Effect of irrigation and nitrogen fertilization on the production of biogas from maize and sorghum in a water limited environment

The expansion of biogas production from anaerobic digestion in the Po Valley (Northern Italy) has stimulated the cultivation of dedicated biomass crops, and maize in particular. A mid-term experiment was carried out from 2006 to 2010 on a silt loamy soil in Northern Italy to compare water use and energy efficiency of maize and sorghum cultivation under rain fed and well-watered treatments and at two rates of nitrogen fertilization. The present work hypothesis were: (i) biomass sorghum, for its efficient use of water and nitrogen, could be a valuable alternative to maize for biogas production; (ii) reduction of irrigation level and (iii) application of low nitrogen fertilizer rate increase the efficiency of bioenergy production. Water treatments, a rain fed control (I0) and two irrigation levels (I1 and I2; only one in 2006 and 2009), were compared in a split–split plot design with four replicates. Two fertilizer rates were also tested: low (N1, 60 kg ha⁻¹ of nitrogen; 0 kg ha⁻¹ of nitrogen in 2010) and high (N2, 120 kg ha⁻¹ of nitrogen; 100 kg ha⁻¹ of nitrogen in 2010). Across treatments, sorghum produced more aboveground biomass than maize, respectively 21.6 Mg ha⁻¹ and 16.8 Mg ha⁻¹ (p < 0.01). In both species, biomass yield was lower in I0 than in I1 and I2 (p < 0.01), while I1 and I2 did differ significantly. Nitrogen level never affected biomass yield. Water use efficiency was generally higher in sorghum (52 kg ha⁻¹ mm⁻¹) than in maize (38 kg ha⁻¹ mm⁻¹); the significant interaction between crop and irrigation revealed that water use efficiency did not differ across water levels in sorghum, whereas it significantly increased from I0 and I1 to I2 in maize (p < 0.01). The potential methane production was similar in maize and sorghum, while it was significantly lower in I0 (16505 MJ ha⁻¹) than in I1 and I2 (21700 MJ ha⁻¹). The only significant effect of nitrogen fertilization was found in the calculation of energy efficiency (ratio of energy output and input) that was higher in N1 than in N2 (p < 0.01). These results support the hypothesis that (i) sorghum should be cultivated rather than maize to increase energy efficiency, (ii) irrigation level should replace up to 36% of ETr and (iii) nitrogen fertilizer rate should be minimized to maximize the efficiency in biomass production for anaerobic digestion in the Po Valley.     

Pig slurry fertilization in a double-annual cropping forage system under sub-humid Mediterranean conditions

In areas of Southern Europe with very intensive pig production, most of the pig slurry (PS) is applied as fertilizer. However, in the European Union, no more than 170 kg N ha⁻¹ year⁻¹ can be applied in nitrate vulnerable zones (NVZs) from livestock manures. In this context, a six-year trial was conducted for a maize-triticale double-annual forage cropping rotation under rainfed conditions. Four different N rates were applied (0, 170, 250 and 330 kg N ha⁻¹ year⁻¹), to evaluate their effect on crop yield, N uptake, unrecovered N and soil nitrate content. The corresponding PS rates were defined as zero (PS 0), low (PSL) medium (PSM) and high (PSH). The annual average dry matter (DM) yields (maize + triticale) for the PS fertilization treatments PS0, PSL, PSM and PSH were 12.6, 17.7, 20.2 and 22.0 Mg DM ha⁻¹, respectively. Maize DM yield was influenced mainly by weather conditions, and triticale DM yield was clearly influenced by initial soil NO₃⁻-N and PS fertilization rates. Unrecovered N was affected by PS fertilization rate and initial soil NO₃⁻-N content. A residual effect of the PS when applied to maize had an important effect on soil NO₃⁻-N and subsequent triticale DM yield. Moreover, total annual average unrecovered N, considering the sum of both crops (maize + triticale), were 91, 144, and 222 kg N ha⁻¹ in PSL, PSM and PSH, respectively. In order to avoid part of this unrecovered N, mainly by lixiviation of nitrates, PS fertilization in triticale should be applied as side dressing at tillering. The application of N, in the form of PS, at rates higher than the legally permitted maximum of 170 kg N ha⁻¹ year⁻¹, may result in better yields. However, high rates of PS fertilization may originate in significantly lower N use efficiency and a higher potential environmental impact in double-cropping systems, practiced in rainfed sub-humid Mediterranean conditions.     

Effects of reduced nitrogen input on productivity and N2O emissions in a sugarcane/soybean intercropping system

A seven-year (2009–2015) continuous field experiment was established at the South China Agricultural University in order to identify the effects of sugarcane/soybean intercropping and reduced N rate on ecosystem productivity, yield stability, soil fertility, and N₂O emissions. The randomized block experiment was designed with four cropping patterns (sugarcane monocropping (MS), soybean monocropping (MB), sugarcane/soybean (1:1) intercropping (SB1), and sugarcane/soybean (1:2) intercropping (SB2)) and two rates of N fertilization (300 kg hm⁻² (N1, reduced rate) and 525 kg hm⁻² (N2, conventional rate)). The results showed that the land equivalent ratio (LER) of all intercropping systems was greater than 1 (between 1.10 and 1.84), and the SB2-N1 optimally improved the land utilization rate among all treatments. The cropping patterns and N applied rates had no significant effect on sugarcane yield. The soybean yield was influenced by different cropping patterns because of different planting densities (4, 8 and 16 rows of soybean were plant under SB1, SB2, and MB, respectively) and was adopted in this experiment. In addition, under the SB2 cropping pattern, the soybean yield at the reduced N application rate was higher than that at the conventional N application rate. Wricke’s ecovalence (W_i²), the sustainable yield index (SYI) and the coefficient of variation (CV) were used to evaluate yield stability. Different treatments had no significant effects on sugarcane yield stability, as demonstrated by three indicators (W_i², SYI and CV), which indicated that intercropping with soybean and reduced N rate had no effect on sugarcane yield. For soybeans, the value of W_i² demonstrated that the stability of the intercropping system was higher than its counterpart monocropping system, as SYI and CV values indicated that SB2 had higher stability than SB1. During seven years of experiments, there was no significant difference in the soil fertility between MS and SB patterns. The soybean monocropping had a higher available K, pH and lower available P content than sugarcane inter- and mono-cropping. Different cropping patterns had a slight impact on N₂O emissions and the greenhouse gas intensity (GHGI) value. Higher N input promoted N₂O emissions and increased GHGI values. In conclusion, the present study observed that a 40% reduced nitrogen input combined with intercropping soybeans could maintain sugarcane yield and soil sustainable utilization, and that higher N fertilizer additions induced negative impacts on greenhouse gases emissions. Sugarcane intercropping with soybeans can reduce chemical fertilizer input and simultaneously maintain crop productivity; thus, it can be considered to be a reasonable practice for field management.     

干旱地区农田生态系统土壤温室气体排放机制

CO2、CH4和N2O是目前几种最主要的温室气体,在对全球气候变暖贡献中,农业作为重要的温室气体排放源对其有不可低估的作用。一般而言,旱地农田生态系统是大气CO2和N2O的排放源,黄土高原等旱地是CH4的吸收汇。CO2排放主要包括植物呼吸作用和土壤呼吸作用;CH4排放包括有机物的还原和氧化吸收两个过程;N2O排放包括硝化作用和反硝化作用两个过程。土壤微生物、土壤水分、土壤温度、土壤质地、施肥等均从不同角度影响着温室气体的释放与吸收。近些年,免耕、秸秆还田、地膜等保护性耕作技术在干旱地区农田生态系统中得到广泛应用。其中免耕可以减少CO2和N2O的排放量,增加土壤对CH4的吸收量;秸秆还田和覆膜对N2O排放的影响结果尚未统一,但秸秆还田促进CO2排 放抑制CH4吸收,而覆膜促进CH4吸收抑制CO2排放。加强且更深入更全面的研究旱地农田生态系统温室气体排放应该作为今后重点研究领域,为全球气候变暖提供更为准确的理论基础。     

Long-term effects of N fertilization on cropping and growth of olive trees and on N accumulation in soil profile

Two experiments were conducted for 13 years in two olive groves of southern Spain to study the long-term effect of nitrogen (N) fertilization on trees and soil. In the first experiment, 12-year-old ‘Picual’ olive trees were arranged in a split plot design with method of N application (soil versus a 50% soil:50% foliar combination) as the whole plot factor, and amount of N applied annually (0, 0.12, 0.25, 0.5 or 1.0 kg N tree⁻¹) as the subplot factor. In the second experiment, N application to 50-year-old ‘Picual’ trees was based on the previous season's leaf N concentration. Urea was the source of N in both experiments. During the last 4 years, soil samples were taken at 0–20, 20–40, 40–60, 60–80, and 80–100 cm depth to evaluate the effect of N application on soil eutrophication. Fertilization with N had no significant effects on yield, fruit characteristics, and growth of olive trees for the 13 years of study, even when leaf N concentration increased with the amount of fertilizer N applied. Combining soil and foliar application may reduce the amount of fertilizer N necessary to correct a possible N deficiency because our experiments showed this practice to be more effective in increasing leaf N that applying N only to the soil. Our results question the established deficiency threshold of 1.4% of N in dried leaf because no reduction in yield or growth was observed for lower concentrations. However, leaf N concentration did not drop below 1.2% after 13 years with no N application, probably because of N inputs from rainfall and the mineralization of organic N. Whereas under natural conditions of the non-fertilized treatments NH₄⁺–N represented the dominant fraction of mineral N in soil, accumulation of high amounts of NO₃⁻–N in the soil profile occurred in the fertilized plots, which represents a high risk of N leaching from soil. All these results suggest that annual applications of fertilizer N are unnecessary to maintain high productivity and growth in olive. Applying N only when the previous season's leaf analysis indicates that leaf N concentration is below the deficiency threshold, is thus a recommended practice to optimize N fertilization in olive orchards and to reduce N losses by leaching.     

The relevance of N fertilization for the amount of total greenhouse gas emissions in sugar beet cultivation

The agricultural sector is highly affected by climate change and it is a source of greenhouse gases. Therefore it is in charge to reduce emissions. For a development of reduction strategies, origins of emissions have to be known. On the example of sugar beet, this study identifies the main sources and gives an overview of the variety of production systems. With data from farm surveys, calculations of greenhouse gas (GHG) emissions in sugar beet cultivation in Germany are presented. Emissions due to the production and use of fertilizers and pesticides, emissions due to tillage as well as field emissions were taken into account. All emissions related to the growing of catch crops during fall before the cultivation of sugar beet were also included. The emissions are related to the yield to express intensity.The median of total GHG emissions of sugar beet cultivation in Germany for the years 2010–2012 amounted to 2626 equivalents of CO₂ (CO₂eq) kg ha⁻¹ year⁻¹ when applying mineral plus organic fertilizer and to 1782 kg ha⁻¹ when only organic fertilizer was applied. The CO₂eq emissions resulting from N fertilization exclusively were 2.5 times higher than those caused by diesel and further production factors. The absence of emissions for the production of organic fertilizers led to 12% less total CO₂eq emissions compared to the use of mineral fertilizer only. But by applying organic fertilizer only, there were more emissions via the use of diesel due to larger volumes transported (126 l diesel ha⁻¹ vs. 116 l ha⁻¹ by applying mineral fertilizer exclusively).As there exists no official agreement about calculating CO₂eq emissions in crop production yet, the authors conclude that there is still need for further research and development with the aim to improve crop cultivation and crop rotations concerning GHG emissions and the therewith related intensity.     

秸秆全量还田下晚稻季翻耕对双季稻田温室气体排放和产量的影响

翻耕有利于秸秆还田,为了探究秸秆全量还田下不同耕作措施对双季稻产量和温室气化排放的影响,在晚稻季设置浅旋耕和翻耕2个处理,采用静态暗箱–气相色谱法连续监测当季晚稻和第2年早稻季稻田温室气体排放,以阐明秸秆全量还田下晚稻季翻耕对稻田甲烷（CH₄）和氧化亚氮（N₂O）排放及产量的影响。与浅旋耕处理相比,晚稻季翻耕显著降低了当季晚稻CH₄累积排放量（19.04%）、综合温室效应（19.19%）和温室气体排放强度（22.02%）,而对N₂O累积排放量无显著影响。晚稻季翻耕对第2年早稻季稻田温室气体排放无显著影响。可见,翻耕的减排效应只体现在当季。此外,浅旋耕和翻耕处理对当季晚稻和第2年早稻产量及其构成均无显著影响。短期来看,秸秆全量还田下晚稻季翻耕有利于协同实现双季稻稳产和稻田温室气体减排。     

Using a multicriteria assessment model to evaluate the sustainability of conservation agriculture at the cropping system level in France

Several international research and development organizations are promoting conservation agriculture in a wide range of contexts. Conservation agriculture is based on a combination of three main principles: (i) minimal or no mechanical soil disturbance; (ii) diversified crop rotations and (iii) permanent soil cover (consisting of a growing crop or a dead mulch of crop residues). However, in the face of the diversity of practices that can be associated with conservation agriculture, of goals assigned to agricultural systems, and pedoclimatic contexts, there is still no empirical evidence about the overall performance of conservation agriculture in France. Global assessments of conservation agriculture, with the full or partial application of its principles and in different contexts, are required to provide a more comprehensive picture of the performance of such systems. We tackled these objectives simultaneously, by evaluating 31 cropping systems with the MASC^® model (for Multicriteria Assessment of the Sustainability of Cropping Systems). These systems were selected to represent a wide diversity of practices, from ploughed conventional systems to crop sequences based on the full application of conservation agriculture principles. Positive interactions were observed between the key elements of conservation agriculture, resulting in better sustainability performances (particularly in terms of environmental criteria). Nevertheless, the systems most closely respecting the principles of conservation agriculture displayed several weaknesses, principally of a social or technical nature, in this study. Careful attention should be paid to attenuating these weaknesses. A more detailed analysis of the results also suggested that decreasing soil tillage tends to decrease the overall performance of the system unless associated with a diversification of the crop rotation.     

Impacts and adaptation of the cropping systems to climate change in the Northeast Farming Region of China

The Northeast Farming Region of China (NFR) is a very important crop growing area, comprising seven sub-regions: Xing’anling (XA), Sanjiang (SJ), Northwest Songliao (NSL), Central Songliao (CSL), Southwest Songliao (SSL), Changbaishan (CB) and Liaodong (LD), which has been severely affected by extreme climate events and climatic change. Therefore, a set of expert survey has been done to identify current and project future climate limitations to crop production and explore appropriate adaptation measures in NFR. Droughts have been the largest limitation for maize (Zea mays L.) in NSL and SSL, and for soybean (Glycine max L. Merr.) in SSL. Chilling damage has been the largest limitation for rice (Oryza sativa L.) production in XA, SJ and CB. Projected climate change is expected to be beneficial for expanding the crop growing season, and to provide more suitable conditions for sowing and harvest. Autumn frost will occur later in most parts of NFR, and chilling damage will also decrease, particularly for rice production in XA and SJ. Drought and heat stress are expected to become more severe for maize and soybean production in most parts of NFR. Also, plant diseases, pests and weeds are considered to become more severe for crop production under climate change. Adaptation measures that have already been implemented in recent decades to cope with current climatic limitations include changes in timing of cultivation, variety choice, soil tillage practices, crop protection, irrigation and use of plastic film for soil cover. With the projected climate change and increasing risk of climatic extremes, additional adaptation measures will become relevant for sustaining and improving productivity of crops in NFR to ensure food security in China.     

Growth dynamics of winter wheat in the field with daily fertilization and irrigation

In a field experiment with fertilized and irrigated winter wheat the above-ground crop was sampled once a week. Phenological development, plant density and canopy height were recorded and the green surface areas of leaves, stems and ears were measured. Soil mineral nitrogen was sampled and the field climate monitored. There were four treatments. The daily irrigated/fertilized (IF) and daily irrigated (I) treatments were both irrigated by a drip-tube system. Liquid fertilizer was applied to IF following a logistic function according to calculated plant uptake. A total of 200 kg N ha⁻¹ was applied. Treatment I, control (C) and drought (D) were all fertilized once in spring with 200 kg N ha⁻¹. In treatment D transparent screens were used to divert rainwater. Dry matter production ranged between 1400 in D and 2352 g m⁻² in IF. The corresponding amount of nitrogen uptake ranged between 15.8 and 24.6 g m⁻². After harvest, soil mineral nitrogen was lowest in IF.
An increase in the availability of nitrogen and water enhanced total biomass production as well as grain yield and leaf area. The daily supply of nitrogen according to crop demand delayed nitrogen uptake and increased total uptake. The results suggest that when the nitrogen is supplied in accordance with crop demand, the efficiency with which the applied fertilizer is utilized increases and the risk for nitrogen leaching decreases.     

氮磷钾不同用量及配比对日光温室黄瓜产量和品质的影响

在日光温室内,采用无土栽培方式研究了不同氮磷钾用量和配比对黄瓜产量及品质的影响,结果表明：增加氮素的用量和比例可以显著提高黄瓜产量、单株果实数和单果重,适量增氮可显著提高果实可溶性蛋白含量,但进一步加大用量和比例则使之降低,增氮显著降低Vc含量,增加果实的硝酸盐含量,可溶性糖含量有升高趋势,但差异不显著;增磷对黄瓜产量、单株果实数和单果重亦有明显促进作用,对果实可溶性蛋白没有明显影响,大量增磷可以降低果实可溶性糖含量,增磷可明显降低Vc含量,但显著提高果实硝酸盐含量;同时增加氮磷提高黄瓜产量,但果实硝酸盐含量较对照增加95%。增钾没有明显的增产效果,对单株果实数和单果重影响不大,可以增加黄瓜果实的可溶性蛋白含量,显著降低Vc和可溶性糖含量,但相对于增氮、增磷,增钾使Vc下降的幅度较小,显著降低果实硝酸盐含量,且用量和比例越大,效果越明显。     

长期不同施肥对红壤微生物生长影响

研究长期不同施肥对农田生态系统土壤微生物的影响,为合理培肥提供理论支持。依托红壤旱地长期定位试验,取样分析土壤可培养细菌、真菌及防线菌含量。表明有机肥的长期施入增加了土壤可培养细菌、真菌和放线菌的数量。磷肥有助于土壤可培养细菌的生长,氮肥有助于真菌的生长,抑制好气性自生固氮菌的生长。土壤不平衡施肥对土壤微生物的生物量有很大的影响,对好气性纤维素分解菌的生长起抑制作用。施用有机肥有助于改善土壤微生物的生态结构,保持土壤微生物的生态环境,提高农田生态系统生产功能。     

Contribution of green manure legumes to nitrogen dynamics in traditional winter wheat cropping system in the Loess Plateau of China

Excessive application of N fertilizer in pursuit of higher yields is common due to poor soil fertility and low crop productivity. However, this practice causes serious soil depletion and N loss in the traditional wheat cropping system in the Loess Plateau of China. Growing summer legumes as the green manure (GM) crop is a viable solution because of its unique ability to fix atmospheric N₂. Actually, little is known about the contribution of GM N to grain and N utilization in the subsequent crop. Therefore, we conducted a four-year field experiment with four winter wheat-based rotations (summer fallow-wheat, Huai bean–wheat, soybean–wheat, and mung bean–wheat) and four nitrogen fertilizer rates applied to wheat (0, 108, 135, and 162 kg N/ha) to investigate the fate of GM nitrogen via decomposition, utilization by wheat, and contribution to grain production and nitrogen economy through GM legumes. Here we showed that GM legumes accumulated 53–76 kg N/ha per year. After decomposing for approximately one year, more than 32 kg N/ha was released from GM legumes. The amount of nitrogen released via GM decomposition that was subsequently utilized by wheat was 7–27 kg N/ha. Incorporation of GM legumes effectively replaced 13–48% (average 31%) of the applied mineral nitrogen fertilizer. Additionally, the GM approach during the fallow period reduced the risk of nitrate-N leaching to depths of 0–100 cm and 100–200 cm by 4.8 and 19.6 kg N/ha, respectively. The soil nitrogen pool was effectively improved by incorporation of GM legumes at the times of wheat sowing. Cultivation of leguminous GM during summer is a better option than bare fallow to maintain the soil nitrogen pool, and decrease the rates required for N fertilization not only in the Loess Plateau of China but also in other similar dryland regions worldwide.     

不同水氮处理对豫麦49-198籽粒抗氧化物含量的影响

2012-2013年度, 在温县和郑州大田条件下, 研究不同水氮处理对冬小麦品种豫麦49-198籽粒总酚、类黄酮、类胡萝卜素含量及抗氧化活性的影响。结果表明, 在施纯氮0~300 kg hm^–2范围内, 所有观测指标均随施氮量的增加而增加, 以施氮300 kg hm^–2处理最高。随灌水次数(0~2次)的增加, 总酚、类黄酮含量和抗氧化活性呈先增加后降低趋势, 以灌拔节水处理最高;类胡萝卜素含量在不同试点间表现不一致。水氮耦合, 以灌拔节水+施氮240~300 kg hm^–2处理的抗氧化物含量及抗氧化活性较高, 而总酚、类黄酮及类胡萝卜素的积累量则以灌拔节和开花水+施氮240~300 kg hm^–2处理较高。相关分析表明, 籽粒总酚、类黄酮含量与抗氧化活性均呈显著正相关, 表明总酚、类黄酮含量增加可以提高小麦籽粒抗氧化活性;不同深度土层土壤水分含量及硝态氮含量与籽粒抗氧化物质含量的相关性存在差异, 总体而言, 氮含量有助于总酚及类胡萝卜素含量的积累, 而水分含量可能有助于类黄酮含量的提高。     

长期施肥对设施土壤磷素积累及释放的影响

研究了长期定位条件下不同施肥处理对保护地土壤磷素积累及释放的影响。结果表明,施磷肥的土壤其全磷、速效磷和有机磷的含量明显高于不施磷肥的土壤,且在同一条件下,施加有机肥能提高土壤中不同形态磷素的含量。四种处理土壤全磷含量的大小顺序为：AP>BP>A>B,速效磷和有机磷含量的大小顺序为：AP>A>BP>B。有机肥能明显促进土壤磷素的释放,四种处理土壤磷素累积释放量的大小顺序为：AP>BP>A>B。抛物线扩散公式能很好地拟和土壤磷素释放特征。     

有机培肥与轮耕方式对夏玉米田土壤碳氮和产量的影响

探明不同轮耕和有机培肥方式对夏玉米田土壤碳氮及其酶活性的影响,对提升农田土壤肥力及促进玉米高产具有重要意义。设秸秆(P)与牛粪(F)两种有机培肥方式和小麦季旋耕-玉米季深松(RS)、小麦季深松-玉米季免耕(SN)、小麦季翻耕-玉米季免耕(CN) 3种轮耕方式,共6个处理,于2015—2016和2016—2017玉米收获期采样测定,研究了不同有机培肥和轮耕方式对土壤碳氮及其酶活性和作物产量的影响。结果表明,轮耕方式、有机肥及其交互效应对土壤肥力有显著影响。在0～10 cm和10～20 cm土层,与轮耕方式CN相比, RS和SN能够显著提高土壤有机碳、全氮含量和脲酶、蔗糖酶活性。在轮耕方式RS中,与施用牛粪相比,秸秆还田显著提高了10～20 cm、20～30 cm和30～40 cm土层的有机碳含量,增加了10～20 cm土层的全氮含量和蔗糖酶活性。在轮耕方式SN中,与秸秆还田相比,施用牛粪显著提高了0～10 cm和10～20 cm土层的有机碳、全氮含量和蔗糖酶活性,增加了各土层脲酶活性。与秸秆还田+翻耕-免耕(PCN)相比,秸秆还田+旋耕-深松(PRS)和施用牛粪+深松-免耕(FSN)能显著提高土壤肥力。在0～10 cm和10～20 cm土层,各处理中以FSN增加土壤有机碳、全氮含量和蔗糖酶、脲酶活性最为明显。轮耕方式、有机肥及其交互效应对产量有显著影响。轮耕方式RS和SN的产量较CN分别显著提高了1.89%～10.49%、5.44%～11.99%。在轮耕方式RS中,产量表现为秸秆还田较施用牛粪显著提高了2.91%～3.11%;而在轮耕方式SN中,则表现为秸秆还田较施用牛粪显著降低了5.02%～9.07%。两年玉米产量均表现为FSNPRSFRSPSNFCNPCN。综上所述,在6种处理中,处理FSN在提高土壤肥力和产量方面最为显著,可以作为试验及周边地区适宜的轮耕培肥方式。     

长期施用不同剂量氮肥对高粱产量、氮素利用特性和土壤硝态氮含量的影响

To determine a suitable nitrogen fertilizer application rate, an experiment was conducted using Jinza 34, Liaoza 27, Jinsi 2, Jinnuo 3, and Fenjiuliang 1 with six nitrogen (N) fertilization levels, including 0 (N0), 75 (N75), 150 (N150), 225 (N225), 300 (N300), and 450 kg hm^-2 (N450). The effects of long-term nitrogen fertilization with different levels on sorghum grain yield, nitrogen use characteristics and soil nitrate nitrogen distribution were investigated. The grain yield, grain number and N accumulation of sorghum increased initially and then tended to be stabile with the increase of nitrogen fertilizer application. Among them, the maximum increase of sorghum under N75 treatment compared with that under N0 treatment was 23.68%, 48.05%, and 51.86%, respectively. With the increase of nitrogen fertilizer application, the grain starch content decreased, while the grain starch yield increased firstly and then decreased. Nitrogen apparent recovery rate, nitrogen fertilizer agronomic efficiency and nitrogen use efficiency which were accumulated for five years were reduced significantly with the increase of nitrogen fertilizer application. Compared with the N150 treatment, nitrogen use efficiency accumulated for five years under N75 treatment, which was 63.01%, was increased by 76.91%. When nitrogen fertilizer application was beyond 225 kg hm^-2, after four to five years later, nitrate nitrogen residue was increased rapidly in the 60-200 cm soil layer year by year, NO₃^--N accumulation peaks distributed in the 0-200 cm soil layer and the risk of nitrate nitrogen leaching was increased. In view of the yield, starch yield, nitrogen utilization and environmental benefit, the reasonable nitrogen fertilizer application for sorghum was between 75 kg hm^-2 and 150 kg hm^-2.     

长期施用不同剂量氮肥对高粱产量、氮素利用特性和土壤硝态氮含量的影响

本研究于2015—2019年以晋杂34、辽杂27、晋饲2号、晋糯3号和汾酒粱1号为研究对象,设0(N0)、75(N75)、150(N150)、225(N225)、300(N300)、450 kg hm^-2(N450)6个氮素水平,调查其对产量性状、淀粉含量和土壤硝态氮以及氮素利用特性指标的影响,以探讨高粱合理的氮素施用方案。结果表明,高粱的产量、穗粒数及植株地上部氮素累积量,随施氮水平的增加呈先增加后趋于稳定的趋势,其中以N75处理增幅最大,较N0处理最大增幅分别可达23.68%、48.05%和51.86%;籽粒淀粉含量、5年叠加氮肥利用率、5年叠加氮肥农学效率和氮素5年叠加表观回收率随施氮水平的增加都存在不同程度的降低,其中N75处理下5年叠加氮肥利用率为63.01%,较N150处理提高了76.91%;籽粒淀粉产量则随施氮水平的增加呈先增加后降低的趋势。连续施氮4~5年后,施氮量≥225 kg hm^-2,残留的硝态氮在60~200 cm土层逐年累积,且在0~200 cm土层存在明显的累积峰,硝态氮淋失风险加剧。施氮量75~150 kg hm^-2之间,在满足高粱植株基本生长需求的同时,可以弥补了土壤氮库的消耗,有效降低了土壤硝态氮的淋失,亦有利于高粱产量和籽粒淀粉产量的形成。     

北疆膜下滴灌高产棉花灌溉和施肥模式的初探

摘 要：通过不同年际间,北疆膜下滴灌高产示范田中灌水、施肥措施对棉花产量及产量构成特点影响的研究。结果表明,新疆滴灌棉田产量逐步提高与棉花种植密度的增加,水肥后移,增加花期以后钾的施用量等栽培措施密切相关。在蕾期-盛花结铃期增加灌水次数,减少灌水周期、时间及灌水量;结铃期到始吐期,在保证灌水次数的同时,适当减少灌水量,能明显提高全生育期的水分利用效率,有效的节约生产成本。     

有机肥配施氮肥对滴灌春玉米产量及土壤肥力状况的影响

针对宁夏扬黄灌区沙质土壤肥力贫瘠、养分利用率低以及农田生产力弱等问题。通过两年连续田间定位试验,采用裂区试验设计,主处理为不施有机肥(+M)处理和施有机肥3000kghm^-2(+M)处理,副处理为施纯氮0(N0)、75(N75)、150(N125)、225(N225)和300kghm^-2(N300)5个不同氮肥用量,进行滴灌条件下有机肥与氮肥配合施用对玉米产量及土壤肥力状况的研究,探讨施肥对土壤养分、玉米产量的影响,以选择最佳的肥料配比,从而达到玉米高产、优质和土壤培肥的目的。结果表明,有机肥配施氮肥能有效增加土壤有机质、全氮、全磷、速效钾和速效磷含量,促进春玉米干物质累积并提高产量,以有机肥配施纯氮300kghm^-2和225kghm^-2处理的培肥效果最佳。有机肥配施氮150、225和300kghm^-2处理间的玉米产量无显著差异,但较不施氮肥处理产量分别提高了74.21%、91.33%和81.23%,施有机肥处理较不施有机肥处理平均增产24.28%。在试验区的推荐施肥量为3000kghm^-2有机肥配施225~300kghm^-2氮肥。