调酸培肥技术对井冈蜜柚果园土壤及果实产量和品质的影响

井冈蜜柚是江西省果业三大品牌之一,生产中不合理的肥料施用导致的土壤酸化是柚园土壤退化的重要表现之一,也是制约蜜柚果实产量和品质的关键因素。选取江西省吉安市6年树龄金沙柚,在2020-2022年开展田间定位试验,试验设置农民习惯施肥技术和调酸培肥技术(有机肥替代30%化肥+石灰+硅钙钾镁肥+绿肥周年间作)2个处理,研究调酸培肥技术对土壤及果实产量和品质的影响。结果表明,与农民习惯施肥技术相比,采用调酸培肥技术3年,土壤pH平均提高了0.93(P<0.05),土壤有机质含量平均提高了19.17%(P<0.05),土壤碱解氮、有效磷、速效钾、交换性镁、交换性钙含量显著增加,土壤质量指数显著提高了0.25(P<0.05),蜜柚叶片氮、钾、镁和钙含量均随之显著提高。同时,施用调酸培肥技术蜜柚产量显著提高了25.99%(P<0.05),果实维生素C含量和糖酸比分别提高了5.85%和23.60%(P<0.05),可滴定酸含量显著降低。此外,采用调酸培肥技术3年,产值平均增加了3.41万元·hm^(-2),经济效益平均增加了2.28万元·hm^(-2)。综上,调酸培肥技术能够降低红壤区蜜柚果园土壤酸度,提高土壤和叶片养分含量,改善树体营养,提升果实产量和品质,提高果园经济效益,是改善土壤质量、实现井冈蜜柚果园提质增效的有效措施。

红壤丘陵区稻田土壤剖面肥力特征及其与产量的关系

【目的】探究不同产量稻田土壤肥力的剖面特征,明确调控作物产量的关键环境因子,以提高低产田、稳定高产田的粮食产量,实现“藏粮于地”的国家战略目标。【方法】试验在江西进贤进行,稻田年产量>15000 kg/hm^(2)、12000~15000 kg/hm^(2)和<10000 kg/hm^(2)的地块分别代表高产、中产和低产土壤,选取高、中、低产量稻田样点各3个,采集耕作层、犁底层和潴育层土壤样品,测定耕作层厚度、容重、土壤紧实度、pH、阳离子交换量(CEC)、有机质含量、全量和有效氮磷钾含量、微生物生物量碳(MBC)和氮(MBN)等,并对土壤剖面性质和水稻产量进行线性相关分析和随机森林分析。【结果】1)高产田耕作层最厚,在16 cm左右,而低产田在13 cm左右,高产田耕作层土壤容重最小,为1.09 g/cm^(3),而低产田为1.21 g/cm^(3),高产田犁底层厚度和紧实度均最高,低产田最低。2)高、中、低产田土壤pH、碳氮磷养分含量和微生物生物量均表现为高产田>中产田>低产田,在土壤剖面上具有明显的“表聚”特征。高产田耕作层土壤有机质、全氮、有效氮、全磷和有效磷含量分别为38.82 g/kg、2.33 g/kg、198.54 mg/kg、0.81 g/kg和33.04 mg/kg,而低产田耕作层分别为29.75 g/kg、1.89 g/kg、158.71 mg/kg、0.62 g/kg和23.51 mg/kg。高产田耕作层土壤MBC和MBN含量分别为929.2、42.5 mg/kg,而低产田分别为533.6、30.8 mg/kg。3)在3个产量水平稻田土壤中钾素含量均随土层深度增加而增加,在低产田表现尤其明显,低产田耕作层全钾含量为8.12 g/kg,但母质层为10.77 g/kg。4)相关性分析和随机森林分析结果表明,水稻产量与耕作层土壤pH、有机质、全量和有效氮磷钾含量、微生物生物量碳氮以及微生物生物量碳氮比、耕作层厚度均呈显著正相关,这些变量可以解释水稻产量变化的53.7%,其中,微生物生物量碳、微生物生物量碳氮比和耕作层厚度是影响作物产量最重要的环境因素,其解释能力分别为9.2%、8.7%和7.9%。【结论】耕作层厚度和耕作层微生物生物量是调控水稻产量的关键环境因素。相比低产田,高中产田耕作层厚,耕作层土壤容重低、有机质含量高,供肥保肥能力强。因此,增加耕作层厚度和提高微生物生物量是改良中、低产田的关键。

壮秧影响不同节氮水平下早稻产量及氮肥吸收利用

【目的】培育壮秧和施用分蘖肥是促进水稻早发的重要措施,但增施分蘖肥易导致水稻无效分蘖增加和氮素流失。研究双季稻区早稻壮秧和分蘖肥节氮条件下产量形成和氮素吸收利用特性,以期为早稻节氮控污和丰产栽培提供科学依据。【方法】以超级杂交早稻‘淦鑫203’为材料,采用壮苗育秧(状秧)和普通育秧(普秧)两种方式培育秧苗。于2014-2015年进行大田试验,设置壮秧常规施氮(VS+100%N)、节氮10%(VS–10%N)、节氮20%(VS–20%N)、节氮30%(VS–30%N) 4个处理,以普秧常规施氮(NS+100%N)处理和不施氮空白(NS+0N)处理分别作对照,共6个处理。减施的氮肥均在分蘖肥中扣除,除不施氮对照外,各处理基肥氮(72 kg/hm^2)和穗肥氮(54 kg/hm^2)均保持不变。分析早稻拔节期、齐穗期和成熟期SPAD值、光合速率、硝酸还原酶活性和各器官氮素含量,并测定成熟期水稻产量及其构成,明确了植株总氮积累量、氮素转运量、氮表观转运率、氮素利用效率等。【结果】与NS+100%N处理相比,壮秧条件下分蘖肥节氮10%~30%对叶片SPAD值和光合速率无显著影响,但壮秧能促进分蘖发生和成穗,在生育中后期可逐渐弥补分蘖肥节氮对分蘖期干物质积累的不利影响,成熟期VS–10%N和VS–20%N处理干物质积累量较对照NS+100%N增加,产量分别增加了8.5%和1.5%;VS–30%N处理干物质积累量和产量则呈下降趋势。同时,壮秧有利于提高早稻叶片硝酸还原酶活性、各器官氮含量和氮积累量,与NS+100%N处理相比,VS+100%N处理成熟期氮素积累量显著增加了6.9%,VS–10%N和VS–20%N处理无显著变化,VS–30%N处理显著下降了9.7%。壮秧处理氮素回收率和氮素农学效率较NS+100%N处理分别显著提高了12.1%~22.4%和9.9%~24.7%(P <0.05)。【结论】双季稻区早稻壮秧可以促进分蘖早发,提高叶片的干物质生产能力和氮代谢性能,弥补分蘖肥减氮后对水稻前期生长的不利影响,提高后期的干物质生产量和氮运转量。通过培育壮秧,分蘖肥减施总施氮量的20%以内,早稻产量不会下降,可实现水稻的节氮、丰产和节本栽培,有利于提高氮素利用效率和减少氮素流失对环境的污染。

基于预设SPAD阈值的花生氮肥施用效果研究

为利用花生叶片SPAD值进行实时、无损诊断花生生长过程中的氮素丰缺,指导花生合理施用氮肥,试验通过设定花生出苗后30、45、60、75 d和90 d倒3叶的SPAD值,分别将SPAD值按各时间段在30～33、38～41、42～45、44～47和43～46每隔1个点值预设一种施氮方案,共3种方案(分别以SN-1、SN-2和SN-3表示),探究不同氮素管理方案对花生的自身固氮力、氮素利用效率和产量的影响效果。研究结果显示,3种方案中,SN-3阈值设定过高,不利于花生的生长,SN-1和SN-2的阈值设定方案较合理,均可促进花生根瘤生长,提高氮素利用效率和产量。其中,SN-1的阈值设定最佳,与常规施肥比较,SN-1的花生单株根瘤量和单个根瘤重分别增加17.65%和4.35%,氮素利用效率和氮素农学利用效率分别提高19.36和3.99个百分点,花生产量增加12.95%。因此,SN-1方案的SPAD预设值可以作为花生栽培过程中各生育时段的氮素丰缺阈值。

Root characteristics and yield of rice as affected by the cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application

To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems,we investigated the effects of a cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application(SDN)on the morphological and physiological characteristics of double cropping rice.Our results indicated that the effects of SDN on the morphological characteristics of the single plant roots of double cropping rice were not significant,but the morphological characteristics of the population roots were largely different.Specifically,SDN significantly increased the morphological indexes of the root population such as root fresh weight,root volume,root number,root length and root dry weight.The effects of SDN on the total root absorption areas and root active absorption areas of the single plants were non-significant,but it dramatically enhanced the total root absorption areas and root active absorption areas of the plant population during the tillering,heading and mature stages.In addition,SDN significantly increased the root bleeding intensity and elevated the soluble sugar and free amino acid contents of root bleeding sap.Compared to the traditional cultivation pattern(CK),SDN significantly increased root bleeding intensity at the heading stage by 4.37 and 8.90% for early and late rice,respectively.Meanwhile,SDN profoundly enhanced the soluble sugar contents of root bleeding sap by 12.85 and 10.41% for early and late rice,respectively.In addition,SDN also significantly enhanced free amino acid content of root bleeding sap by 43.25% for early rice and by 37.50% for late rice systems compared to CK.Furthermore,SDN increased the actual yield of double cropping rice mainly due to the higher effective panicle number and the larger seedsetting rate.The actual yields of early rice under SDN were higher than CK by 9.37 and 5.98% in 2016 and 2017,and the actual yields of late rice under SDN were higher than CK by 0.20 and 1.41% in 2016 and 2017,respectively.Correlation analysis indicated that the significant positive correlations were observed between the majority of the root indexes and the actual yield across the four different growth stages.