impact the practicalities and outcomes of these approaches. Year‐round monitoring of biocontrol interactions, both in crops and adjacent semi‐natural habitats, will provide a previously intractable understanding of predator–pest dynamics, offering significant potential to enhance our ability to optimise and manipulate these systems. This would manifest in reduced crop yield losses, pest infestation rates and disease transmission, with concomitant long‐term financial, environmental and land‐use benefits.

Sustaining the Yield of Maize, Blackgram, Greengram, Groundnut, Cotton, Sugarcane, and Coconut through the Application of Nutrients and Plant Growth Regulator Mixture.

The foliar application of nutrients and plant growth regulators (PGRs) at critical crop growth periods can improve the yield of field crops. Hence, the present study was conducted to quantify the effects of the combined application of nutrients and PGRs (crop-specific formulation) on maize, blackgram, greengram, groundnut, cotton, sugarcane, and coconut yield. In all the crops except coconut, the treatments included (i) a foliar spray of crop-specific nutrients and PGR combinations and (ii) an unsprayed control. In coconut, the treatments included (i) the root feeding of coconut-specific nutrients and PGR combinations and (ii) an untreated control. Crop-specific nutrient and PGR formulations were sprayed, namely, Tamil Nadu Agricultural University (TNAU) maize maxim 1.5% at the tassel initiation and grain-filling stages of maize, TNAU pulse wonder 1.0% at the peak flowering stage of green gram and black gram, TNAU groundnut-rich 1.0% at the flowering and pod-filling stages of groundnut, TNAU cotton plus 1.25% at the flowering and boll development stages of cotton, and TNAU sugarcane booster 0.5% at 45 days after planting (DAP), 0.75% at 60 DAP, and 1.0% at 75 DAP of sugarcane. The results showed that the foliar application of TNAU maize maxim, TNAU pulse wonder, TNAU groundnut-rich, TNAU cotton plus and TNAU sugarcane booster and the root feeding of TNAU coconut tonic increased the yield of maize, pulses, groundnut, cotton, sugarcane, and coconut, resulting in higher economic returns.

Chemical weed control in wheat (Triticum aestivum) and its residual effects on greengram (Vigna radiata)

Chemical weed control in wheat (Triticum aestivum) and its residual effects on greengram (Vigna radiata)

The Construction of a Crop Flood Damage Assessment Index to Rapidly Assess the Extent of Postdisaster Impact

Floods are among the most serious natural disasters worldwide; they cause enormous crop losses every year and threaten world food security. Many studies have focused on flood impact assessments for administrative districts, but fewer have focused on postdisaster impact assessments for specific crops. Therefore, this study used remote sensing data, including the normalized difference vegetation index (NDVI), elevation data, slope data, and precipitation data, combined with crop growth period data to construct a crop flood damage assessment index (CFAI). First, the analytic hierarchy process (AHP) was used to assign weights to the impact parameters; then, the Weighted Composite Score Method was used to calculate the CFAI; and finally, the impact was classified as sub-slight, slight, moderate, sub-severe, or severe based on the magnitude of the CFAI. This method was used for the Missouri River floods of 2019 in the United States and the Henan flood of 2021 in China. Due to the lack of measured data, the disaster vegetation damage index (DVDI) was used to compare the results. Compared with the DVDI, the CFAI underestimated the evaluation results. The CFAI can respond well to the degree of crop impact after flooding, providing new ideas and reference standards for agriculture-related departments.

Variation and attribution of energy distribution for salinized sunflower farmland in arid area

Agricultural water resources consumption and soil salinity interact with the distribution of radiation energy in arid salinized farmland. Understanding the temporal changes in energy distribution is necessary to enhance water resource use efficiency. Based on two years of monitoring the energy fluxes in a salinized sunflower field, it was found that field energy fluxes were dependent on available energy, and the temporal dynamics of energy distribution was strongly influenced by crop growth. As expected, soil moisture and meteorological conditions were the main factors limiting latent heat (LE) fluxes in the relatively dry year, with leaf area index showing a more significant positive correlation with LE under abundant soil moisture. Furthermore, path analysis revealed that soil moisture affected energy distribution at budding and flowering stages through the negative regulation of soil surface heat fluxes and the positive regulation of LE. The accumulation of soil salt decreased LE (with Pearson correlation coefficient of −0.59 and a total effect of −0.55), and positive regulated sensible heat (with Pearson correlation coefficient of 0.27 and a total effect of 0.31). Additionally, approximately 40% of actual evapotranspiration was contributed by groundwater, potentially influencing energy fluxes. Moreover, a negative correlation was observed between surface albedo and salinity, which might be another pathway influencing energy distribution. Our findings are important to understand energy distribution and water consumption during the crop growth period in salinized field in arid area.

Evaluating the impacts of flooding on crop yields by different meteorological indices: A regional case study in the middle-lower reach of the Yangtze River, China

Flooding is a worldwide destructive disaster that severely restricts agricultural production. Meteorological indices are common tools for regionally assessing the impact of flooding on crop yields, but their performances are rarely compared. In this work, six convenient meteorological indices, namely, precipitation (P), standardized precipitation anomaly (PA), China Z index (CZI), standardized precipitation index (SPI), standardized precipitation and evapotranspiration index (SPEI), and standardized antecedent precipitation and evapotranspiration index (SAPEI), were employed to establish correlations between flooding intensity and crop meteorological yield (FL-Ym correlation). Four major crops in the middle-lower reach of the Yangtze River (cotton, oilseed rape, wheat, and maize) were selected as the study crops. The results indicated that the flooding intensities quantified by the SPI, SPEI, and CZI had strong interconnections, whereas those quantified by the P and SAPEI were less related to the others. In the cases with stronger negative FL-Ym correlations, different indices were more likely to yield consistent identifications. In terms of the districts witnessing significant FL-Ym correlations, in only 26%, 41%, 44%, and 75% of them (respectively corresponding to cotton, wheat, maize, and oilseed rape), the correlations were consistently identified as significant by the majority of the indices, demonstrating the nonnegligible influence of index selection. The relative performances of the examined indices varied with the employed calculation periods (whole growth period and single critical stage), whereas the SPEI was generally the best performer. The SAPEI performed best in assessing the flooding impact during crop critical growth stages, in sharp contrast with its mediocre performance over the whole crop growth period. According to the results of multiple indices, flooding during the middle stages of the study crops exerted the greatest negative impact. Additionally, oilseed rape and Anhui Province were identified as the crop and the region most affected by flooding. This work can provide support for flooding disaster assessment and agricultural water management.

Intercropping prairie cordgrass with kura clover had little effect on soil biogeochemistry

AbstractIntercropping kura clover (Trifolium ambiguum) (KC) with prairie cordgrass (Spartina pectinata) (PCG) has great potential for biofuel feedstock on marginal lands. This study evaluated the impacts of 10‐year PCG‐KC intercropping and PCG monoculture fertilized with different nitrogen (N) rates of granular urea (five treatments: PCG‐KC, PCG‐0N, PCG‐75N, PCG‐150N, and PCG‐225N) on soil biogeochemical properties: (i) in the surface soil (0‐ to 10‐cm depth) at three different sampling times during the crop growing season: spring (April, pre‐emergence), summer (June, active growth), and fall (November, post‐harvest); and (ii) at different soil depths (0–5, 5–15, 15–30, 30–45, and 45–60 cm) (only total carbon (C) and N) in fall 2021. All soil biogeochemical parameters were higher during summer as compared to spring and/or fall, except urease activity, ammonium‐N, microbial biomass C and N, and fluorescein diacetate (FDA). On average over the sampling times, PCG‐KC had significantly higher β‐glucosidase activity and hot‐water extractable organic N than PCG‐0N; but no significant difference between PCG‐KC and N‐fertilized PCG. Cold‐water extractable organic N was significantly lower than the highest N rate, but not significantly different from PCG‐0N and lower N rate treatments. Urease activity under PCG‐KC treatment was double that of PCG‐0N and PCG‐75N; FDA was higher in PCG‐KC than all monocultures. No treatment effect was found on soil total C and N, except that they decreased with depth. Overall, intercropping PCG‐KC showed some benefits in terms of promoting soil biogeochemical properties during crop growth periods, having lower residual reactive N in the soil, and maintaining biomass yield and quality on marginal lands.

Micro Irrigation in Rice: A Review

Rice (Oryza sativa) is the most important staple food crop over half of the world’s population and it provides 21 per cent of global human per capita energy. In India, rice is widely grown as the second food crop occupying about 43 million hectares of area. Water scarcity is a major constraint in the development of rice farming in some parts of the world. The water required to produce unit kg of rice is as high as 4000-5000 liters under conventional methods of water application (Transplanting under submerged conditions). During the crop growth period of rice, the amount of water usually applied to field is often much more than the actual field requirement because of adopting traditional flood irrigation methods. In order to meet the growing demand for water it is necessary to use water efficiently and reduce the loss of water. One such practice to conserve water is adoption of micro irrigation to a water loving crop like rice to reduce the wastage of water and to increase the water use efficiency. Micro irrigation is defined as the application of small quantities of water directly above and below the soil surface, usually as discrete drops, continuous drops or tiny streams through emitters placed along a water delivery line.

Weed management in isabgul (Plantago ovata Forsk)

A field experiment was conducted during 2013-14 to 2015-16 at SeedSpice Research Station, S.D. Agricultural University, Jagudan on“Integrated weed management in isabgol ( Plantago ovata Forsk )”. Thesoil was loamy sand in texture, neutral in soil reaction, with low in organiccarbon, medium in available phosphorus and potash. There were tentreatments consisting physical and chemical weed control as well as theirintegration. Weed control treatments affected considerably on growth andyield attributes of isabgol. Whereas, there was no positive impact on testweight. The maximum and minimum values of all the growth and yieldattributes were achieved under treatment when crop was facilitate with twointer-culturing fb hand weeding at 25 and 40 DAS and unweeded controltreatments, respectively. Similarly, Physical method of weed control i.e.Two inter-culturing fb hand weeding at 25 and 40 DAS recordedsignificantly higher seed yield over rest of the treatments. The weeds werecontrolled efficiently resulted in higher seed yield under physical method.Effective removal of weeds throughout the crop growth period better spaceand resources utilization i.e., moisture, nutrients, solar radiation etc. Theadoption of a purely physical method of weed control i.e. treatment T : two9inter-culturing fb hand weeding at 25 and 40 DAS recorded significantlylower sedges, monocot, dicot and total weed count and dry weight ofweeds during investigation. Thus, performing two inter-culturing followedby hand weedings at 20 and 40 DAS produced sustainable and qualityseed yield and maintained the soil health.

Evaluation of Germplasm for Reproductive Stage Salinity Tolerance in Rice (Oryza sativa L.)

The current study was carried out to identify salt tolerant genotypes by screening 76 rice germplasm at reproductive stage salinity stress. The test entries were subjected to salt stress under field conditions and salinity was noted at different intervals of crop growth period i.e., 30 and 67 days after sowing and at the time of harvesting with the pH value of 5.4 and electrical conductivity of 4.3 dSm-1, 5.3 dSm-1and 7.2 dSm-1 respectively. The characters namely, salinity score, days to 50 percent flowering, plant height, panicle length, productive tillers/plant, number of filled grains/panicle, total number of grains/panicle, spikelet fertility and grain yield/plant were studied under saline conditions. Variability, heritability and genetic advance as percent of mean showed high genotypic and phenotypic coefficient of variation for grain yield plant-1indicating the presence of considerable amount of variation among the genotypes for potential yield improvement through selection. The trait grain yield per plant had high heritability coupled with high genetic advance as percent of mean indicating that it is regulated by additive gene action and therefore selection could be practiced based on phenotypic performance. Association studies under saline conditions, revealed favorable and significant correlation of grain yield per plant with days to 50% flowering, panicle length, plant height, total number of grains per panicle, number of filled grains per panicle and productive tillers per plant whereas, spikelet fertility and plant height on the other hand, recorded negative non-significant correlation, indicating the undesirable causes of salinity on plant growth and yield potential.

Infrared thermometry-based stress indices as indicators of yield performance and seasonal evapotranspiration in potato plants grown under different moisture and potassium regimes

As the demand for food continues to rise and water availability challenges intensify, the delicate equilibrium between efficient water usage and sustainable agricultural production has become increasingly pivotal. Recognizing the significance of water stress monitoring and nutrient management in the country's agricultural landscape, two years of field trials (2018–2019 and 2019–2020) were conducted at the Regional Research Station, Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia, to demonstrate the efficiency of canopy temperature-based indices for monitoring crop water stress in potato (cv. Kufri Jyoti) under varied irrigation (IW:CPE = 0.4, 0.8, 1.2 and 1.6) and potassium doses (K2O @ 100, 150 and 200 kg ha−1). The seasonal evapotranspiration of potato plants ranged from 121.0 mm to 320.9 mm during the crop growth period, and it exhibited a quadratic relationship with both the total dry biomass and the tuber yield. In 2019–2020, the highest water use efficiency (WUE) of 12.74 kg m−3 was obtained from the application of IW; CPE= 1.20 with the application of K2O @ 200 kg ha−1. In the following year, the highest WUE of 9.78 kg m−3 was obtained from irrigation at IW:CPE= 1.60, along with K2O application @ 200 kg ha−1. During a major part of the growth period, the canopy air temperature difference (CATD) was greater in the treatments in which irrigation was applied at IW:CPE = 0.4 and 0.8 than in those in which irrigation was applied at higher levels, i.e., IW:CPE = 1.2 and 1.6, implying the effectiveness of CATD as a stress indicator. The stress indices, stress degree days (SDD) and crop water stress index (CWSI) accumulated over the crop growing season showed decreasing trends with increasing irrigation and potassium doses. Both the accumulated SDD and accumulated CWSI showed a strong inverse relationship with tuber yield. The significant linear relationship between tuber yield and the seasonal accumulation of both infrared thermometry-based stress indices (i.e., SDD and CWSI) may help to predict crop yield in response to seasonal moisture stress and thus aid in strategic crop planning under the limited availability of irrigation.

Coupled Calculation of Soil Moisture Content and PML Model Based on Data Assimilation in the Hetao Irrigation District

Most Penman-Monteith-Leuning (PML) evapotranspiration (ET) modeling studies are dominated by consideration of meteorological, energy, and land use information, etc., but the dynamic coupling of soil moisture content (SM), especially in terms of improving accuracy through assimilation, lacks sufficient attention. This paper proposes a research framework for the dynamic coupling simulation of PML model and SM based on data assimilation, i.e., the remote sensing monitored SM is combined with soil evaporation of PML to obtain high-precision time-continuous SM data through data assimilation; simultaneously, dynamical soil evaporation coefficients are generated based on the assimilated SM to improve the simulation accuracy of the PML model. The new scheme was validated at a typical irrigation zone in north China and showed obvious improvements in both SM and ET simulations. Moreover, the effect of the assimilation of SM on the simulation accuracy of ET for different crop growth periods is further analyzed. This research provides a new idea for the coupling simulation of the SM and PML models.

Impact of Weather Parameters on Seasonal Incidence of Oriental Armyworm, Mythimna separata (Lepidoptera; Noctuidae) Infesting Maize Ecosystem in North Kashmir

The investigation on the seasonal incidence of oriental armyworm, Mythimna separata was conducted at the Faculty of Agriculture, Wadura SKUAST-K during kharif 2021. Shalimar composite-6 maize variety was cultivated under the standard practices for Kashmir valley, recommended by SKUAST-K. The pest activity during the crop growth period was monitored by using light traps and visual observations. Findings revealed that adult M. separata on maize emerged in the 18th standard meteorological week (SMW) with its peak in the 24th week and remained active until the 37th week. Similarly, armyworm caterpillars appeared in the 19th to 37th SMW and reached their peak in the 29th week in the maize ecosystem during 2021. Moreover, the percentage of infestation during the Kharif season was found to be minimum of 10 per cent in the 19th SMW, reaching its peak of 63 per cent in the 29th SMW. The infestation gradually decreased and persisted for eight weeks, with 10 per cent infestation in the 37th SMW. The relationship between adult population and weather parameters showed a positive correlation with maximum temperature (r = 0.14) and a negative correlation with minimum temperature (r = -0.22), morning relative humidity (r = -0.52*) and evening relative humidity (r = -0.47*). However, M. separata adult populations showed a significant negative association with rainfall (r = -0.51*). Correlations drawn between important weather parameters and larvae of M. separata showed significant positive correlation with maximum temperature (r = 0.60**) and minimum temperature (r =0.56**), while morning RH (r = -0.36) and evening RH (r = -0.29) showed negative association and rainfall (r =-0.16) also exhibited negative association with the larval infestation of M. separata during Kharif 2021. The study on percentage infestation also demonstrated a significant positive correlation with maximum temperature (r = 0.47*) and minimum temperature (r = 0.53*), while morning relative humidity (r = -0.22) and evening relative humidity (r = -0.29) showed negative associations. Rainfall (r = -0.20) displayed a negative correlation with the per cent infestation of M. separata.

Enhancing Groundnut Productivity in Anantapur District, Andhra Pradesh: Identifying Constraints and Developing Adaptation Strategies

India is a world leader in groundnut farming. A purposive and random sampling technique was used for the study and conducted in KVK operated mandals of Anantapur and Satya Sai district. Ten mandals of KVK operational area were selected purposively where Cluster Front-Line Demonstrations were conducted and from each mandal 2 villages were selected purposively by KVK. Eight farmers from each village were selected randomly, thus making a total of 160 respondents for this study. An ex-post facto research design was used and the data were collected by interview method and enquired about the constraints faced by them for low groundnut productivity and queried suggestions to overcome the constraints faced by them. From the study, it was revealed that major constraints of the farmers faced were uncertainty in rainfall during crop growth period (96.25) followed by lack of irrigation facility (92.5 %), shortage of labour during critical stages (88.75%), low production due to pest and disease infestation (87.5%) and non-availability of appropriate market price (86.25) as reported by the farmers. Among the suggestions offered by farmers it was the supply of inputs at subsidized rate (76.25 %) ranked first followed by remunerative price should be made available to the groundnut farmers during drought years (75.0%) ranked second and irrigation facilities should be made available (72.5%) ranked third.

Evaluating thermotolerant sunflower genotypes with temperature induction response (TIR) technique

High temperature affects various physiological processes of the plant. Delayed sowing and changing climate both subject the crop to increasing temperatures during the crop growth period. There is a need to take on a technique to screen the wide number of genotypes for high-temperature tolerance. In the present study, a screening protocol was followed based on the principle of “acquired tolerance” in which 47 sunflower seedlings were exposed to sub-lethal heat stress to induce tolerance before subjecting to subsequent lethal stress and the second set were directly exposed to lethal stress. Significant variation was observed for the traits - survival percentage, total seedling length, and seedling weight. Tolerant inbreds were identified using Z distribution and PCA. Results suggested that TIR is a rapid and powerful technique that can be used to screen large number of germplasms to identify thermotolerant lines.

Trends and climate response in the yield of staple crops across Northeast China

Understanding how climate change has been affecting crop yield is a prerequisite to inform adaptation decisions and to ensure global food security. The Northeast China (NEC), located in high-latitude area, is significantly affected by climate change. There is a high demand for quantitative information on impacts of climate variability on crop yields in NEC. In this study, we applied panel regression models to explore the yield-climate relationship and its spatial variations based on experimentally observed yield (Ys) and the county-scale statistical yield (Yc) of three typical crops (e.g., maize, rice and soybean) across NEC from 1981 to 2010, as well as contemporary climate data. The results indicated that Ys (Yc) of maize, rice and soybean during the past three decades increased by 64.2% (82.0%), 47.5% (55.3%), and 59.2% (58.0%), respectively. Moreover, we found climate during crop growth period had changed significantly and the change had caused measurable impacts on crop yields. Changes in temperature, precipitation and solar radiation jointly decreased Ys (Yc) of maize and soybean by 1.3% (0.7%) and 0.3% (1.1%), respectively, however increased Ys (Yc) of rice by 1.2% (2.2%), with a large spatial difference. Therefore, the impact of climate change on yields of three crops was far less than the actual increase in crop yields. Our finding suggest that other factors, mainly improved management practices, may be the main reason for the significant increase in crop yields in NEC over the past few decades. Although historical climate change also played an important role in the yields of three crops, certain improvement in management measures not only compensated for the negative impact of climate change, but also greatly promoted the increase in crop yields. Therefore, in proposing strategies for crop production to cope with climate change, we need in-depth assessments of the role of improved management.

Nitrate leaching characteristics of red soils from different parent materials in subtropical China

Globally, nitrate (NO3−) leaching from agroecosystems has been of major concern. There is evidence that NO3− leaching exhibits intense seasonal variation in subtropical regions. However, influencing factors to the seasonal dynamics remain unclear. In this study, a two-year field lysimeters experiment was conducted with three red soils derived from different parent materials (Quaternary red clay (QR), red sandstone (RS), and basalt (BA)). An N fertilizer (15N-enriched urea, 10 atom% excess) of 200 kg N ha−1 yr−1 was applied for maize. The effect of parent material on NO3− leaching characteristics was examined in surface (0–20 cm) and subsoil (20–100 cm) layers. The results showed due to the weakening of abundant drainage, there was no significant effect of parent materials on NO3− leaching characteristics in surface layers. Environmental factors (precipitation and temperature) and fertilization together led to obvious seasonal characteristics, i.e. abundant NO3− leaching during both crop growth and fallow periods. In subsoil layers, NO3− leaching characteristics were completely different among three soils. The concentrations and δ15N of NO3− in QR and RS soils showed a continuous increase after first year's fertilization, while those in BA soil remained relatively stable after reaching peak levels around harvest in first year. Meanwhile, the NO3− leaching amount in BA soil was significantly lower than in the other two soils. These might be explained by different NO3− adsorption capacities caused by the differences in mineral composition and free iron and aluminium contents. These elucidated in subsoil layers, NO3− leaching characteristics highly depended on parent materials. Meanwhile, adsorption capacity was limited and cannot slow NO3− leaching in the long run. Our results suggest that seasonal variation of NO3− leaching in surface layers and temporary retardant effect from NO3− adsorption capacity in subsoil layers should receive much attention when calculating and predicting NO3− leaching in subtropical regions.

Crop Coefficient of Sunflowers under Drip Irrigation with Plastic Film in Different Hydrological Years in the Hetao Irrigation District

An accurate assessment of crop water requirements during the crop growth period can help organize irrigation schedules and investigate the hydrological environments in irrigation districts, especially in shallow groundwater districts. In irrigation scheduling, crop coefficients, representing three development stages, play a critical role in modeling evapotranspiration. Therefore, in this study, the crop coefficient (Kc) of sunflowers under drip irrigation in different hydrological years in the Hetao irrigation district with shallow groundwater is determined. Based on the analysis of rainfall frequency, the experimental situations of 2012, 2013, and 2014 are adopted as high, normal, and low flow years. Using the water balance method, groundwater recharge and crop evapotranspiration in different hydrological years were investigated. The results showed that the groundwater recharge in a high-flow year was larger than that in normal and low-flow years with values of 67.47, 66.75, and 42.61 mm, respectively. Crop evapotranspiration is directly related to the irrigation amount at the same growth stage. The Kc of sunflowers in a high-flow year is higher by 0.1 and 0.15 than that in normal and low-flow years. The Kc of sunflowers under drip irrigation is lower than that under surface irrigation by 8.9% in the initial and late stages of sunflower growth, but higher than that by 10.6% in the mid-stage, which is due to differences in small water potential differences and less evapotranspiration in the initial and late stages under drip irrigation. The study is of great significance for formulating a reasonable schedule of drip irrigation with shallow groundwater and improving the field environment.

Response of soil microbial properties in the life cycle of potatoes to organic substitution regimes in North China

Organic substitution regimes (OSR) can improve soil microbial properties in crop production. However, the dynamic responses of soil microbial flora and its driving factors in crop growth periods under OSR are still unclear. Here, a 2-year fertilizer field trial was conducted to explore the response of soil chemistry and microbial properties to OSR in the life cycle of potatoes (Solanum tuberosum L.) in North China. The fertilization treatment included only mineral fertilizer (ConN), substitution of 30% mineral N with organic N (M30), and substitution of 60% mineral N with organic N (M60); soil samples were collected and analyzed in the early flowering period (EP), flowering period (MP), and maturity period (LP) of potatoes. As the potato growth period progressed, M30 and M60 increased soil organic carbon (SOC) compared with ConN. Soil total nitrogen (pH) increased (decreased) under M60, while soil available potassium was similar across three treatments. Compared with ConN, soil bacterial Chao, Shannon, and PD indexes significantly increased under M30 and M60 in MP and LP, and the fungal Shannon index increased in LP. Soil bacterial and fungal community structures under M30 and M60 were only significantly separated from ConN in MP. The bacterial communities of dominant phyla or genera responded more sensitively to the fertilization regimes than the flora of fungi, and the changes in the flora mainly occur in EP and MP. Redundancy analysis revealed that SOC and available phosphorus were highly correlated with soil microbial community compositions. Compared with ConN, soil microbial network complexity and fungal network robustness were higher under M30 and M60, while bacterial network robustness showed the opposite trend. Partial least squares pathway modeling showed that the conversion in the fertilization system or growth period had a direct positive effect on the C/N-cycling function of soil bacteria, but not on the C-degradation function of fungi. Our research has important theoretical implications for the development of microbial fertilizers and fertilization management in different potato growth periods.