在大田条件下,研究了水稻秸秆还田和施氮量对晚播小麦产量、养分积累、秸秆养分释放及养分平衡的影响.结果表明: 水稻秸秆还田并配施适当的施氮量有利于提高晚播小麦籽粒产量.晚播小麦全生育期的干物质、氮、磷、钾积累量均随施氮量增加而显著增加,相同施氮量(270 kg N·hm-2)下,秸秆还田处理的干物质、磷、钾积累高于不还田处理,氮积累则呈相反趋势.随着施氮量增加,秸秆腐解和养分释放率增加,且拔节后秸秆养分释放量占总释放量的比例降低;随生育进程的推进,秸秆的干物质、磷、钾释放量呈倒“N”型变化趋势,而氮释放量则呈“V”型变化趋势.计算养分表观平衡结果表明,秸秆还田并增加施氮量,养分总盈余量显著升高;在获得较高产量的施氮条件下,氮、钾素显著盈余,磷素投入较为合理.晚播小麦实行秸秆还田后,可适当增加氮肥用量至257 kg·hm-2,并减少钾肥投入.
Field experiments were conducted to study the effects of nitrogen application rates and straw returning on grain yield, nutrient accumulation, nutrient release from straw and nutrient balance in late sowing wheat. The results showed that straw returning together with appropriate application of nitrogen fertilizer improved the grain yield. Dry matter, nitrogen, phosphorus and potassium accumulation increased significantly as the nitrogen application rate increased. At the same nitrogen application rate (270 kg N·hm-2), the dry matter, phosphorus and potassium accumulation of the treatment with straw returning were higher than that without straw returning, but the nitrogen accumulation was lower. Higherrate nitrogen application promoted straw decomposition and nutrient release, and decreased the proportion of the nutrient released from straw after jointing. The dry matter, phosphorus and potassium release from straw showed a reverse ‘N’ type change with the wheat growing, while nitrogen release showed a ‘V’ type change. The nutrient surplus increased significantly with the nitrogen application rate. At the nitrogen application rate for the highest grain yield, nitrogen and potassium were surplus significantly, and phosphorus input could keep balance. It could be concluded that as to late sowing wheat with straw returning, applying nitrogen at 257 kg·hm-2 and reducing potassium fertilizer application could improve grain yield and reduce nutrients loss.
全 文 :施氮和秸秆还田对晚播小麦养分平衡和产量的影响∗
张 姗1,2 石祖梁1∗∗ 杨四军1 顾克军1 戴廷波2 王 飞3 李 想3 孙仁华3
( 1江苏省农业科学院农业资源与环境研究所, 南京 210014; 2南京农业大学农学院, 南京 210095; 3农业部农业生态与资源保
护总站, 北京 100125)
摘 要 在大田条件下,研究了水稻秸秆还田和施氮量对晚播小麦产量、养分积累、秸秆养分
释放及养分平衡的影响.结果表明: 水稻秸秆还田并配施适当的施氮量有利于提高晚播小麦
籽粒产量.晚播小麦全生育期的干物质、氮、磷、钾积累量均随施氮量增加而显著增加,相同施
氮量(270 kg N·hm-2)下,秸秆还田处理的干物质、磷、钾积累高于不还田处理,氮积累则呈
相反趋势.随着施氮量增加,秸秆腐解和养分释放率增加,且拔节后秸秆养分释放量占总释放
量的比例降低;随生育进程的推进,秸秆的干物质、磷、钾释放量呈倒“N”型变化趋势,而氮释
放量则呈“V”型变化趋势.计算养分表观平衡结果表明,秸秆还田并增加施氮量,养分总盈余
量显著升高;在获得较高产量的施氮条件下,氮、钾素显著盈余,磷素投入较为合理.晚播小麦
实行秸秆还田后,可适当增加氮肥用量至 257 kg·hm-2,并减少钾肥投入.
关键词 施氮量; 秸秆还田; 晚播小麦; 养分平衡
文章编号 1001-9332(2015)09-2714-07 中图分类号 S512.1 文献标识码 A
Effects of nitrogen application rates and straw returning on nutrient balance and grain yield
of late sowing wheat in rice⁃wheat rotation. ZHANG Shan1,2, SHI Zu⁃liang1, YANG Si⁃jun1,
GU Ke⁃jun1, DAI Ting⁃bo2, WANG Fei3, LI Xiang3, SUN Ren⁃hua ( 1Institute of Agriculture Re⁃
sources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; 2Col⁃
lege of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; 3Ministry of Agricul⁃
ture Rural Energy and Environment Agency, Beijing 100125, China) . ⁃Chin. J. Appl. Ecol., 2015,
26(9): 2714-2720.
Abstract: Field experiments were conducted to study the effects of nitrogen application rates and
straw returning on grain yield, nutrient accumulation, nutrient release from straw and nutrient ba⁃
lance in late sowing wheat. The results showed that straw returning together with appropriate appli⁃
cation of nitrogen fertilizer improved the grain yield. Dry matter, nitrogen, phosphorus and potas⁃
sium accumulation increased significantly as the nitrogen application rate increased. At the same ni⁃
trogen application rate (270 kg N·hm-2), the dry matter, phosphorus and potassium accumulation
of the treatment with straw returning were higher than that without straw returning, but the nitrogen
accumulation was lower. Higher⁃rate nitrogen application promoted straw decomposition and nutrient
release, and decreased the proportion of the nutrient released from straw after jointing. The dry mat⁃
ter, phosphorus and potassium release from straw showed a reverse ‘N’ type change with the wheat
growing, while nitrogen release showed a ‘V’ type change. The nutrient surplus increased signifi⁃
cantly with the nitrogen application rate. At the nitrogen application rate for the highest grain yield,
nitrogen and potassium were surplus significantly, and phosphorus input could keep balance. It
could be concluded that as to late sowing wheat with straw returning, applying nitrogen at 257
kg·hm-2 and reducing potassium fertilizer application could improve grain yield and reduce nutri⁃
ents loss.
Key words: nitrogen application rate; straw returning; late sowing winter wheat; nutrient balance.
∗国家自然科学基金项目(31401335)、江苏省农业科技自主创新资金项目[CX(12)1002]和国家科技支撑计划项目(2013BAD07B09)资助.
∗∗通讯作者. E⁃mail: shizuliang1985@ 163.com
2014⁃11⁃25收稿,2015⁃05⁃06接受.
应 用 生 态 学 报 2015年 9月 第 26卷 第 9期
Chinese Journal of Applied Ecology, Sep. 2015, 26(9): 2714-2720
稻麦轮作是我国重要的茬口类型,全国稻茬麦
的种植面积约为 500万 hm2[1-2],其中江苏省稻茬麦
面积约占全国的 1 / 3.近年来, 随着江苏水稻种植方
式的重大改变(直播稻和机插秧)和中熟中粳水稻
品种的推广,水稻收获期大幅延迟,使小麦明显错过
播种适期,晚播小麦的面积逐渐扩大[3] .小麦晚播
后,由于温度降低,小麦冬前出苗慢、出苗不匀、苗情
素质较差、分蘖下降,个体发育和生物量均受到限
制,极易造成大面积减产[4-5] .长期以来,肥料施用一
直是小麦增产的重要应用手段,前人针对小麦高产、
高效、优质、生态安全的肥料应用技术进行了大量研
究,并提出依据养分的盈亏状况进行肥料管理,以提
高肥效、降低环境污染[6-10],但对稻茬晚播小麦养分
平衡状况报道较少.同时,由于农村生产、生活方式
的转变和能源消费结构的改善,秸秆禁烧成为全社
会高度关注的热点,水稻秸秆还田成为稻茬麦生产
不容回避的问题.秸秆含有丰富的有机碳、氮、磷、钾
和其他营养元素.有研究表明,秸秆还田可以有效地
改善土壤理化性状,提高土壤酶活性,使土壤养分向
更易于作物吸收的形态转化,对作物产量和品质形
成产生良好的促进作用[11-13];也有研究表明,秸秆
还田极易造成土壤透风失墒,降低作物的播种质量,
而且还田初期秸秆分解会出现与苗争氮的现象,对
作物苗期生长不利[14-15] .因此,进一步明确秸秆还
田后植株养分需求和秸秆养分释放规律,对于晚播
小麦肥料施用具有重要意义.为此,本文研究了秸秆
还田和施氮量对小麦产量、养分吸收积累、秸秆腐解
与养分释放,以及养分平衡状况的影响,以期为高
产、高效、生态安全的稻茬小麦生产提供科学依据和
技术指导.
1 材料与方法
1 1 试验设计
大田试验于 2012—2013 年在江苏省农业科学
院徐州花碱土实验站进行.试验地 0 ~ 20 cm 土层土
壤含有机质 24.56 g·kg-1、矿质氮 11.35 mg·kg-1、
全氮 1.04 g·kg-1、速效磷 8.02 mg·kg-1、有效钾
142.71 mg·kg-1 .供试小麦品种为‘淮麦 20’,前茬
作物为水稻.水稻秸秆还田量约为 7400 kg·hm-2,
秸秆含氮量为 1. 0%,含磷量为 0 1%,含钾量为
0 9%.水稻收获时,采用带有扩散匀铺装置的半喂
入收割机进行收割及秸秆均匀抛撒.
当地小麦适播期为 10 月 15 日左右,本试验小
麦播种期为 11 月 4 日,以形成晚播小麦.秸秆全量
还田处理使用反转灭茬机进行旋耕还田,旋耕深度
为 15 cm 左右,小麦全生育期设 0、90、180、270 和
360 kg·hm-2 5个施氮量处理,分别用 N0、N90、N180、
N270、N360表示,基追比例为 5 ∶ 5,追肥于拔节期施
入.根据前期研究结果,在施氮量 270 kg·hm-2时能
够获得较高的稻茬麦产量[16-17],因此在 N270处理下
设秸秆不还田处理作为对照(CK).每处理施磷肥
(P 2O5)100 kg·hm
-2,钾肥(K2 O) 105 kg·hm
-2,
磷、钾肥与基施氮肥作为底肥于播前一次性施入.小
区面积 20 m2,随机区组设计,3 次重复,基本苗 375
万株·hm-2 .由于网袋法使秸秆无法完全接触土壤,
可能会对秸秆腐解的测定结果造成误差,因此在每
小区垂直砸入 4 个长 25 cm、宽 25 cm、高 15 cm 的
无底镀锌铁框设置微区,以模拟田间实际情况;依据
大田试验条件换算秸秆还田量、施氮量和播种量,将
秸秆与 0~15 cm土壤充分混匀[17],其他田间管理同
一般大田.
1 2 田间取样与测定方法
分别于越冬期(播种后 82 d)、拔节期(播种后
147 d)、开花期(播种后 185 d)和成熟期(播种后
220 d)取地上部植物样品 25 株,按茎、叶、籽粒、颖
壳分离,同时将框内 0 ~ 15 cm 土壤完全取出,先将
可识别的未腐秸秆挑出,不可识别的未腐秸秆用水
浸泡,快速收集飘浮起来的残留物,合并归为未腐解
残留秸秆,冲洗干净.植株和秸秆鲜样在 105 ℃下杀
青 30 min 后,70 ℃烘干至恒量,称量,计算干物质
量.样品粉碎后用 H2SO4⁃H2O2消煮,采用半微量凯
氏定氮法测定全氮含量,钼锑钪比色法测定全磷含
量,火焰光度法测定全钾含量.
于成熟期每小区取 2 m2小麦脱粒,晒干后测定
实际产量,同时调查产量构成因素.
1 3 计算方法
作物养分(氮 /磷 /钾)积累量(kg·hm-2) = 植
株干物质积累量×植株养分(氮 /磷 /钾)含量
起始秸秆养分积累量(kg·hm-2)=还田秸秆量
×秸秆养分含量
未腐解秸秆养分积累量(kg·hm-2)=未腐解残
留秸秆量×未腐解残留秸秆养分含量
秸秆养分释放率=(起始秸秆养分积累量-未腐
解秸秆养分积累量) /起始秸秆养分积累量×100%
养分平衡计算采取表观平衡法,即用养分投入
量与养分输出量的差值来表示,其中养分投入量为
化肥的投入和秸秆养分的释放量,不考虑降水、灌溉
等带入的养分;养分输出量包括小麦成熟后秸秆和
51729期 张 姗等: 施氮和秸秆还田对晚播小麦养分平衡和产量的影响
籽粒中的养分积累量[18-19] .
1 4 数据处理
采用 Excel 2010 和 SPSS 软件分别对数据进行
作图和统计分析.数据的显著性分析和多重比较采
用最小显著差异法( LSD 法),显著性水平设定为
α= 0 05.图表中数据为平均值±标准差.
2 结果与分析
2 1 秸秆还田和施氮量对晚播小麦产量的影响
表 1显示,施氮能显著增加晚播小麦籽粒产量,
N90、N180、N270、N360处理分别比 N0处理产量增加
40 6%、68.5%、73.6% 和 61.6%.通过多项式拟合:
y = -0.0373x2+19.175x+3284.5, R2 = 0.99,在施氮
量达到 257. 0 kg·hm-2时,稻茬晚播小麦可获得
5748.9 kg·hm-2的最高产量,施氮量继续升高则产
量下降.分析产量构成因素发现,随施氮量增加,晚
播小麦群体有效穗数和穗粒数增加,但千粒重呈下
降趋势.相同施氮量(N270)条件下,秸秆还田处理较
不还田处理增产 5.9%,产量构成因素显示主要是由
于穗粒数显著增加.
表 1 秸秆还田和施氮量对晚播小麦产量及其构成因素的
影响
Table 1 Effects of straw returning and nitrogen applica⁃
tion rate on grain yield and yield components of late sowing
wheat
处理
Treat⁃
ment
有效穗数
Effective panicle
(×104·hm-2)
穗粒数
Spikelet per
panicle
千粒重
1000⁃grain
mass (g)
实产
Yield
(kg·hm-2)
N0 427±47c 24.52±0.88d 34.86±0.32a 3306.63±189.56d
N90 481±7b 30.77±0.75c 32.60±0.22c 4649.20±61.21c
N180 494±18ab 33.00±1.00b 32.23±0.26c 5570.20±32.22ab
N270 524±19ab 34.67±1.04a 31.83±0.92c 5741.65±201.01a
N360 513±8ab 35.33±0.31a 30.74±0.29d 5342.69±85.30b
CK 534±5a 30.27±0.20c 33.85±0.60b 5423.85±240.59b
N0、N90、N180、N270、N360分别表示在秸秆还田条件下施氮量为 0、90、
180、270、360 kg· hm-2; CK 表示秸秆不还田下施氮量为 270
kg·hm-2 N0, N90, N180, N270, N360meant nitrogen application rate was
0, 90, 180, 270, 360 kg·hm-2 with straw returning, respectively; CK
meant nitrogen application rate was 270 kg·hm-2 without straw retur⁃
ning. 同列不同小写字母表示处理间差异显著(P< 0. 05) Different
small letters in the same column meant significant difference among treat⁃
ments at 0.05 level. 下同 The same below.
2 2 秸秆还田和施氮量对晚播小麦养分积累的
影响
施氮量和秸秆还田对晚播小麦干物质、氮
素、磷素和钾素的积累均有显著影响(表2) .不同生
表 2 秸秆还田和施氮量对晚播小麦养分积累的影响
Table 2 Effects of straw returning and nitrogen application rate on nutrient accumulation of late sowing wheat (kg·hm-2)
养分
Nutrient
处理
Treatment
播种-越冬
Sowing to
overwintering
越冬-拔节
Overwintering to
jointing
拔节-开花
Jointing to
anthesis
开花-成熟
Anthesis to
maturity
播种-成熟
Sowing to
maturity
干物质 N0 304±17d 969±14d 5402±189b 1688±58b 8363±216d
Dry N90 319±7c 1026±23c 6142±95ab 1718±202b 9205±92c
matter N180 315±21cd 1047±8bc 6304±402ab 1816±274ab 9482±115c
N270 334±20b 1079±13ab 6467±627ab 2591±448ab 10470±187a
N360 343±16ab 1076±28ab 6530±187a 2677±43a 10625±132a
CK 350±10a 1108±16a 6279±484ab 2219±550ab 9956±41b
N0 8.13±0.38b 22.08±0.13b 47.62±0.14d 9.85±1.60c 87.68±2.26e
N N90 8.85±0.03a 25.71±4.71b 90.68±6.37c 15.08±3.69bc 140.83±7.41d
N180 8.61±0.00a 32.72±2.91a 110.54±1.55b 17.02±4.64bc 168.89±9.10c
N270 8.70±0.43a 34.94±0.56a 126.29±4.56a 20.45±0.18bc 190.38±5.37b
N360 8.90±0.04a 32.72±1.20a 124.69±6.38a 35.22±6.46a 201.52±14.00a
CK 9.32±1.47a 34.97±2.05a 124.39±4.61a 25.33±2.84ab 194.01±5.29ab
P N0 4.78±0.32a 11.77±1.09ab 51.89±2.50b 12.78±2.04c 81.22±5.96c
N90 4.70±1.27a 11.17±0.65b 52.65±0.94ab 15.43±1.37bc 83.95±2.36c
N180 4.05±0.45ab 12.76±0.02ab 58.17±1.72a 19.35±6.19bc 94.32±8.31b
N270 3.69±0.66ab 14.61±2.82a 52.65±0.02ab 24.24±3.01b 95.19±0.44b
N360 4.26±0.05ab 11.65±2.31b 53.17±0.23ab 39.83±0.60a 108.92±1.98a
CK 3.47±0.09b 13.30±1.91ab 44.01±3.12d 23.36±1.87b 84.15±3.24c
K N0 3.65±0.76a 22.74±0.91a 53.89±3.73e -29.09±1.95c 51.20±7.36e
N90 3.87±0.39a 24.25±2.66a 65.85±1.78c -30.96±1.06c 63.00±3.77d
N180 3.50±0.34a 23.78±0.17a 74.93±2.86b -28.55±0.22c 73.68±3.25c
N270 3.84±0.29a 25.31±2.06a 76.88±4.10ab -23.74±5.81bc 82.28±0.64b
N360 3.27±1.11a 23.19±0.25a 78.91±2.53a -16.00±2.33a 89.37±1.56a
CK 3.73±0.14a 25.28±2.45a 62.56±2.51d -20.11±1.66ab 71.46±6.77c
6172 应 用 生 态 学 报 26卷
育阶段晚播小麦干物质积累均随施氮量增加而显著
增加;在 N270处理下,秸秆不还田处理在播种-越冬
和越冬-拔节阶段的干物质积累高于还田处理,而
拔节-开花和开花-成熟阶段相反;不同处理群体全
生育期干物质积累量呈“S”型曲线,播种-越冬、越
冬-拔节、拔节-开花、开花-成熟阶段的干物质积累
占全生育期比例分别为 3. 2% ~ 3. 6%、 10. 1% ~
11 6%、61 5%~66.7%、18.7% ~25 2%.全生育期氮
素积累随施氮量增加而显著增加,N270处理下秸秆
不还田处理高于还田处理,但二者无显著差异;各生
育阶段氮素积累比例分别为 4.4% ~ 9.3%、16.2% ~
25.2%、54.3% ~ 66.3%、10.1% ~ 17.5%.全生育期磷
素和钾素积累均随施氮量增加而显著增加,N270处
理下的秸秆不还田处理则显著低于秸秆还田处理;
磷素在各生育阶段积累比例分别为 3.9% ~ 5.9%、
10.7%~ 15 8%、48 8% ~ 63.9%、15.7% ~ 36.6%,而钾
素各阶段的积累比例分别为 3.7% ~ 7.1%、26.0% ~
44 4%、87 6%~105 3%、-56.8%~ -17. 9%,表明钾
素在小麦花后出现明显的“外排”现象,秸秆不还田
和增加施氮量可以降低钾素外排量.
2 3 施氮量对水稻秸秆腐解的影响
水稻秸秆腐解率及氮、磷、钾的释放率均随施氮
量的增加而显著增加,不同处理秸秆干物质腐解率
为 54.8%~ 64.9%,秸秆不同养分释放率表现为钾
(96.3%~98.2%)>磷(69.1% ~84.3%)>氮(52.9% ~
64.8%)(表 3).随生育进程推进,秸秆养分释放差异
显著,且随施氮量增加,拔节后秸秆养分释放量占总
释放量的比例呈降低趋势.不同生育阶段秸秆腐解
量、磷和钾释放量均呈倒“N”型的变化趋势,秸秆腐
解表现为拔节-开花>播种-越冬>开花-成熟>越冬-
拔节;磷和钾释放则表现为播种-越冬>拔节-开花>
越冬-拔节>开花-成熟,其中 90%的秸秆钾素在播
种至越冬期释放出来;秸秆氮释放量呈“V”型变化
趋势,表现为播种-越冬>开花-成熟>拔节-开花>
越冬-拔节.
2 4 秸秆还田和施氮量对晚播小麦养分平衡的
影响
通过肥料投入、秸秆养分释放与植株养分积累
的差值计算了晚播小麦养分的表观平衡,结果表明,
秸秆还田和增加施氮量显著提高了晚播小麦的养分
盈余量,但不同营养元素的表现不同(表 4).氮素盈
余随施氮量增加和秸秆还田显著增加,N0和 N90处
理出现明显的表观亏缺;磷素盈余量随施氮量增加
和秸秆还田显著降低,在 N360处理下出现表观亏缺;
钾素盈余量随施氮量增加而显著降低,秸秆还田则
显著增加了钾素盈余.通过多项式拟合,在本试验条
表 3 施氮量对水稻秸秆养分释放的影响
Table 3 Effects of nitrogen application rate on nutrient release of rice straw
指标
Trait
处理
Treatment
总释放率
Total release
ratio
(%)
占总释放量比例 Percentage of total release amount (%)
播种-越冬
Sowing to
overwintering
越冬-拔节
Overwintering
to jointing
拔节-开花
Jointing
to anthesis
开花-成熟
Anthesis to
maturity
干物质 N0 54.8±3.7c 33.5±0.5b 4.1±0.3a 45.2±1.2a 17.3±1.4a
Dry N90 55.7±1.8c 33.3±1.0b 4.8±2.3a 44.6±0.5ab 17.3±2.8a
matter N180 61.4±2.5b 33.8±0.7b 5.5±0.4a 42.0±1.2bc 18.8±2.3a
N270 62.6±2.2b 36.4±0.7a 5.5±0.6a 40.4±2.0c 17.7±0.8a
N360 64.9±2.4a 36.8±0.7a 6.0±1.3a 39.8±1.7c 17.4±0.2a
N N0 52.9±0.1c 36.0±0.5b 10.9±2.5a 25.2±1.0a 28.3±2.0a
N90 57.1±1.5bc 36.6±0.1ab 11.0±1.9a 24.3±2.2a 28.1±0.4a
N180 60.0±5.0ab 36.8±0.3a 11.1±1.2a 24.1±1.6a 28.0±0.7a
N270 60.8±2.3ab 36.8±0.6a 11.3±0.5a 23.9±0.9a 27.9±0.9a
N360 64.8±0.3a 37.1±0.5a 11.3±0.9a 23.7±1.5a 27.7±2.9a
P N0 69.1±2.4c 35.0±0.2c 21.3±0.4a 38.2±1.0a 5.5±0.7a
N90 74.8±0.2b 37.6±1.0b 20.2±0.3a 36.7±0.4ab 5.5±1.1a
N180 77.1±1.5b 39.4±0.4ab 19.6±0.1ab 35.5±0.5b 5.4±0.2a
N270 78.6±1.6b 39.7±0.6ab 19.9±0.3a 35.0±2.0b 5.3±1.7a
N360 84.3±0.7a 41.3±1.5a 18.2±0.7b 35.2±0.7b 5.3±0.1a
K N0 96.3±0.1d 90.8±0.9a 2.8±0.1a 6.3±0.7a 0.2±0.1b
N90 97.2±0.1c 90.3±0.3a 2.9±0.3a 6.6±0.1a 0.3±0.0b
N180 97.8±0.2b 89.8±0.3a 2.8±0.3a 7.0±0.8a 0.4±0.2a
N270 98.1±0.1ab 89.9±0.9a 2.8±0.1a 6.9±0.8a 0.4±0.1a
N360 98.2±0.3a 89.9±0.0a 2.9±0.4a 6.9±0.3a 0.4±0.0a
71729期 张 姗等: 施氮和秸秆还田对晚播小麦养分平衡和产量的影响
表 4 秸秆还田和施氮量对晚播小麦养分平衡的影响
Table 4 Effects of straw returning and nitrogen application rate on nutrient balance of late sowing winter wheat (kg·
hm-2)
处理
Treatment
N P K 合计
Total
N0 -47.69±2.31f 23.99±6.14a 121.11±7.41a 97.40±15.86e
N90 -7.66±8.57e 21.69±2.34ab 109.98±3.83b 124.02±14.74d
N180 56.42±12.86d 11.49±8.42c 99.70±3.39c 167.61±24.67c
N270 125.56±7.14b 10.74±0.52c 91.31±0.59d 227.60±8.29b
N360 207.44±14.25a -2.56±2.04d 84.29±1.76e 289.18±18.05a
CK 75.99±5.29c 15.85±3.25bc 33.53±6.77f 125.38±15.30d
件下,氮(y= 8×10-4x2+0.4332x-49.202,R2 = 0.99)、
磷(y= -2×10-5 x2 -0.0525x+24.526,R2 = 0.94)、钾
(y= 9×10-5x2-0.1347x+121.18,R2 = 0.99)在获得最
高产量的施氮量(257.0 kg·hm-2)条件下将分别盈
余 115.0、9.7、92.5 kg·hm-2 .
3 讨 论
秸秆还田主要通过两种途径影响作物的生长发
育:一是通过自身分解释放的营养元素、化学物质等
直接影响作物生长;二是通过影响作物生长的环境
因子间接影响作物的生长[20] .因此,秸秆还田后冬
小麦产量有增有减[12,21-22] .秸秆还田对产量的正向
效应可能源于秸秆还田减缓了旗叶衰老、延长光合
时间和增强光合能力,提高了冬小麦生物量及花后
干物质积累量[23] .本研究表明,相同施氮量(N270)
下,秸秆还田处理在拔节-开花和开花-成熟阶段干
物质积累高于不还田处理,从而为增产奠定了基础.
这与杨佳凤等[24]的研究结论一致.陈金等[25]研究表
明,秸秆还田较不还田处理显著降低了群体穗数,但
提高了籽粒千粒重,可增产 6.9% ~ 8.0%.而本研究
表明,秸秆还田较不还田处理增产 5.9%,主要是源
于穗粒数的显著增加.这可能与秸秆还田提高了植
株的结实率有关[14] .秸秆还田造成减产的主要原因
除耕作方式外[20],还与化学氮肥的配比不当,导致
养分失衡有关[7] .合理施用氮肥是小麦高产栽培的
一个重要措施.秸秆还田后,为防止前期秸秆分解与
微生物争氮,生产上通常靠增加施氮量来缓解对作
物早期生长的负面影响,但氮肥配施量各不相同.前
人研究发现,秸秆还田配施纯氮 165 kg·hm-2时冬
小麦产量降低,而秸秆还田配施纯氮 225 kg·hm-2
则显著提高冬小麦产量[25] .本研究在稻草全量还田
7400 kg·hm-2的条件下,施氮量与晚播小麦产量呈
二次抛物线关系,在施氮量达到 257 kg·hm-2时,可
获得稻茬晚播小麦最高产量.
秸秆含有丰富的碳、氮、磷、钾以及中微量元素,
研究秸秆的腐解规律及其养分释放特征,并将其运
用到作物的施肥管理,对减少化肥用量和培肥土壤
具有现实意义.本研究表明,晚播小麦全生育期,水
稻秸秆中 96. 3% ~ 98. 2%钾、 69. 1% ~ 84. 3%磷、
52 9%~64.8%氮和 54.8% ~64.9%干物质被释放出
来,养分释放率表现为钾>磷>氮,其原因是秸秆中
钾主要以离子态存在,容易被水溶解出来[26-27];磷
60 0%以离子态存在,另一部分参与细胞壁的构成,
而碳、氮主要以较难腐解的有机态存在[28] .秸秆在
土壤中的分解和养分的释放与碳氮比、水分和温度
等密切相关[17],因此不同生育时期秸秆的养分释放
量有较大差异.本研究表明,不同生育阶段秸秆养分
释放基本呈现倒“N”型的变化趋势,可能与不同生
育阶段的温度影响微生物分解秸秆有关.适当增加
施氮量、降低碳氮比,能促进秸秆分解,并较多地释
放养分供给晚播小麦的生长.
农田养分平衡状况一方面决定着土壤肥力的发
展方向和施肥效果,另一方面养分的去向直接关系
着大气、水体的污染.目前,农田养分平衡通常是以
养分的总输入量与总输出量之差来表示养分的盈余
量,其盈余程度越大,对环境的污染风险就越大[6] .
本文采用肥料投入量、秸秆养分释放量和作物带走
的养分量 3 项指标来反映农田养分的一般平衡状
况,结果表明,随施氮量增加,氮素盈余显著增加,而
磷、钾盈余显著降低,表明增加施氮量有利于促进晚
播小麦的生长发育,进而促进植株对磷、钾的吸收积
累[29] .有研究认为,农田氮素平衡盈余超过 20.0%
时,可能引起对环境的潜在威胁[18,30] .本文通过计算
分析表明,在获得最高产量的施氮量时,氮、磷、钾将
分别盈余 115.0、9.7、92.5 kg·hm-2,磷素基本处于
平衡状态,氮、钾盈余量则显著偏高.相同施氮量下
(270 kg N·hm-2)秸秆还田较不还田处理显著增加
了氮、钾盈余量.因此,在小麦生产实际中,实行秸秆
8172 应 用 生 态 学 报 26卷
还田后应该对施肥方案进行修正.何虎等[14]研究表
明,在不增加氮肥总用量的前提下,秸秆全量还田前
期适当增大氮肥的施用比例,能够降低土壤碳氮比,
促进秸秆的矿化分解,防止微生物争氮带来的不利
影响.王志勇等[19]根据稻草钾素释放量高及其先快
后慢的特点,提出应适当降低钾素用量及其基肥比
例,适时追肥以维持土壤钾素平衡.而关于稻茬晚播
小麦秸秆还田后氮、钾肥的具体施用量和基追比例,
还需要结合大田试验进行深入研究.
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rotation models in field of Yunnan. Southwest China
Journal of Agricultural Sciences (西南农业学报),
2011, 22(3): 594-597 (in Chinese)
作者简介 张 姗,女,1990年生,硕士研究生. 主要从事小
麦生理生态研究. E⁃mail: 1558552873@ qq.com
责任编辑 孙 菊
0272 应 用 生 态 学 报 26卷