Basic Soil Productivity of Spring Maize in Black Soil Under Long-Term Fertilization Based on DSSAT Model

Increasing basic farmland soil productivity has significance in reducing fertilizer application and maintaining high yield of crops. In this study, we defined that the basic soil productivity （BSP） is the production capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local environment and field management. Based on 22-yr （1990-2011） long-term experimental data on black soil （Typic hapludoll） in Gongzhuling, Jilin Province, Northeast China, the decision support system for an agro-technology transfer （DSSAT）-CERES-Maize model was applied to simulate the yield by BSP of spring maize （Zea mays L.） to examine the effects of long-term fertilization on changes of BSP and explore the mechanisms of BSP increasing. Five treatments were examined： （1） no-fertilization control （control）; （2） chemical nitrogen, phosphorus, and potassium （NPK）; （3） NPK plus farmyard manure （NPKM）; （4） 1.5 time of NPKM （1.5NPKM） and （5） NPK plus straw （NPKS）. Results showed that after 22-yr fertilization, the yield by BSP of spring maize significantly increased 78.0, 101.2, and 69.4% under the NPKM, 1.5NPKM and NPKS, respectively, compared to the initial value （in 1992）, but not significant under NPK （26.9% increase） and the control （8.9% decrease）. The contribution percentage of BSP showed a significant rising trend （P〈0.05） under 1.5NPKM. The average contribution percentage of BSP among fertilizations ranged from 74.4 to 84.7%, and ranked as 1.5NPKM〉NPKM〉NPK〉NPKS, indicating that organic manure combined with chemical fertilizers （I.5NPKM and NPKM） could more effectively increase BSP compared with the inorganic fertilizer application alone （NPK） in the black soil. This study showed that soil organic matter （SOM） was the key factor among various fertility factors that could affect BSP in the black soil, and total N, total P and/or available P also played important role in BSP increasing. Compared with the chemical fertilization, a balanced chemical plus manure or straw fertilization （NPKM or NPKS） not only increased the concentrations of soil nutrient, but also improved the soil physical properties, and structure and diversity of soil microbial population, resulting in an iincrease of BSP. We recommend that a balanced chemical plus manure or straw fertilization （NPKM or NPKS） should be the fertilization practices to enhance spring maize yield and improve BSP in the black soil of Northeast China.

Long-Term Fertilization Effect on Fertility of Salt-Affected Soils

The long-term effects of annual fertilizer applications on the fertility of salt-affected soils under the rotation system ofwheat (Triticum aestivum L.) and maize (Zea mays L.) are not well documented. In 1984, research plots were establishedto test the effects of annual applications of different rates of nitrogen (N) and phosphorus (P) fertilizers on the fertilityof a salt-affected soil (Typic Ustochrept) at the Quzhou Experimental Station, Quzhou County, Hebei Province, China.In October 2001, composite soil samples (0-20 and 20-40 cm) were collected from each plot and analyzed for soil fertilityindices. Seventeen years of N and P fertilizer applications increased the soil organic matter (SOM) in the surface layer.With combined N, 270 (N1) and 540 (N2) kg N ha-1 year-1, and P, 67.5 (P1) and 135 (P2) kg P2O5 ha-1 year-1,fertilizer applications, total soil N mostly significantly decreased (P < 0.05). Soil total P in the 0-20 cm layer of theP2 treatment significantly (P < 0.05) increased as compared to those of the other treatments. Rapidly available P (RP)in the 0-20 cm layer of the N1P2 treatment was significantly higher than those in the other treatments except the P2treatment; and RP in the 0-20 cm layer of the P2 treatment significantly increased as compared to those of the othertreatments except the P1 and N1P2 treatments. RP in the subsurface soil layer (20-40 cm) of the P2 treatment (4.2 mg Pkg-1) was significantly (P < 0.05) higher than those in the other treatments. Nevertheless, long-term N fertilization didnot significantly increase the alkali-hydrolyzable N in the soil. However, in the salt-affected surface soils the applicationof combined N and P fertilizers over 17 years significantly (P < 0.05) decreased rapidly available potassium (K). Theresults suggested that while under long-term fertilizer applications some soil fertility parameters could be maintained orenhanced, careful monitoring of soil fertility was necessary as other nutrients such as K could become depleted.

Effects of long-term organic fertilization on soil microbiologic characteristics,yield and sustainable production of winter wheat

We investigated the soil microbiologic characteristics, and the yield and sustainable production of winter wheat, by conducting a long-term fertilization experiment. A single application of N, P and K （NPK） fertilizer was taken as the control （CK） and three organic fertilization treatments were used： NPK fertilizer＋pig manure （T1）, NPK fertilizer＋straw return （T2）, NPK fertilizer＋pig manure＋straw return （T3）. The results showed that all three organic fertilization treatments （T1, T2 and T3） significantly increased both soil total N （STN） and soil organic carbon （SOC） from 2008 onwards. In 2016, the SOC content and soil C/N ratios for T1, T2 and T3 were significantly higher than those for CK. The three organic fertilization treatments increased soil microbial activity. In 2016, the activity of urease （sucrase） and the soil respiration rate （SRS） for T1, T2 and T3 were significantly higher than those under CK. The organic fertilization treatments also increased the content of soil microbial biomass carbon （SMBC） and microbial biomass nitrogen （SMBN）, the SMBC/SMBN ratio and the microbial quotient （qMB）. The yield for T1, T2 and T3 was significantly higher than that of CK, respectively. Over the nine years of the investigation, the average yield increased by 9.9, 13.2 and 17.4% for T1, T2 and T3, respectively, compared to the initial yield for each treatment, whereas the average yield of CK over the same period was reduced by 6.5%. T1, T2, and T3 lowered the coefficient of variation （CV） of wheat yield and increased the sustainable yield index （SYI）. Wheat grain yield was significantly positively correlated with each of the soil microbial properties （P〈0.01）. These results showed that the long-term application of combined organic and chemical fertilizers can stabilize crop yield and make it more sustainable by improving the properties of the soil.

Chemical fertilizers could be completely replaced by manure to maintain high maize yield and soil organic carbon(SOC)when SOC reaches a threshold in the Northeast China Plain

The combined use of chemical and organic fertilizers is considered a good method to sustain high crop yield and enhance soil organic carbon （SOC）, but it is still unclear when and to what extent chemical fertilizers could be replaced by organic fertilizers. We selected a long-term soil fertility experiment in Gongzhuling, Northeast China Plain to examine the temporal dynamics of crop yield and SOC in response to chemical nitrogen, phosphorus, and potassium （NPK） fertilizers and manure, applied both individually and in combination, over the course of three decades （1980-2010）. We aimed to test 1） which fertilizer application is the best for increasing both maize yield and SOC in this region, and 2） whether chemical fertilizers can be replaced by manure to maintain high maize yield and enhance SOC, and if so, when this replacement should be implemented. We observed that NPK fertilizers induced a considerable increase in maize yield in the first 12 years after the initiation of the experiment, but manure addition did not. In the following years, the addition of both NPK fertilizers and manure led to an increase in maize yield. SOC increased considerably in treatments with manure but remained the same or even declined with NPK treatments. The increase in maize yield induced by NPK fertilizers alone declined greatly with increasing SOC, whereas the combination of NPK and manure resulted in high maize yield and a remarkable improvement in SOC stock. Based on these results we suggested that NPK fertilizers could be at least partially replaced by manure to sustain high maize yield after SOC stock has reached 41.96 Mg C ha^-1 in the Northeast China Plain and highly recommend the combined application of chemical fertilizers and manure （i.e., 60 Mg ha^-1）.

Effect of Long-Term Application of K Fertilizer and Wheat Straw to Soil on Crop Yield and Soil K Under Different Planting Systems

Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.

Interactions between phosphorus availability and microbes in a wheat–maize double cropping system:A reduced fertilization scheme

Mechanisms controlling phosphorus(P) availability and the roles of microorganisms in the efficient utilization of soil P in the wheat–maize double cropping system are poorly understood.In the present study,we conducted a pot experiment for four consecutive wheat–maize seasons(2016–2018) using calcareous soils with high(30.36 mg kg^(–1)) and low(9.78 mg kg^(–1)) initial Olsen-P content to evaluate the effects of conventional P fertilizer application to both wheat and maize(Pwm) along with a reduced P fertilizer application only to wheat(Pw).The microbial community structure along with soil P availability parameters and crop yield were determined.The results showed that the Pw treatment reduces the annual P input by 33.3% without affecting the total yield for at least two consecutive years as compared with the Pwm treatment in the high Olsen-P soil.Soil water-soluble P concentrations in the Pw treatment were similar to those in the Pwm treatment at the 12-leaf collar stage when maize requires the most P.Furthermore,the soil P content significantly affected soil microbial communities,especially fungal communities.Meanwhile,the relative abundances of Proteobacteria and alkaline phosphatase(ALP) activity of Pw were significantly higher(by 11.4 and 13.3%) than those of Pwm in soil with high Olsen-P.The microfloral contribution to yield was greater than that of soil P content in soil with high Olsen-P.Relative abundances of Bacillus and Rhizobium were enriched in the Pw treatment compared with the Pwm treatment.Bacillus showed a significant positive correlation with acid phosphatase(ACP) activity,and Rhizobium displayed significant positive correlations with ACP and ALP in soil with high Olsen-P,which may enhance P availability.Our findings suggested that the application of P fertilization only to wheat is practical in high P soils to ensure optimal production in the wheat and maize double cropping system and that the soil P availability and microbial community may collaborate to maintain optimal yield in a wheat–maize double cropping system.

Long-term organic and inorganic fertilizations enhanced basic soil productivity in a fluvo-aquic soil

The improvement of soil productivity depends on a rational input of water and nutrients, optimal field management, and the increase of basic soil productivity（BSP）. In this study, BSP is defined as the productive capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local field management. Based on 19-yr data of the long-term agronomic experiments（1989–2008） on a fluvo-aquic soil in Zhengzhou, Henan Province, China, the decision support system for agrotechnology transfer（DSSAT ver. 4.0） crop growth model was used to simulate yields by BSP of winter wheat（Triticum aestivium L.） and summer maize（Zea mays L.） to examine the relationship between BSP and soil organic carbon（SOC） under long-term fertilization. Five treatments were included：（1） no fertilization（control）,（2） nitrogen, phosphorus and potassium fertilizers（NPK）,（3） NPK plus manure（NPKM）,（4） 1.5 times of NPKM（1.5NPKM）, and（5） NPK plus straw（NPKS）. After 19 yr of treatments, the SOC stock increased 16.7, 44.2, 69.9, and 25.2% under the NPK, NPKM, 1.5NPKM, and NPKS, respectively, compared to the initial value. Among various nutrient factors affecting contribution percentage of BSP to winter wheat and summer maize, SOC was a major affecting factor for BSP in the fluvo-aquic soil. There were significant positive correlations between SOC stock and yields by BSP of winter wheat and summer maize（P〈0.01）, and yields by BSP of winter wheat and summer maize increased 154 and 132 kg ha^（–1） when SOC stock increased 1 t C ha^（–1）. Thus, increased SOC accumulation is a crucial way for increasing BSP in fluvo-aquic soil. The manure or straw combined application with chemical fertilizers significantly enhanced BSP compared to the application of chemical fertilizers alone.

Organic amendments increase corn yield by enhancing soil resilience to climate change

A 22-year field experiment was conducted in Gongzhuling, Jilin province, China to investigate corn yield response to fertilization practice. Compared to an unfertilized control(CK), all fertilization treatments, including inorganic nitrogen fertilizer only(N), balanced inorganic fertilizers(NPK), NPK plus corn straw(SNPK), and NPK plus farmyard manure(MNPK), resulted in significant increases in corn yield. However, only organic matter amendments sustained increasing yield trends, with annual rates of 0.137 and 0.194 t ha-1for the SPNK and MNPK treatments, respectively(P < 0.05). During the 22 years, the daily mean, maximum and minimum temperatures increased by 0.50, 0.53, and 0.46 °C per decade, whereas precipitation displayed no significant change but showed large seasonal variation. According to a regression analysis, increased air temperature exerted positive effects on corn yields under the SNPK and the MNPK treatments. Under both treatments,soil organic carbon contents and soil nutrient availabilities increased significantly compared to their initial levels in 1990, whereas soil bulk density and total porosity changed slightly under the two treatments, which showed higher soil water storage than other treatments. In contrast, significant increases in soil bulk density and decreases in soil total porosity and soil nutrient availability were observed under the CK, N and NPK treatments. The contributions of soil fertility to corn yield were 28.4%, 37.9%, 38.4%, 39.0%,and 42.9% under CK, N, NPK, SNPK, and MNPK treatments, respectively, whereas climate changes accounted for 27.0%, 14.6%, 12.4%, 11.8%, and 10.8%. These results indicate that, in Northeast China, organic matter amendments can mitigate negative and exploit positive effects of climate change on crop production by enhancing soil quality.

聚脲甲醛缓释肥减量深施对小麦和玉米产量及氮肥吸收率的影响

为了探究聚脲甲醛缓释肥(PF)减量深耕对小麦和玉米作物产量、氮肥利用效率以及矿质养分迁移的影响,设置对照(CK)、尿素+旋耕(OPTX)、尿素+深耕(OPTS)、PF+旋耕(PFX)和PF+深耕(PFS)5个处理,在豫南砂姜黑土小麦、玉米农田开展大区试验。结果表明,对比传统尿素(OPT)处理,PF处理小麦、玉米产量显著高于OPT处理,尤其PFS处理较OPTX处理小麦和玉米季产量分别高12%和6.4%,较OPTS处理分别高3.4%和1.8%;与产量不同,PFS处理仅显示玉米季氮肥利用率(NUE)高于OPTX和OPTS处理,而小麦季NUE甚至低于OPTS处理,这可能与PF在小麦季深耕条件下养分释放速度慢有关。对比两种耕作方式,发现PFS处理小麦季产量与PFX处理产量无显著差别,而玉米季产量显著高于PFX处理;与产量不同,PFS处理小麦季NUE显著低于PFX处理,而玉米季无显著差别,这可能与玉米季更适宜的气象条件和小麦季PF养分的后续释放有关。对比土壤铵态氮(NH_(4)^(+)-N)、硝态氮(NO_(3)^(-)-N)残留量和总氮浓度,发现作物收获后,PFS处理0~30和30~60 cm土层NH_(4)^(+)-N残留量与PFX处理无显著差异,NO_(3)^(-)-N残留量显著低于PFX处理,而总氮含量略高于PFX处理,这可能与PF处理在小麦季深耕条件下氮素未释放完全有关。总而言之,依据作物的产量和氮肥利用效率,聚脲甲醛缓释肥在深耕条件下显示出更高的产量效益和增产潜势,尤其玉米季作物吸氮量、产量和NUE有了显著提升,值得被推荐。

长期大量施用污泥堆肥显著提升华北地区粮食作物产量和土壤碳汇效应

【目的】阐明长期不同用量质量达标的污泥堆肥配施化肥对华北地区冬小麦-夏玉米轮作体系作物产量,以及耕层土壤有机碳储量(SOCS)和全氮(TN)、全磷(TP)、全钾(TK)含量的影响,为污泥高效资源化利用及农业绿色可持续发展提供理论依据。【方法】于北京市昌平区,开展污泥堆肥(SW)与化肥配施定位试验(2008—2020年),种植制度为冬小麦-夏玉米轮作,试验设置5个处理:100%尿素(N)、50%WS+50%尿素(0.5SW+0.5N)、100%SW+50%尿素(SW+0.5N)、200%SW+50%尿素(2SW+0.5N)、400%SW+50%尿素(4SW+0.5N)处理。小麦、玉米收获后,调查籽粒和秸秆产量,0—20 cm土层土壤有机质和氮磷钾含量,并计算土壤固碳效率。【结果】随着污泥堆肥用量的增加,小麦和玉米籽粒和秸秆产量逐渐增加,与N处理相比,0.5SW+0.5N处理小麦、玉米籽粒和秸秆多年平均产量无显著差异,SW+0.5N、2SW+0.5N和4SW+0.5N处理下小麦籽粒产量分别增加了6.97%、14.88%和17.94%,玉米籽粒产量分别增加了8.43%、11.77%和15.38%。土壤中有机碳储量、全氮、全磷、全钾含量在0.5SW+0.5N、SW+0.5N、2SW+0.5N和4SW+0.5N处理下较N处理明显提升。同时,土壤中有机碳储量、全氮、全磷和全钾含量随污泥堆肥用量的增加而显著增加(P<0.05)。N、0.5SW+0.5N、SW+0.5N、2SW+0.5N和4SW+0.5N处理下,土壤全氮含量多年平均值分别为1.07、1.26、1.56、1.93和2.73 g/kg,全磷含量分别为1.19、1.67、2.37、3.27、4.11 g/kg,全钾含量分别为18.60、19.06、19.85、20.07、21.19 g/kg。【结论】与单施尿素相比,以质量达标的污泥堆肥替代50%尿素(0.5SW+0.5N)不会影响小麦、玉米籽粒和秸秆产量,而且可以提升土壤肥力。在尿素用量减半条件下,增加污泥堆肥用量可显著提高小麦、玉米籽粒产量和土壤肥力,特别是在污泥堆肥氮用量为尿素氮用量的4倍时,小麦和玉米可稳定增产15%~18%,并且由于高量污泥堆肥的长期施用极大地提升了土壤中有机碳、全氮、全磷和全钾的储量,保证了产量的可持续性和土壤的碳汇效应。

有机物料与化肥长期配施对小麦玉米轮作潮土细菌群落和酶活性的影响

【目的】研究有机物料与化肥长期配施对土壤细菌群落和酶活性的影响,揭示土壤养分、胞外酶活性与细菌群落之间关系,为制定潮土区小麦玉米轮作制度下长期且合理的施肥策略提供理论依据。【方法】连续10年的定位试验,设置不施肥(NF)、单施化肥(NPK)、化肥配合秸秆还田(NPKS)、50%的化肥配施6000 kg·hm-2猪粪(NPKP)和50%的化肥配施6000 kg·hm-2牛粪(NPKC)等5个处理。【结果】(1)有机物料与化肥长期配施(NPKS、NPKP和NPKC)可显著提高土壤肥力和胞外酶活性,其中NPKC处理提升效果最为显著,土壤有机质、全氮、碱解氮、有效磷含量和碱性磷酸酶活性较NPK处理提升幅度为13.8%—15.4%、9.7%—15.5%、7.2%—15.9%、13.6%—38.5%和2.5%—13.1%。(2)有机物料与化肥长期配施显著改变了细菌群落结构和组成。与NPK处理相比,小麦季NPKS处理显著上调物种为Aggregatilinea和Parachlamydia,NPKP处理显著提高Pseudomonas、Nonomuraea和Flexilinea丰度,NPKC处理仅Luteitalea丰度显著升高。玉米季NPKS处理显著上调的物种为Phycisphaera和Syntrophothermus,NPKP处理显著提高Gemmatimonas丰度;NPKC处理Aquipuribacter和Desulfosoma丰度显著升高。(3)功能预测结果表明,长期有机物料与化肥配施较单施化肥对土壤碳、氮循环功能有促进作用,尤其NPKC处理对硝化作用、尿素溶解、芳香族化合物的降解、木聚糖分解、纤维素降解作用均有较强的影响。(4)蒙特尔分析表明,土壤pH是潮土细菌群落结构和生态功能的主要调控因素。【结论】有机物料与化肥长期配施(尤其是化肥配施牛粪)可提高土壤肥力和胞外酶活性,增加有益菌群丰度,显著改变细菌群落结构和组成,有利于碳、氮、磷循环,从而促进潮土形成适合作物和细菌生长的环境。

有机肥替代化肥对砂姜黑土区小麦-玉米轮作系统N_(2)O排放的影响

【目的】探究有机肥替代化肥条件下砂姜黑土区小麦-玉米轮作系统N_(2)O排放特征及与土壤环境因子的关系,为实现农田温室气体减排提供理论依据。【方法】以砂姜黑土区小麦-玉米轮作系统为研究对象,采用静态箱-气相色谱法与常规土壤参数分析相结合,研究不施肥(CK)、常规施肥(CF)、有机肥氮替代20%化肥氮及有机肥氮替代40%化肥氮(R2FM及R4FM,有机肥于小麦季施用)对小麦-玉米轮作系统N_(2)O排放的影响及与关键驱动因子的关系。【结果】R2FM及R4FM处理小麦产量显著高于CF处理,增幅分别为12.2%和10.2%,而不同施肥处理之间玉米产量无显著差异。CK、CF、R2FM及R4FM处理周年N_(2)O平均排放通量分别为5.9、50.3、43.9及39.6μg·m^(-2)·h^(-1),其中小麦季为3.1、23.6、25.0及26.4μg·m^(-2)·h^(-1),玉米季为8.8、77.0、62.8及52.9μg·m^(-2)·h^(-1);不同施肥处理下N_(2)O排放通量与土壤NO_(3)^(-)-N含量呈极显著正相关,同时还与小麦季土壤温度、玉米季土壤含水量呈显著或极显著正相关。CF、R2FM及R4FM处理周年N_(2)O累积排放量分别为2.38、2.44及2.53 kg·hm-2,较CK处理(0.56 kg·hm-2)显著增加325%—354%,N_(2)O-N排放系数为0.40%—0.44%,但CF、R2FM及R4FM处理之间周年N_(2)O累积排放量、N_(2)O-N排放系数均无显著差异。不同施肥处理下季节性N_(2)O累积排放量存在差异,与CF处理相比,R2FM及R4FM处理在小麦季N_(2)O累积排放量分别显著提高28.3%和62.6%,且二者N_(2)O-N排放系数(0.35%和0.41%)显著增加,而在玉米季N_(2)O累积排放量分别显著降低15.8%和33.8%;N_(2)O累积排放量与小麦季土壤全氮、碱解氮、微生物量碳含量及玉米季土壤全氮含量呈显著或极显著正相关,而与玉米季土壤有机碳含量呈显著负相关。【结论】在有机肥氮替代化肥氮条件下,优化小麦季施肥管理是减少砂姜黑土区小麦-玉米轮作系统N_(2)O排放的关键。

氮肥减施对黄褐土区小麦——玉米轮作体系产量和氮素吸收利用的影响

为了明确黄褐土区小麦—玉米轮作体系最佳的氮肥减施量,2018—2020年在黄褐土区设置不施氮肥(CK)、常规施肥(FP,施氮225 kg/hm^(2))、优化施肥(CF,施氮180 kg/hm^(2))、常规施肥基础上减氮10%(90%FP,施氮202.5 kg/hm^(2))、常规施肥基础上减氮20%(80%FP,施氮180 kg/hm^(2))、常规施肥基础上减氮30%(70%FP,施氮157.5 kg/hm^(2))、控失尿素和普通尿素7∶3配施(CRU,施氮180 kg/hm^(2))共7个处理,探讨氮肥减施对小麦—玉米轮作体系产量和氮肥吸收利用的影响。结果表明,所有施氮处理中,2个轮作周年,CF处理小麦、玉米产量均最高,CRU处理次之,两者无显著差异。与FP处理相比,在减氮20%条件下,2个轮作周年,CF处理和CRU处理小麦产量分别提高3.62%和2.57%,玉米产量分别提高3.53%和1.85%;80%FP处理小麦、玉米产量均降低,但不显著。减氮30%处理小麦、玉米产量均较FP处理明显减产。2个轮作周年,CF处理和CRU处理土壤中有机质、全氮和水解氮含量较高,高于其他处理,但两者差异不显著,70%FP处理总体上较FP处理显著降低土壤水解氮含量。2个轮作周年,CF处理和CRU处理小麦、玉米的氮肥回收率、氮肥农学效率和氮肥偏生产力均较高,两者差异不显著,但均显著高于FP处理。其中,CRU处理小麦和玉米的氮肥回收率分别提高32.1%~50.8%和41.7%~44.2%,氮肥农学效率分别提高31.7%~35.6%和29.5%~31.9%,氮肥偏生产力分别提高27.4%~28.9%和26.9%~27.7%。综上,黄褐土区小麦—玉米轮作体系中,减氮20%条件下优化施肥、控失尿素和普通尿素7∶3配施均能提高作物产量和氮素利用效率,而减氮30%则存在减产风险。综合考虑,控失尿素和普通尿素7∶3配施并一次性施肥为黄褐土区小麦—玉米轮作区的最佳施肥措施。

秸秆还田对关中地区麦玉轮作田N_(2)O排放的短期效应

【目的】分析环境因子和土壤N_(2)O排放对短期秸秆还田的响应,以更准确地评价化肥施用下短期秸秆还田的增减排效益。【方法】于2020—2021年在关中地区开展了小麦–玉米轮作田间试验。采取双因素裂区设计,主处理为秸秆还田(W1)与不还田(W0),副处理为不施肥(W1、W0)、施氮肥(W1N、W0N)和施氮磷肥(W1NP、W0NP)。测定了土壤含水量、温度、NO_(3)^(-)-N、NH_(4)^(+)-N、速效磷含量及N_(2)O排放通量,调查了作物产量,并探讨了土壤N_(2)O排放与环境因子之间的关系。【结果】相比W0,W1处理土壤含水量提高了1.1%~16.2%;W1N处理的土壤NO_(3)^(-)-N含量峰值较W0N高17.6%~30.5%。4个施肥处理的土壤NO_(3)^(-)-N和NH_(4)^(+)-N含量随生育时期推进先迅速上升,然后缓慢下降,施氮肥处理的土壤NO_(3)^(-)-N峰值比施氮磷肥处理高17.0%~20.8%。W1NP与W0NP处理土壤的速效磷含量随生育期推进先上升后缓慢下降,平均速效磷含量显著高于处理W0、W1、W0N和W1N(P<0.05)。冬小麦季和夏玉米季分别在施肥后第6和第12天土壤N_(2)O排放通量达到峰值。W1N、W1NP的土壤N_(2)O排放峰值分别比W0N、W0NP高5.0%和38.5%,全年累计排放量分别比W0N、W0NP高291.13和379.99 g/hm^(2)(P<0.05);W1N处理的土壤N_(2)O全年累计排放量比W1NP处理高298.14 g/hm^(2),W0N处理的土壤N_(2)O全年累计排放量比W0NP高386.99 g/hm^(2),施氮磷肥处理的排放峰值比施氮肥处理低2.43%~54.67%。相关性分析发现,N_(2)O排放通量与土壤温度、含水量、NO_(3)^(-)-N、NH_(4)^(+)-N、速效磷含量呈极显著正相关(P<0.01)。各处理N_(2)O排放强度表现为:相同秸秆还田条件下,施氮肥>施氮磷肥>不施肥处理;相同施肥条件下,秸秆还田>不还田处理。【结论】不论是否秸秆还田,氮磷肥配施均提高了土壤速效磷含量,降低了NO_(3)^(-)-N峰值,因而降低了N_(2)O年累积排放量。秸秆还田后短期内虽然也提高了土壤速效磷含量,但其较高的土壤含水量和NO_(3)^(-)-N含量导致更高的N_(2)O排放通量和农田N_(2)O累计排放量。因此,评价秸秆还田在农业可持续发展中的生态与生产效益时,也应考虑其还田后短期存在的不利影响。

麦玉复种连作田土壤性状及周年产量对耕作与施肥的响应

保护性耕作与有机肥施用是黄土高原旱作农业区缓解生态脆弱问题的有效解决手段之一,合理的耕作与施肥措施对山西中部旱区实现麦玉一年两熟具有重要意义。以黄土高原旱作农田为研究对象,采用裂区试验设计,主区为3种耕作方式(深翻(DT)、深松(SS)、免耕(NT)),副区为4种施肥水平(不施肥对照(CK)、全量化肥(CF)、50%化肥+50%有机肥(OF)、全量有机肥(OM)),探究不同耕作与施肥方式下土壤容重、速效养分及麦玉周年产量的变化特征。结果表明,有机肥施用后SS、NT处理0~20 cm土壤容重较DT处理有所下降,其中小麦季SS+OF处理下耕层土壤容重为1.13 g/cm^(3),显著低于DT+OF处理。整个周年复种连作体系中,以NT+OM处理土壤质量含水量最高,较其他施肥处理平均升高7.88百分点;SS+OM处理下土壤的三相比更为理想,三相比偏离值偏低。3种耕作方式下,碱解氮与有效磷含量大小总体呈现OM>OF>CF>CK的趋势,速效钾含量与施肥方式存在极显著关系,其中CF处理下含量最高;玉米季增施有机肥较单施化肥显著提高了糯玉米鲜穗产量,但有机肥施用比例间的差异并不显著,SS+OM处理下麦玉周年产量最高,达19145 kg/hm 2。综上,该试验条件下,SS、NT耕作方式与有机肥施用结合可明显改善土壤的物理性状,碱解氮与有效磷含量也有一定程度的提升,其中,SS+OM处理更有利于黄土高原地区麦玉周年复种连作田产量的提升。

玉米秸秆还田与氮肥运筹对砂姜黑土理化性质和小麦产量的影响

为研究不同氮肥基追比例运筹下玉米秸秆直接还田对砂姜黑土理化性质和小麦产量的影响,为确定当地适宜耕作和秸秆还田模式提供理论依据,采用两因素裂区试验,因素一为玉米秸秆(S)直接还田(5000kg/hm^(2))和玉米秸秆不还田;因素二为氮肥基肥-分蘖肥-穗肥施用比例。设3种基肥:分蘖肥:穗肥比例(70-30-0、60-30-10和50-30-20),共6个处理,分别为N_(70-30-0)、N_(70-30-0)+S、N_(60-30-10)、N_(60-30-10)+S、N_(50-30-20)和N_(50-30-20)+S。小麦收获后采集0~20cm代表性土壤样品分析理化性状,包括含水率、pH、有机质、氮磷钾养分含量,测定小麦株高、穗长、穗粒数、千粒重、籽粒产量。结果显示,与不还田相比,3种氮肥运筹下玉米秸秆还田后土壤pH降低,土壤含水率、有机质、有效磷、速效钾含量明显提高;各处理小麦籽粒产量各不相同,N_(50-30-20)+S处理小麦籽粒产量最高;相关性分析表明小麦产量与穗粒数(r=0.837)和结实率(r=0.885)呈5%显著正相关,秸秆还田结合适宜氮肥运筹促进小麦穗粒数和结实率提高,从而提高了小麦籽粒产量。因此,综合小麦产量、秸秆还田后土壤理化性状,小麦基肥-分蘖肥-穗肥施用比例50-30-20运筹方式下,配合实施与玉米秸秆直接还田,能有效改良土壤理化性质,提高小麦产量。

商品有机肥替代化肥对作物产量和土壤肥力的影响

【目的】通过连续3年定位监测华北平原冬小麦-夏玉米轮作区商品有机肥部分替代化肥施用后作物产量和土壤肥力的变化,探究商品有机肥替代化肥对作物产量及土壤肥力的影响,以期为该区域商品有机肥的科学施用提供理论依据。【方法】试验开始于2011年,于山东禹城设置3个不同施肥处理:不施肥对照(T1);单施化肥(T2);等养分条件下,有机肥部分替代化肥(T3)(氮、磷和钾替代比例分别为11.3%、13.7%和58.8%)。于2011—2014年连续3年进行田间取样,分析冬小麦-夏玉米轮作制度下,不同施肥处理对作物产量、产量构成以及土壤有机碳、全氮、速效磷、速效钾含量的影响。【结果】(1)商品有机肥部分替代化肥施用后,冬小麦和夏玉米3年平均产量分别为7 700和9 175 kg·hm^(^(-2)),与当地栽培条件下高产水平相当,但与单施化肥处理相比差异不显著。(2)与单施化肥相比,商品有机肥替代化肥处理对产量构成因素(有效穗数、穗粒数和千粒重)未表现出显著影响。(3)商品有机肥部分替代化肥施用3年后,与单施化肥相比,土壤有机碳增加了19.5%、土壤全氮提高了12.3%,显著高于单施化肥处理。【结论】商品有机肥部分替代化肥能保证华北平原小麦-玉米轮作体系的作物稳产、高产,并且能够培肥地力,有利于土壤可持续利用。

长期不同施肥措施对土壤和作物重金属累积的影响

分析测定黑土、潮土和红壤在20多年不同施肥措施(不施肥、单施化肥、化肥与有机肥配施)下土壤和作物中Cu、Zn、Cd的含量,结果表明:长期单施化肥对黑土、潮土、红壤Cu、Zn、Cd含量没有显著影响;在黑土和红壤上,有机肥与化肥配施与对照不施肥相比显著提高Cu、Zn和Cd含量;红壤上有机肥和化肥配施(NPKM和1.5NPKM)处理小麦籽粒和秸秆Cu、Zn、Cd含量显著高于单施化肥处理(NPK),而且化肥配施有机肥(NPKM)与单施化肥相比(NPK)显著提高玉米籽粒和秸秆Zn、Cd含量;在潮土上,NK处理显著提高小麦籽粒和秸秆中Zn含量;黑土上各处理玉米籽粒中Cd含量无显著差异,而化肥配施有机肥比单施化肥显著提高玉米籽粒Zn含量。根据测定数据估算,在目前施肥措施和作物种植体系下,黑土对Cu、Zn、Cd的最高承载年限分别为67年、118年、9年,潮土分别为1042年、2043年、631年,红壤分别为10年、46年、0.5年。假设土地承载年限为45年且有机肥施用量低于10 t·hm-2,黑土和潮土可接受有机肥中Cd的最高限量低于我国有机肥中的平均含量,说明实际生产中施用有机肥造成土壤Cd污染的风险较大。因此,有必要尽快制定有机肥中重金属的安全限量标准,以确保土壤和农产品安全。

不同有机肥与化肥配施对氮素利用率和土壤肥力的影响

【目的】不同类型畜禽粪便有机肥在成分和性质上存在明显差异,本文研究了华北地区主要有机肥与化肥以不同比例配施后,对作物氮素吸收利用及土壤养分的影响,以期为本地区有机肥的科学利用提供理论依据和数据支撑。【方法】在华北平原冬小麦–夏玉米种植区进行田间试验。以推荐养分施用量(每季作物N 225kg/hm^2)为基础,设置了1个常规单施化肥处理(CF),12个鸡粪、猪粪和牛粪氮分别与化肥氮配比处理(有机肥氮素占比25%、50%、75%、100%),化肥及3种有机肥的加倍单施处理,同时设1个不施肥处理为对照,共18个处理。分析了作物的氮素吸收量、氮素利用效率,测定了0-20、20-40 cm土层土壤氮、磷、钾含量。【结果】常规施肥量下,单施鸡粪、猪粪、牛粪处理的氮素收获指数(NHI)均与化肥处理相当,平均为79.06%;单施牛粪处理的氮素生理利用率(NPE)为64.42 kg/kg,显著高于化肥处理;而单施鸡粪、猪粪处理的NPE与化肥处理相当,平均为55.14 kg/kg。与常规施肥量相比,加倍施用鸡粪、猪粪和化肥处理的显著降低NHI值和NPE值,而加倍牛粪处理的NHI与NPE值没有降低。牛粪、鸡粪、猪粪与化肥配施的处理间NHI与NPE值均未表现出显著性差异,且与单施化肥的处理相当。常规施氮量下,单施猪粪、鸡粪处理的氮素偏生产力(PFP)和回收率(NRE)接近,均值为分别39.67 kg/kg和41.85%,达到了单施化肥处理的水平,而牛粪处理的氮素PFP以及NRE仅为29.08 kg/kg和15.6%,显著低于化肥、鸡粪和猪粪处理。与常规施氮量相比,加倍施用牛粪、鸡粪、猪粪和化肥处理的氮素的PFP值平均降低了49.1%,氮肥NRE值平均降低了23.2%。牛粪、鸡粪、猪粪与化肥各配施比例处理的氮素PFP和NRE值均达到了单施化肥的水平。与单施化肥相比,单施有机肥以及有机无机配施没有明显提高土壤全氮含量,但显著提高有效磷和速效钾含量,单施鸡粪、猪粪处理土壤表层有效磷含量分别是单施化肥处理的5.82和7.06倍。【结论】推荐施肥量下,鸡粪或猪粪单独施用或配施少量化肥氮,牛粪配施75%左右的化肥氮可实现与化肥相当的氮素利用效率,同时提升土壤肥力。在实际生产中应根据有机肥特性调节有机肥与化肥配施比例,实现有机肥的科学利用。

潮土区小麦玉米轮作周期内土壤钾素的动态研究 Ⅱ.施钾对作物产量及土壤钾素动态的影响

研究了豫北潮土区在小麦 玉米轮作周期内不同施钾水平上作物的产量效应与土壤钾素的动态变化。结果表明：供试土壤施钾后不仅提高耕层土壤速效钾含量，而且也很快向缓效钾方向转化，转化量随钾肥用量的提高而增大。整个轮作周期内土壤速效钾及缓效钾含量与施钾量之间呈显著正相关关系。转化为缓效钾的肥料钾比土壤原有缓效钾更易释放，有效性较高。施钾对小麦、玉米都有显著增产效果，以小麦、玉米２ 季各施钾素２００ ｋｇ／ｈｍ２ 左右为宜，不仅可获理想的作物产量，而且可有效地提高土壤钾素含量和供钾水平。