This study aimed to provide precise nitrogen (N), phosphorus (P), and potassium (K) fertilization guidance for potato production in the Western part of China’s Inner Mongolia, where imbalanced nutrient application limits yield and nutrient use efficiency. Using data from 109 field trials spanning 2002–2023 across 3 major potato-producing regions of Western Inner Mongolia, the QUEFTS model was applied to estimate nutrient requirements by analyzing yield response, agronomic efficiency, and intrinsic efficiency parameters. Average tuber and shoot yields were 26.5 and 5.7 t·ha−1 (harvest index 0.75), with total plant uptake of 137.7 kg N, 43.6 kg P, and 164.5 kg K per hectare. Intrinsic efficiency (IE) and its reciprocal, the requirement of internal efficiency (RIE), ranged from 106.3–1162.4 kg tuber kg−1 nutrient and 0.86–9.41 kg nutrient t−1 tuber for N, 199.0–2173.9 kg·kg−1 and 0.46–5.03 kg·t−1 for P, and 69.3–455.4 kg·kg−1 and 2.20–14.44 kg·t−1 for K. Yield response correlated negatively with relative yield (R2 = 0.347–0.437), while agronomic efficiency showed a quadratic relationship (R2 = 0.460–0.657). The 2.5th percentile IE values were identified as suitable model boundaries for maximum accumulation and dilution: 178–583 kg·kg−1 for N, 420–1589 kg·kg−1 for P, and 136–417 kg·kg−1 for K. A linear nutrient uptake-yield relationship was maintained until yields reached 60

Context: Potato yield and quality are largely determined by the balance between assimilate production (source) and storage (sink), yet the variation in source-sink dynamics across different varieties and the specific effects of mineral nutrients are not well understood. Methods: This study aimed to address these gaps through field experiments conducted in 2021 and 2022 with three potato varieties: "Lucinda" (fresh consumption), "Mailken1" (frying processing), and "Dongnong310" (starch processing). The varieties were subjected to five fertilizer treatments: farmers' practice (FP: 250-113-113 kg N-P2O5-K2O ha-1), Nutrient Expert (R)-based fertilizer recommendation (NE: 210-100-200 kg N-P2O5-K2O ha-1), and three nutrient omission treatments (NE-N, NE-P, and NE-K) based on the NE recommendation. Results: The results showed that Dongnong310 exhibited higher source supply, sink demand, and sink-source differences compared to Lucinda and Mailken1. Despite limited source supply, all varieties showed strong sink demand, suggesting that yield formation was primarily constrained by source availability. Compared to FP, the NE treatment resulted in increased tuber yield across all varieties. Partial least squares structural modeling (PLS-SM) revealed that excessive nitrogen input reduced starch content, high phosphorus inhibited the accumulation of reducing sugars, and increased potassium enhanced both reducing sugar and VC content. Conclusion: The nutrient management adjustments using Nutrient Expert (R) for different intended uses: increasing potassium for fresh consumption varieties, moderately raising phosphorus while reducing potassium for frying processing varieties, and reducing nitrogen for starch processing varieties. Implication or significance: These insights provide a framework for implementing nutrient management strategies tailored to optimize potato production for specific intended uses.

Context: Continuous cropping is widely practiced to maximize economic benefits and land utilization, but it often leads to outbreaks of soil-borne diseases, posing significant challenges to crop production and sustainable use of farmland soil. To sustain soil fertility and productivity in continuous cropping system, various fertilization strategies have been explored. However, the relationship between fertilization and soil microbial communities, particularly concerning soil-borne diseases, remains poorly understood. Objective: This study aims to investigate the mechanism of optimized fertilization in mitigating soil-borne diseases by comparing the responses of bulk and rhizosphere soils to different fertilizer applications. Methods: We investigated the effects of fertilization methods on soil chemical properties, microbial communities, early blight and yields through a six-year continuous potato cropping experiment, including optimized fertilization (NPK), farmer fertilization practice (FP), nutrient omissions, and application of agricultural organic materials. Results: NPK alleviated early blight in potatoes and slowed down yield reduction by 33.9 %. NPK with corn straw or sheep manure increased particulate organic matter (POM), reduced the disease index (2.25% and 3.80%, respectively), and had more significant effect on fungal community in bulk soil (R2 = 0.45, P = 0.002) than rhizosphere soil. The results demonstrated that optimized fertilization facilitated carbon accumulation in bulk soil and nitrogen fixation in rhizosphere soil. Moreover, the impacts of nitrogen, phosphorus, or potassium on microbial communities differed between bulk and rhizosphere soils, largely due to the responses of POM. We identified POM as a key factor influencing soil-borne diseases and demonstrated its relationship with disease suppression. Conclusions: Optimized fertilization was found to mitigate early blight and reduce yield loss by increasing POM, a key factor influencing soil-borne diseases and balancing fungal communities in continuous cropping soils. Significance: Our research sheds light on the mechanism of optimized fertilization in abating soil-borne diseases, which remained elusive in prior studies. For the first time, we identified and demonstrated the strong association between POM and soil-borne disease. These findings highlight the crucial, yet often overlooked, role of bulk soil quality in suppressing soil-borne disease and provide valuable insights into cultivating disease-suppressing soils.

The nutrient availability of carbon (C), nitrogen (N), and phosphorus (P) has been decreasing due to a decline in the biological function of yellow soil, limiting potato yield (PY). Increasing biochar or organic fertilizer input is an effective way to improve soil microbiological fertility. However, indexes to regulate soil microbiological fertility using biochar and organic fertilizer individually or in combination and these indexes’ associations with PY remain unclear. In this study, four fertilization strategies were developed using the nutrient balance method: CK (recommended NPK fertilization), BC (NPK + biochar), OF (NPK + organic fertilizer), and BF (NPK + 1/2 biochar + 1/2 organic fertilizer). Using different fertilization strategies, the eco-stoichiometry characteristics of the soil microbial biomass and enzyme activity; the bioavailability of C, N, and P; and the differences in PY were investigated, and the direct and indirect effects of these factors on PY were determined over a two-year period. The results showed that exogenous organic matter input could considerably affect the stoichiometric ratios of soil microbial biomass; C; N; P; the stoichiometric ratios of C-converting, N-converting, and P-converting enzyme activities (expressed as BG+CBH, NAG+LAP, and AP, respectively); and the integrated enzyme index (IEI). The IEI was the highest in BF, followed by OF, BC, and CK. A significant positive correlation was found between the microbial biomass C, N, and P and their corresponding converting enzyme activities (p < 0.05). The ln(BG+CBH):ln(NAG+LAP), ln(BG+CBH):lnAP, and ln(NAG+LAP):lnAP ratios were all higher than 1:1, but they approached 1:1 in the order of CK-BC-OF-BF. Compared to soil C and N, P-converting enzyme activity was the primary limiting factor for soil nutrient conversion in the study area. BF was less restricted by P and more balanced in its nutrient ratio. The microbial biomass C:N:P could affect PY in eight ways. (1) Microbial biomass C:N directly decreased PY, and microbial biomass C:P indirectly increased PY. (2) It could decrease C-converting enzyme activity, (3) decrease N availability to increase C-converting enzyme activity, (4) decrease P availability, or (5) decrease P availability to decrease the soil C:P-converting enzyme activity ratio. Microbial biomass N:P indirectly increased PY (6) by increasing the soil C:P-converting enzyme activity ratio, (7) by increasing C-converting enzyme activity, or (8) by increasing N availability to increase C-converting enzyme activity. Thus, BF is an effective strategy for regulating the soil microbiological fertility index; enhancing C, N, and P nutrient conversion; and increasing PY. The input of exogenous organic matter can alter the stoichiometric ratios of soil microbial biomass C, N, and P; the stoichiometric ratios of C-converting, N-converting, and P-converting enzyme activities; and nutrient availability, thus regulating PY. Microbial biomass N:P and soil C:P-converting enzyme activity ratios influence PY the most.

PurposeThe large-scale planting of potatoes leads to soil degradation, thus limiting the potato yield. An effective method of improving soil quality involves the combined application of biochar and organic fertilizer. However, the proportion of biochar and organic fertilizer at which potato yield can be improved, as well as the improvement mechanism, remain unclear.MethodsA combined application experiment involving biochar (B) and organic fertilizer (O) with four concentration gradients was conducted using the equal carbon ratio method. On this basis, rhizosphere soil fertility, bacterial community composition, and bacterial diversity in potato crops, as well as the potato yield difference under different combined application ratios, were investigated. Then, the direct and indirect effects of these factors on potato yield were analyzed.ResultsThe results suggest that soil fertility was improved by the combined application of biochar and organic fertilizer, with the best effect being achieved at a ratio of B:O=1:2. The dominant bacterial communities in the potato rhizosphere included Proteobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, and Bacteroidetes. When compared to the control, the relative abundance and diversity index of soil bacteria were significantly improved by the treatment at B:O=1:2, which exerted a stronger effect on improving the relative abundance of beneficial bacteria. Soil available phosphorus (AP), soil pH (SpH), and soil organic carbon (SOC) explained 47.52% of the variation in bacterial composition. Among them, the main factor was the content of soil available nutrients, while SpH generated the weakest effect. The bacterial diversity index showed a significant positive correlation with soil AP, SOC, available potassium (AK), total nitrogen (TN), and C/N ratio, and a significant negative correlation with SpH. Bacterial diversity directly affected the potato yield, while soil fertility indirectly affected potato yield by influencing the soil bacterial diversity.ConclusionThe combined application of biochar and organic fertilizer elevates potato yield mainly by improving the diversity of bacterial communities in potato rhizosphere soil, especially the combined application of biochar and organic fertilizer at a 1:2 ratio (biochar 0.66 t ha-1+organic fertilizer 4.46 t ha-1), which made the largest contribution to increasing potato yield.

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The potato planting area of Guizhou Province ranks second in China. However, due to factors such as climatic conditions and unbalanced fertilization, soil organic matter in potato fields is consumed rapidly and has a large deficit, which affects soil biological function and soil fertility. Biochar and organic fertilizer are effective ways to supplement foreign aid organic matter to improve soil quality. However, the differences in soil fertility and microbial community structure and their relationships under the conditions of organic fertilizer or biochar combined with chemical fertilizer are not clear. In this study, three treatments of conventional fertilization （NPK）, increased application of biochar （NPKB）, and increased application of organic fertilizer （NPKO） were set up to investigate the characteristics of potato rhizosphere soil, bacterial community composition, and diversity； to analyze the effects of these factors on the soil integrated fertility index； and to explore the direct and indirect effects of IFI on soil fertility and bacterial community structure differences between treatments and their driving factors. The results showed that soil pH, available phosphorus （AP）, available potassium （AK）, total nitrogen （TN）, organic carbon （SOC）, and C/N ratio were significantly higher in the NPKB and NPKO treatments than in the NPK treatment （P<0.05）. Soil IFI was greatest for NPKO, followed by NPKB and least for the NPK treatment. A total of 8 214 ASVs were obtained from all the soil samples, belonging to 26 phyla, 75 classes, 165 orders, 176 families, and 251 genera （excluding unidentified fungi）. Proteobacteria, Actinobacteria, and Chloroflexi were the dominant phyla, accounting for 54.85% of all ASVs. Compared to that in the NPK and NPKB treatments, the NPKO treatment had the highest bacterial diversity and number of significantly different taxa, and soil AN, AP, AK, SOC, TN, and IFI were significant correlates of bacterial diversity index （P<0.05）. Additionally, pH, TN, and SOC were significant influencers of bacterial taxa differences （P<0.05）, with importance ranked as TN （70.59%） &gt; SOC （49.42%） &gt; pH （27.08%）. Structural equations suggested that pH-related soil properties and bacterial community diversity were the direct pathways influencing IFI, and soil pH-related soil characteristics could also indirectly affect IFI by affecting bacterial Shannon diversity. These results indicate that soil fertility and bacterial community structure were significantly different and correlated between the biochar and organic fertilizer addition treatments and that pH and bacterial community diversity were the key factors influencing IFI, with the NPKO treatment in particular having the best effect on improving IFI. Considering the effect of soil fertilization and the functional group of bacteria, NPKO is the recommended combination for the best synergistic effect of soil fertilization, that is, N 150 kg·hm-2+P2O5 135 kg·hm-2+K2O 135 kg·hm-2+organic fertilizer 6.6 t·hm-2.

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.

Context or problem: Improving water and fertilizer use efficiency is an inevitable choice for sustainable potato production in North China. However, the regulation mechanism of potato water and nitrogen use efficiency under water-nitrogen coupling (W-N) regime is still unknown. Objective or research question: The objectives from a 3-year field experiment were (1) to assess the impact of W-N regimes on potato yield and water and nitrogen use efficiency, (2) to elucidate the soil microflora structure under W-N regimes, and (3) to determine the relationship between soil chemical properties, microflora structure, and potato water and nitrogen use efficiency. Methods: A three-year two-factor split-zone potato field experiment was conducted in arid and semi-arid regions of the Inner Mongolian Plateau, with irrigation [(rainfed (W0), optimized (soil-based) irrigation (W1), conventional irrigation (W2)] as the primary treatment and N fertilizer [no N (N0), chemical N (N1), 25 % manure substitution (N2)] as the secondary treatment. Results: Potato yield and water productivity followed N2 > N1 > N0, and partial nitrogen productivity and nitrogen agronomic efficiency followed N2 > N1 at the same irrigation level. Potato yield, nitrogen internal efficiency, partial nitrogen productivity and nitrogen agronomic efficiency first increased and then decreased, whereas water productivity gradually decreased with increasing irrigation levels under the same fertilization regime. Moreover, potato yield, soil total nitrogen, organic carbon, and microbial biomass carbon and nitrogen content peaked with the W1N2 regime. W-N regimes significantly influenced soil microbial community structure. Soil microbial alpha-diversity was less variable under W1 and N2 conditions. Soil bacterial network complexity and robustness were higher in W1 and W2 than in W0 regimes, whereas the opposite was true for fungi. The complexity and robustness of the soil bacterial and fungal network demonstrated for three fertilization regimes were higher in N1 and N2 than in N0 regimes. Neutral community model showed that soil microflora in W-N regime was mainly influenced by stochastic processes. PLSPM showed that organic substitution regime with optimized irrigation improves potato water and nitrogen use efficiency by regulating soil chemical properties rather than microflora structure. Conclusions: W1N2 regime synergizes well to improve potato water and N use efficiency and soil microflora stability, and organic substitution regime with optimized irrigation improves potato water and nitrogen use efficiency by regulating soil chemical properties.

针对内蒙古马铃薯主产区氮肥利用率普遍较低的现状,选择阴山南麓地区(乌兰察布市察哈尔右翼前旗)和阴山北麓地区(呼和浩特市武川县)两个典型生态区,研究不同施氮量下马铃薯叶片SPAD值变化、SPAD值与施氮量的关系以及与马铃薯产量的关系.结果表明:不同氮素处理下马铃薯叶片SPAD值随着生育期进程的推进呈现逐渐降低的趋势;随着施氮量的增加,各生育期马铃薯叶片SPAD值呈线性增加的趋势,马铃薯产量呈现先增后减的变化趋势,表明马铃薯叶片SPAD值与产量之间为二次函数关系,当叶片SPAD值超过一定值后,马铃薯增产幅度不再显著.武川县施氮量为225 kg·hm-2,产量达到最高为46.2 t·hm-2;前旗施氮量为350 kg·hm-2,产量达到最高为61.7 t·hm-2;马铃薯苗期、块茎形成期、块茎膨大前期、块茎膨大后期以及淀粉积累期阴山北麓地区的临界SPAD值分别为43.4、41.5、40.7、34.6、32.0,阴山南麓地区的临界SPAD值则分别为49.3、49.1、44.9、37.8、35.6;基于马铃薯叶片SPAD值建立了两个生态区的马铃薯主要生育期氮肥追施模型.

[目的]研究长期不同施肥对农牧交错带土壤酶活性、土壤化学性质及作物产量的影响,为旱作农田合理施肥和土壤培肥提供依据.[方法]长期定位试验位于内蒙古自治区农牧业科学院武川旱作试验站,始于2004 年,种植制度为马铃薯-油菜-莜麦轮作,一年一熟制.试验设置 8 个处理:CK(不施肥)、N(氮肥)、NP(氮磷肥)、NK(氮钾肥)、PK(磷钾肥)、NPK(氮磷钾肥)、M(羊粪)和NPKM(氮磷钾肥配施羊粪),2021 年种植作物为莜麦.调查了莜麦产量;采集各小区耕层(0-20 cm)土壤样品,分析磷酸酶(PA)、硫酸酯酶(SU)、β-葡糖苷酶(BG)、β-木糖苷酶(BX)、α-葡糖苷酶(AG)、β-纤维二糖苷酶(BCBH)、乙酰氨基葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)和土壤有机质(SOM)、碱解氮(AN)、有效磷(AP)、速效钾(AK)、pH等指标.通过主成分分析和冗余分析,探讨土壤酶活性分布特征及其与土壤化学性质和产量的关系.[结果]连续 18 年不同施肥处理均显著提高了作物产量和肥料对产量的贡献率,莜麦产量由高到低为NPKM>NPK>NP≈M>NK>N>PK>CK,施肥处理分别比CK增产 140.5%、108.7%、76.3%、71.1%、57.5%、48.2%和 20.8%,肥料对产量的贡献率分别为 58.4%、52.1%、43.3%、41.5%、36.4%、32.5%和 17.0%.长期施肥不同程度地提高了土壤有机质和速效氮、磷、钾含量,提高幅度均以NPKM处理最高,分别是CK的 5.35、2.29、10.07 和 4.89 倍.长期施肥显著影响了土壤pH,除PK处理外,土壤pH均显著低于CK,NPKM和NPK处理的土壤pH又显著低于除NP和NK外的其他施肥处理.NPK和M处理显著提高了参与碳(AG、BG、BX和BCBH)、氮(LAP和NAG)、磷(PA)和硫(SU)循环的酶活性.二者配施后的NPKM处理进一步提升了酶活性,其AG、BG、BX和BCBH分别是CK的 1.71、1.87、2.05 和 2.11 倍,LAP和NAG分别是CK的 1.97 和 2.24 倍,PA是CK的2.24 倍,SU是CK的 3.11 倍.土壤酶活性的变化主要由养分因子驱动,其中AN、SOM和AP是关键的决定因子,分别解释了酶活性变异的 75.1%、5.7%和 4.6%.[结论]在农牧交错带薯粮油轮作条件下,长期氮磷钾平衡施肥可增加莜麦产量,提高肥料对产量的贡献率,增加土壤养分含量和酶活性,降低pH.单施羊粪也有效提高了土壤养分含量和酶活性,但增产效果显著低于氮磷钾肥或氮磷肥,羊粪与氮磷钾肥配合提升作物产量和土壤质量的效果最佳,显著优于化肥和羊粪单独施用.

【Objective】 To clarify the water requirement law of sunflower and improve the coupling effect of water and nitrogen. 【Method】 A plot experiment was conducted to set three irrigation amounts, namely, rain-fed W0, supplementary W1 67.5 mm and conventional irrigation W2 135 mm, and three nitrogen application levels, namely, N0 (no nitrogen application), recommended nitrogen N1 135 kg/hm2 and excess nitrogen N2 270 kg/hm2, respectively. The effects of water and nitrogen coupling on yield, water consumption, water use efficiency, fertilizer utilization rate and water and nitrogen coupling effect of sunflower were studied. 【Result】 A plot experiment was conducted to set three irrigation amounts, namely, rain-fed W0, supplementary W1 67.5 mm and conventional irrigation W2 135 mm, and three nitrogen application levels, namely, N0 (no nitrogen application), recommended nitrogen N1 135 kg/hm2 and excess nitrogen N2 270 kg/hm2, respectively. The effects of water and nitrogen coupling on yield, water consumption, water use efficiency, fertilizer utilization rate and water and nitrogen coupling effect of sunflower were studied. 【Conclusion】 The suitable fertilization and irrigation mode for Sunflowers at the North Foot of Yinshan Mountain is the supplementary irrigation amount of 159.2~177.1 mm and the nitrogen rates of 166~218.3 kg/hm2. The 12-leaf - opening stage is the key period of water and fertilizer demand, and the supply of water and fertilizer should be ensured.

为探索内蒙古自治区河套灌区春小麦氮肥最佳施用量和施用方式,设置0、100、200、300 kg/hm24个施氮水平,同时设置一次性施肥和分次施肥两种方式,研究不同施肥模式对春小麦株高、叶绿素含量(SPAD值)、产量、氮肥农学利用率和偏生产力的影响.结果表明:不施肥和不施氮肥会严重影响春小麦生长发育和产量,株高、穗长、结实穗数、穗粒数、穗粒质量等指标数值较低;相同化肥用量下,采用一次性化肥施用方式时,春小麦长势较差,减产显著,同时春小麦氮肥农学利用效率降低13.7％,偏生产力降低8.7％.在此次设置的肥料用量区间,小麦产量与氮肥用量呈正相关,但当氮肥用量达到一定水平时产量增加幅度减小;春小麦株高、SPAD值与氮肥的用量呈正相关,随氮肥施用量的增加而增加,但当氮肥用量超过200 kg/hm2时,株高和SPAD值趋于稳定.

In China, manure is the most abundant organic fertilizer product. Understanding the changes in soil inorganic carbon (SIC) resulting from long-term manure fertilization is vital for accurately evaluating agricultural soil carbon stocks and predicting global change. However, a comprehensive and quantitative understanding of the impacts of long-term fertilization on SIC is lacking. This study was conducted to assess the effects of SIC changes in topsoil (0–20 cm), aggregates of kastanozems and influencing factors under the potato-rape-naked oats cultivation system after 16 years of long-term different fertilization in Wuchuan station. The results showed that 16 years of application of manure promoted the fixation of SIC by 2.25 t ha−1–3.25 t ha−1. As soil organic carbon (SOC) content, exchangeable calcium and magnesium concentrations in free coarse particulate organic matter (cfPOM) increased, the crystallization of carbonate was promoted at the aggregate level. The distribution proportion of free-coarse particulate organic matter (cfPOM) and microaggregates in mineral-related organic matter (iMOM) were also increased which affected the content of SIC. However, the pH value of NPKM treatment was lower than that of M treatment, which reduced the amount of carbonate crystallization. Thus, the application of manure alone was the best way to promote the fixation of SIC in topsoil rather than manure combined with chemical NPK fertilize. This work provides a new insight into the conversion of inorganic carbon, which is beneficial to promote the sequestration of inorganic carbon.

【Objective】 Soil water and nitrogen are the most important abiotic factors influencing plant growth and final yields. This paper aims to investigate the applicability of the Richards' equation for modeling growth, dry matter accumulation and yield formation of sunflower under different fertilizations and irrigations. 【Method】 The field experiment was conducted in 2021 in a dry area in the northern foot of Yinshan Mountain, Inner Mongolia. The variety Long Kui 27 used as the model plant; the field was mulched by plastic films. The split-plot experiment had three irrigation treatments: rain-fed plus irrigating 300 m3/hm2 of water just after the drilling to ensure seed germination (W1), replenishing irrigation by irrigating 900 m3/hm2 of water at seedling and budding stage, following the 300 m3/hm2 of pro-drilling irrigation (W2), and normal irrigation by irrigating a total 1 500 m3/hm2 of water at seedling, budding, flowering, and grain filling stages, respectively. In each irrigation treatment, there were three nitrogen fertilizations: 0 (N0), 135 (N1) and 270 kg/hm2 (N2). For each treatment, we used the Richards’ model to quantitatively analyze the changes in dry matter accumulation (DMA) and the impact of fertilization and irrigation on yield and yield formation. 【Result】 The Richards model was able to describe the dynamics of DMA. The impact of water and nitrogen on DMA and sunflower yield was obtained by the path analysis and the decision coefficient calculation. Optimized fertilization made the period of quick increase in DMA occur early, while excessive fertilization not only delayed the start of the quick increase in DMA but also shortened its duration. It was found that nitrogen application expedited the occurrence of the quick dry matter accumulation period, compared to no nitrogen application, while excessive nitrogen application not only brought the rapid growth period ending earlier, but also shortened it. Irrigation in the early growth stage delayed the onset of the rapid growth but increased the dry matter accumulation rate. In contrast, irrigation in the late growth stage delayed the end of the rapid growth period. 【Conclusion】 Our results provide guidance for optimal regulation of irrigation and fertilization to achieve high yield and improve water and nitrogen use efficiency of sunflower production in arid areas.

This study aims to explore the effects of long-term fertilization in arid chestnut soil, to reveal the changes of soil physicochemical and microbial properties under different fertilization schemes. Results would provide basis for reasonable fertilization and scientific evaluation of fertilization effects in the agro-pastoral zone of Inner Mongolia. Based on a long-term rotation fertilization positioning experiment（2004-2019） at Wuchuan Dryland Experimental Station in Inner Mongolia, we examined the effects of different fertilization schemes on the topsoil physicochemical and biological properties of chestnut calcareous soil in the agro-pastoral zone. The results showed that long-term organic manure combined with chemical fertilizer（NPK+OM） and single organic manure（OM） applications significantly reduced soil bulk density and increased soil porosity, while unbalanced fertilization（such as NP, NK, PK, N） and no fertilization（CK） showed an increasing trend in soil bulk density. Compared with CK, the contents of soil organic carbon, total nitrogen, alkaline hydrolysis nitrogen, available phosphorus and available potassium were increased in other treatments. The magnitudes of improvement for soil nutrients were ranked as follows: organic manure combined with chemical fertilizer ＞ organic manure ＞ chemical fertilizer balanced application ＞ chemical ferti-lizer unbalanced application ＞ no fertilization. In terms of soil microorganisms, soil bacterial abundance increased by 108.36%-118.92%, fungal abundance increased by 27.68%-50.46%, actinomycetic abundance increased by 35.43%-40.25% in NPK+OM. Long-term application of organic manure and balanced application of chemical fertilizer improved soil structure, soil nutrients, and microorganism abundance. In particular, the combination of organic manure and chemical fertilizer is the most effective. The application of reasonable ratio of nitrogen, phospho-rus and potassium significantly improved soil quality of arid chestnut soil in the agro-pastoral ecotone, unbalanced fertilization also improved soil properties, while no fertilization significantly degraded soil properties in the long term.

To explore the effects of different long-term fertilization treatments on soil microbial diversity and community structure in the drylands of an agro-pastoral ecotone, a long-term fertilization experiment at the Inner Mongolia cultivated land conservation science observation and experiment station, Ministry of Agriculture, and rural areas was taken as the research object. Four treatments, including no fertilizer (CK), single nitrogen fertilizer (NF), single chemical fertilizer (CF), and the combined application of organic manure and chemical fertilizer (CFM), were selected for the collection of 0-10 cm and 10-20 cm soil at potato maturity 16 years after the experiment (2019). High-throughput sequencing technology was used to assess the soil bacterial and fungal communities to explore the effects of different fertilization measures on soil quality from the perspective of microorganisms, and the partial least squares path model (PLS-PM) was used to reveal the key environmental driving factors of soil microbial community alternation and crop yield improvement in dryland during fertilization mode transformation. The results showed that:① the CF and CFM treatments significantly improved soil fertility, but the effect of the latter was significantly better than that of the former. Soil available nitrogen, available phosphorus, and available potassium in the CFM treatment increased by 131.9%-174.7%, 216.9%-283.3%, and 103.3%-109.3%, respectively, and organic matter and total nitrogen content also increased significantly. The CF treatment still maintained a high soil pH, whereas the NF treatment significantly decreased soil pH and had little effect in improving soil fertility. ② Compared with that under CK, the NF treatment significantly reduced the soil bacterial Chao1 and Shannon index, and the CFM treatment significantly increased the soil bacterial species richness, Chao1 index, and soil fungal Shannon index, whereas soil bacterial and fungal diversity in the CF treatment did not reach a significant difference level with CK. ③ The soil microbial community composition at 0-10 cm and 10-20 cm was similar. The CFM treatment increased the relative abundance of soil beneficial bacteria and decreased the relative abundance of pathogenic bacteria. The relative abundance of dominant bacteria such as Proteobacteria, Bacteroidetes, and Gemmatimonadetes increased. The relative abundances of Actinobacteria, Ascomycota, and Basidiomycota were decreased, whereas the NF and CF treatments showed the opposite trend. ④ PLS-PM analysis showed that with the gradual change in fertilization mode from CK→NF→CF→CFM, the driving factors affecting microbial community succession and yield increase were also changed from soil pH→soil NPK content→soil pH, SOM, and NPK content. In general, long-term fertilization had significant effects on soil chemical properties and microbial communities in drylands in the agro-pastoral ecotone. As the optimal fertilization choice, CFM was significantly better than NF and CF in improving soil fertility and inhibiting the growth of pathogenic microorganisms. The number of pathogens in long-term non-fertilization and unbalanced fertilization soil was significantly increased, and the risk of crop infection to indigenous diseases was increased. The research results can provide scientific reference for farmland nutrient balance management and soil microenvironment improvement of the agricultural ecosystem in the agro-pastoral ecotone in North China.

Long-term irrational fertilizer inputs affect soil nutrients conditions in the agro-pastoral ecotone of North China. However, the mechanisms by which biotic and abiotic factors are affected by different fertilizer types remain unclear. A 16-year, long-term fertilization experiment was conducted to explore how soil physicochemical properties and microbial communities respond to different fertilizer types at an experimental site in North China. The key environmental factors that drove changes in soil microbial communities were also determined. In September 2019, soils were collected from plots of four fertilizer treatments: 1) non-fertilization control (CK), 2) chemical fertilization only (CF), 3) organic manure fertilization only (M), and 4) chemical fertilization plus organic manure (CFM). Compared with CK, soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium contents were higher in M and CFM, whereas soil pH was significantly lower in CF. Abundances of dominant soil bacterial phyla Proteobacteria, Bacteroidetes, and Gemmatimonadetes were higher in M and CFM than CK. Abundances of dominant soil fungal phyla Ascomycota was lower in CFM than in other treatments. The pathogenic fungi Fusarium, Paramyrothecium, Cladosporium, and Alternaria had the highest abundances in CK and CF, whereas abundances of the beneficial fungi Mortierella were significantly higher in M and CFM than in CF and CK. According to partial least squares path modeling, differences in fertilizer types had direct positive effects on fungal communities but little effect on bacterial communities. Overall, CFM maintained higher soil fertility and a healthy ecosystem because it increased beneficial microorganisms and inhibited pathogenic microorganisms, whereas CF increased the risk of crop infection with soil-borne diseases. The study provided a better understanding of how long-term fertilization affects microbial community composition and their associated ecosystem functions.

为探讨有机硅土壤调理剂和有机硅功能底肥对河套灌区盐碱土壤碱化度、养分有效性及作物增产效果,在内蒙古巴彦淖尔市五原县通过采取田间小区试验设置3个处理:(1)有机硅土壤调理剂45 kg/hm2,有机硅功能肥7.5 kg/hm2;(2)有机硅土壤调理剂75 kg/hm2,有机硅功能底肥5 kg/hm2;(3)磷酸二铵16.3 kg/hm2,氯化钾16.5 kg/hm2,尿素11.5 kg/hm2.结果表明:施用有机硅土壤调理剂后,可增加向日葵百粒重,进而增加向日葵产量,且随着有机硅土壤调理剂施用量的增加,向日葵产量呈上升趋势,施用量为75 kg/hm2时,增产幅度为9.0％,增产效果显著.在基施有机硅土壤调理剂45 kg/hm2和追施有机硅功能肥7.5 kg/hm2的前提下经济效益最佳,施用有机硅土壤调理剂后,可增加土壤有效养分,降低土壤pH、含盐量、碱化度和容重,可有效提高耕地质量和修复障碍层次.

[目的]明确河套灌区向日葵生产中有机肥替代化肥的施用效果及适宜替代比例.[方法]试验在内蒙古巴彦淖尔市临河区进行,设100％有机氮(100％M)、25％化肥氮+75％有机氮(75％M)、50％化肥氮+50％有机氮(50％M)、75％化肥氮+25％有机氮(25％M)、化肥优化(NE)、不施氮肥(CK)6个处理,建立有机肥替代比例与向日葵产量的回归方程,分析不同有机肥替代比例对向日葵籽实粗脂肪含量、脂肪酸组成、籽粒锈斑及氮肥利用率和土壤养分的影响.[结果]25％M处理向日葵产量最高,为5626.47 kg/hm2,比CK显著增产30.70％(P<0.05).回归分析表明,向日葵生产中有机肥最佳替代比例为18.86％.随着有机肥替代比例的增加向日葵籽实的不饱和脂肪酸比例有所提高;有机肥替代化肥向日葵籽实的粗脂肪含量略有增加、籽粒锈斑的病情指数和发病率降低;有机肥替代化肥可以提高肥效,25％M处理的氮肥利用率和农学效率最高,分别较NE处理提高4.85个百分点和0.89 kg/kg;土壤有机质、速效磷和速效钾含量随有机肥替代比例增加有增加的趋势.[结论]有机肥替代最适比例为18.86％时,向日葵产量最高,籽实粗脂肪和不饱和脂肪酸含量增加,籽粒锈斑的病情指数和发病率降低,并可以提高氮肥利用率,培肥地力.