0 引言
【研究意义】农田生态系统的高产、稳产、高效、环境友好是国家粮食安全与可持续发展的关键。但在农业生产活动中,肥料施用仍存在许多不合理现象,造成作物产量稳定性差、肥料利用率低、资源浪费、养分流失和面源污染等一系列问题。因此,探讨田块尺度上作物产量、肥料利用及环境效应对合理施肥具有重要意义。【前人研究进展】在作物产量效应方面,冀建华等[1]采用AMMI模型分析25年定位施肥,发现均衡施化肥有效提高双季稻产量及产量的稳定性。而32年连续不施肥,小麦产量稳定性差[2]。门明新等[3]采用多种稳定性指数方法分析7年定位试验,发现小麦和玉米产量效应与施肥量有明显相关性,但产量稳定性与施肥量无明显关系,与氮、磷、钾肥配比明显相关。在地力贡献率、肥料贡献率及肥料农学利用率方面,门明新等[3]基于7年定位试验,发现不施氮肥,土壤氮自然供给力第1年降到59%,第2年为43%,此后稳定在40%左右。不施磷肥,土壤磷自然供给力第1年降至72%,第3年为55%,之后保持在55%左右。不施钾肥,土壤钾自然供给力第1年降为93%,第3年76%,之后基本不变。朱洪勋等[4]研究发现,黄潮土地力贡献率由1981年试验初的76.2%降至1995年的34.4%。王定勇等[5]根据定位试验,得出紫色土冬小麦地力贡献率在46.2%—55.2%。贡付飞等[6]根据基础地力产量模拟值与相应施肥实测产量模拟值的比值,计算出潮土冬小麦种植18年后NPK处理的地力贡献率为42.5%。在养分径流流失方面,大部分研究结果认为,施肥提高径流液氮磷浓度,但氮磷流失负荷因不同的土壤类型、作物类型、气候而异[7,8,9]。【本研究切入点】甘蔗是中国重要的糖料作物,其面积占全国常年糖料作物面积的85%以上[10]。广西水热条件丰富,是中国第一大甘蔗种植省区,无论是甘蔗栽培面积还是蔗糖产量占全国的比例均超过60%。但受地形条件的制约,70%以上的甘蔗种植在坡耕地[11]。甘蔗施肥量农户间差异很大,平均纯氮投入量370.5 kg?hm-2,其中,小于300 kg?hm-2的占37%,300—450 kg?hm-2的占40%,大于450 kg?hm-2的占23%。平均磷肥（P2O5）投入量166.5 kg?hm-2,小于150 kg?hm-2的占58%,150—225 kg?hm-2的占27%,大于225 kg?hm-2的占15%[12]。根据谭宏伟等[13]推荐的甘蔗施肥量,过量施入氮磷肥普遍存在。然而,过量施氮磷下引起的甘蔗产量、肥料农学利用率及环境的长期综合效应不清楚。【拟解决的关键问题】通过对甘蔗不同施肥方式进行8年监测,从产量、肥料贡献率、农学利用率及地表径流氮磷养分流失系统分析在分别过量施入氮、磷肥用量的前提下,南方赤红壤区甘蔗产量的稳定性及环境效应,进而明确推荐施肥下南方赤红壤区农田生态系统质量的优劣,为田块尺度上改进甘蔗-土壤系统内的养分调控,减少因过量施肥造成的养分资源浪费以及防治面源污染,促进蔗糖业持续发展奠定理论依据。1 材料与方法
1.1 试验区概况
试验在广西武鸣区广西农业科学院里建基地（N 23°14′49.0″,E 108°2′50.2″）进行,试验区地处亚热带,属典型的湿润季风气候,海拔120 m,光热资源充足,年均气温21.7℃,年均日照时数1 660 h,年均降雨量1 300 mm,降水量分布不均,多集中在7—9月。1.2 供试材料
1.2.1 供试作物 种植的甘蔗品种2008—2010年为新台糖22,2011—2013年为桂糖28,2014—2015年为桂糖29。1.2.2 供试土壤 试验地耕层土壤为赤红壤,试验开始前其理化性质为：pH（H2O）5.68,有机质20.1 g·kg-1,全氮0.85 g·kg-1,全磷0.12 g·kg-1,铵态氮5.58 mg·kg-1,硝态氮0.9 mg·kg-1,速效磷11 mg·kg-1,速效钾53 mg·kg-1。
1.3 试验设计
共设4个处理：（1）无肥处理（CK）;（2）推荐施肥（OPT）;（3）过量施氮（OPT+N）,氮肥施用量为OPT处理的1.5倍,磷钾肥施用量同OPT处理;（4）过量施磷（OPT+P）,磷肥施用量为OPT处理的1.5倍,氮钾肥施用量同OPT处理。3次重复,随机排列。小区面积24 m2（长8 m,宽3 m）,坡度5°。小区四周筑水泥作永久性田埂（宽12 cm,高40 cm,地下埋深30 cm）,以减少水分在小区间串流、测渗。每个小区外对应1个独立的容积为1.5 m3的径流收集池（长3 m、宽1 m、深0.5 m）,池内设有标尺杆,用于计量产流量。径流池上盖有盖子,以防雨水进入径流池。小区设置凹槽连通径流收集池。试验始于2008年2月至2016年1月,共种植了8茬甘蔗。种植制度为1年新植蔗2年宿根蔗。其中,2008、2011和2014年均为新植年份,2009、2012和2015年为第一年宿根、2010和2013年为第二年宿根。新植时,按1 m行距种植,每小区种植3行,每行48段双芽蔗茎节,品字型双行种植。新植蔗于每年2月底种植,来年1月中下旬收获,宿根蔗于每年2月底破垄,来年1月中旬收获。
OPT处理氮磷钾肥不实行统一定量,每年具体施肥量根据上茬土壤速效养分水平,甘蔗氮、磷、钾养分吸收量及目标产量等因素调整（表1）。各处理施用的氮磷钾肥均分别为尿素、钙镁磷肥（P2O5 18%）和氯化钾。新植蔗氮钾肥分3次施用,基肥、分蘖肥和伸长肥分别各占20%、30%和50%。宿根蔗氮钾肥分2次施用,分蘖肥和伸长肥各占30%和70%。新植蔗和宿根蔗磷肥均做基肥一次施用。基肥施于甘蔗种植沟底,然后盖层细土（5 cm）,分蘖肥与伸长肥采用撒施方式施于种植沟两旁,再培土。全生育期均无灌溉,为典型雨养农业。病虫害管理与当地甘蔗种植保持一致。
Table 1
表1
表1推荐施肥（OPT）处理的肥料施用量
Table 1Fertilizer application rate of OPT（kg·hm-2）
| 肥料 Fertilizer | 年份 Year | ||||||
|---|---|---|---|---|---|---|---|
| 2008 | 2009 | 2010 | 2011 （2012） | 2013 | 2014 | 2015 | |
| N | 450 | 450 | 300 | 450 | 400 | 450 | 404.4 |
| P2O5 | 120 | 120 | 120 | 135 | 120 | 135 | 135 |
| K2O | 300 | 217 | 217 | 257 | 257 | 257 | 240 |
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1.4 测定项目与方法
1.4.1 蔗茎样品的采集与测定 于收获期将各小区的甘蔗全部平地收获,脱叶,砍去尾梢,按实收株数测产蔗茎产量。1.4.2 径流水样的采集和测定 在甘蔗生长周期内采集。原则上于每次降雨产流后当天采集径流水样,遇多天连续小雨,则在产生的径流池水量达到径流池体积的80%后,计算1次径流量,但最大间隔一般不超过7 d。采样前,先记录径流池内的径流水面高度,然后用清洁工具充分搅匀径流池中的径流水,迅速用500 mL塑料瓶5 s内收集径流池内水。取样后,清洗径流池内的泥沙,以备收集下次降雨后的径流。径流水样带回实验室放入4℃冰箱保存,用于总氮（TN）和总磷（TP）测定。TN用过硫酸钾氧化-紫外分光光度计法测定[14];TP用过硫酸钾消解-钼锑抗分光光度法[15]测定。
1.4.3 计算方法 甘蔗产量稳定性分别以统计学上的变异系数（coefficient of variation,CV）和可持续产量指数（sustainable yield index,SYI）表示,CV越大说明产量稳定性越低,SYI指数越高则说明该系统的稳定性和可持续越好。计算公式分别为[2]：
CV=σ/
土壤地力贡献率、肥料贡献率与农学利用率的计算[16,17]。
土壤地力贡献率（%）=不施肥处理产量/施肥处理最高产量×100;
肥料贡献率（%）=（施肥处理产量-不施肥处理产量）/施肥处理产量×100;
农学利用率（kg·kg-1）=（施肥处理产量-不施肥处理产量）/（施氮量+施磷量+施钾量）×100;
地表径流氮（磷）流失量（kg·hm-2）=
液体积×TN（TP）含量;
肥料径流流失率（%）=（施肥处理氮（磷）流失量-不施肥处理氮（磷）流失量）/施氮（磷）量×100。
1.5 数据分析
用Microsoft Excel 2007整理数据,DPS 7.5软件分析数据,Origin 8.0软件作图。不同处理间多重比较采用Duncan新复极差法（α = 0.05）。2 结果
2.1 长期不同施肥下的甘蔗产量
由图1可以看出,随着种植年限的延长,在种植的前4年,CK处理甘蔗蔗茎产量急剧下降,后略有回升,并保持在50 t·hm-2,而施肥处理不同年份间的波动较大,呈锯齿状,但在相同年份内波动趋势基本相同,即同时上升或下降。
显示原图|下载原图ZIP|生成PPT图1长期不同施肥下甘蔗蔗茎年际产量及平均产量（t·hm-2）
-->Fig. 1Annual fluctuation and average sugarcane yield under long-term different fertilization
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由图1还可以看出, OPT、OPT+N和OPT+P处理均比CK显著提高甘蔗产量,8年平均蔗茎产量提高幅度分别为83.0%、72.6%和77.5%,增幅高达70%以上。说明该区获得甘蔗高产必须施肥,施肥是提高蔗区土壤生产力的重要途径。8年蔗茎平均产量,OPT处理与OPT+P处理相当,但显著高于OPT+N处理,说明持续过量施入磷肥对产量无显著影响,但过量施入氮肥会导致甘蔗减产。
2.2 长期不同施肥下的甘蔗蔗茎产量稳定性及可持续性
表2表明,甘蔗蔗茎产量的变异系（CV）以CK处理最大,显著高于施肥处理。相反,施肥处理的SYI指数显著高于CK处理。不同施肥处理（OPT、OPT+N和OPT+P）间的CV及SYI均无显著差异。说明当施肥量充足的时候,过量施入氮磷肥对蔗茎产量的稳定性与可持续性无提高优势。
Table 2
表2
表2长期不同施肥对甘蔗蔗茎产量变异系数及可持续性产量指数的影响
Table 2Effects of long-term different fertilization on the coefficient of variation and sustainable yield index of sugarcane stem
| 处理 Treatment | 变异系数 CV | 可持续性产量指数 SYI |
|---|---|---|
| CK | 0.23 a | 0.53 b |
| OPT | 0.11 b | 0.75 a |
| OPT+N | 0.12 b | 0.74 a |
| OPT+P | 0.12 b | 0.75 a |
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2.3 长期不同施肥下的土壤地力贡献率及肥料贡献率
土壤地力贡献率是反映土壤生产能力的指标,而肥料贡献率是肥料对作物产量的贡献率,把CK处理的产量视为土壤（地力）对产量的贡献,以其为基准进行计算,反映年投入肥料的生产能力的指标[17]。图2表明,土壤地力贡献率在试验的前4年由76.9%急剧下降至42.7%,之后回升至49.1%,并保持在50%左右浮动;长期施肥处理的肥料贡献率与地力贡献率呈显著负相关（P<0.05）,前4年由19.3%—23.1%急剧增加至56.7%—57.3%,3年后逐渐下降,6年后在47%范围内波动平衡。可见,赤红壤的养分供应能力随着甘蔗种植年限的延长而下降,甘蔗产量对肥料的依赖作用逐渐增加,直至50%左右时趋于平衡。
显示原图|下载原图ZIP|生成PPT图2长期不同施肥对土壤地力贡献率与肥料贡献率的影响
-->Fig. 2Effects of long-term different fertilization on the contribution of soil capacity and contribution rate of fertilizer
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图2还可以看出,8年肥料平均贡献率OPT处理与OPT+P处理均无显著差异（P>0.05）。但显著高于OPT+N处理（P<0.05）。说明过量施入磷肥对肥料的贡献率影响不大,但过量施入氮肥降低了肥料贡献率。
2.4 长期过量施入氮磷化肥的甘蔗肥料农学利用率
农学利用率是指单位施入养分量（N+P2O5+K2O）生产的经济收获物,反映了单位养分量增加作物产量的能力[17]。由表3可以看出,不同施肥处理肥料农学利用率的变幅为1.71—9.14 kg?kg-1。8年平均,OPT处理显著高于OPT+N处理43.4%和OPT+P处理16.0%（P<0.05）。说明过量施入氮磷肥降低肥料农学利用率,降幅尤以过量施氮最大。Table 3
表3
表3长期不同施肥对甘蔗肥料农学利用率的影响
Table 3Effects of long-term different fertilization on agronomic efficiency （kg?kg-1）
| 处理 Treatment | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 平均 Average |
|---|---|---|---|---|---|---|---|---|---|
| OPT | 2.72 a | 3.80 a | 9.14 a | 5.57 a | 6.27 a | 5.19 a | 5.73 a | 7.36 a | 5.72 a |
| OPT+N | 1.71 a | 2.79 b | 6.99 b | 4.40 b | 3.97 b | 3.02 c | 3.70 b | 5.33 c | 3.99 c |
| OPT+P | 2.23 a | 3.16 ab | 7.85 ab | 5.29 a | 5.40 a | 3.98 b | 5.14 a | 6.39 b | 4.93 b |
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2.5 蔗地地表径流氮磷流失量和肥料径流流失率
由图3可以看出,与CK相比,施肥显著提高蔗地地表径流氮磷流失量（P<0.05）,施肥处理8年氮平均流失量和磷平均流失量分别显著提高123%—195%和64%—117%。施肥处理下,氮流失量以OPT+N处理最高,显著高于OPT+P和OPT处理（P<0.05）,而OPT+P处理不同年份或显著高于或相当于 OPT处理。磷流失量以OPT+P处理最高,8年平均分别高于OPT+N和OPT处理23.6%和32.0%（P<0.05）,而OPT+N和OPT处理磷流失量相当,说明过量施入氮磷肥增加相应氮磷养分的地表径流流失量。
显示原图|下载原图ZIP|生成PPT图3长期不同施肥对蔗地地表径流氮磷流失量的影响
-->Fig. 3Effects of long-term different fertilization on N and P loss from runoff in sugarcane field
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从表4可以看出,施肥处理氮肥径流流失率和磷
肥径流流失率基本保持在5%以下。除了2008和2013年,其他年份,OPT、OPT+N和OPT+P 3个处理氮肥径流流失率和磷肥径流流失率均无显著差异。
Table 4
表4
表4长期不同施肥对肥料径流流失率的影响
Table 4Effects of long-term different fertilization on fertilizer loss rate
| 处理 Treatment | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 平均 Average |
|---|---|---|---|---|---|---|---|---|---|
| 氮肥径流流失率 N loss rate (%) | |||||||||
| OPT | 0.45 c | 0.59 a | 1.40 a | 3.43 a | 0.53 a | 1.18 b | 1.53 a | 1.80 a | 1.36 a |
| OPT+N | 0.83 a | 0.76 a | 1.60 a | 3.21 a | 0.53 a | 1.24 b | 1.40 a | 2.00 a | 1.45 a |
| OPT+P | 0.71 b | 0.53 a | 1.63 a | 3.39 a | 0.53 a | 1.68 a | 1.66 a | 1.89 a | 1.50 a |
| 磷肥径流流失率P loss rate (%) | |||||||||
| OPT | 0.81 a | 0.68 a | 1.88 a | 0.51 a | 0.81 a | 0.40 a | 0.38 a | 0.57 a | 0.76 b |
| OPT+N | 1.06 a | 1.02 a | 2.13 a | 0.77 a | 0.85 a | 0.34 a | 0.38 a | 0.56 a | 0.89 a |
| OPT+P | 1.09 a | 1.09 a | 2.15 a | 0.66 a | 0.86 a | 0.52 a | 0.40 a | 0.57 a | 0.92 a |
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3 讨论
3.1 施肥与甘蔗产量
作物生产的主要目标是提高产量[18]。产量的年际波动图可从时间上分析产量变化过程及趋势。不施肥的作物产量是土壤基础地力和环境的综合表现,在一定环境中不施肥作物的产量变化可以反映土壤基础地力演变状况。本试验结果显示,CK处理在试验前4年甘蔗蔗茎产量急剧下降, 4年后虽略有波动,但年际波动较为缓和,这主要与土壤基础地力的稳定性有关。众多研究表明,有机质是土壤基础地力的主要影响因素[6,19-20],其易分解组分经过矿化和腐殖化形成的腐殖质稳定性高,分解缓慢。本研究中,由于土壤基础地力处于中等水平（有机质20.1 g·kg-1）,因此,在经过一定年限后,土壤基础地力贡献率仍可稳定在一个较高水平（50%）。另一方面,农田下垫面大气氮沉降对作物产量的贡献作用在不断增强[21]。3个施肥处理蔗茎产量年际波动均较为剧烈,呈锯齿状,但在相同年份内波动趋势相同。将一个轮作年度内的甘蔗产量分别与月降雨量进行分析,发现新台糖22的产量与9月份的降雨量呈极显著相关,而桂糖28号与当年5月份的降雨量呈极显著相关（数据未列出）,因此,当施肥量充足的时候,甘蔗蔗茎产量的时间动态变化可能与不同甘蔗品种对生长季节的气候敏感度不同有关。这在其他研究中已经得到证实[22,23]。
甘蔗年均产量差异可反映施肥对甘蔗产量影响的长期积累效果。试验结果显示,与CK相比,施肥均能显著提高甘蔗蔗茎产量,说明施肥是南方赤红壤蔗区甘蔗产量提高的关键。从8年甘蔗蔗茎的平均产量来看,OPT处理与OPT+P处理相当,但显著高于OPT+N处理。说明过量施磷对甘蔗产量无显著影响,但过量施氮会降低甘蔗产量。这与廖文华等[24]在潮褐土蔬菜上的研究结果一致,究其原因与土壤供磷强度有关。当土壤供磷水平较高或高于一定值时,增施磷肥会降低磷肥利用效率,引起作物无增产效应[25,26]。本研究中,OPT与OPT+P处理均能较CK显著提升土壤速效磷含量,尤其OPT+P处理,磷在土壤中的累积量更大,土壤供磷强度增加,从而导致两者产量无显著差异。而过量施氮容易降低旗叶光合速率、群体冠层光合速率和作物生长速率从而抑制产量[27]。
综合比较4个处理甘蔗蔗茎产量的稳定性和可持续性,CK的甘蔗蔗茎产量CV最大,SYI最小,而施肥则可有效降低CV,提高SYI。说明不施肥条件下甘蔗的抗逆性较差,易造成产量大幅波动,施肥则有利于降低环境、生物与人为因素等对产量的影响,维持该生态系统的稳定性[28]。施肥处理间的CV和SYI均无显著差异,说明施肥虽然是增产的主要因素,但当施肥量已经充足的时候,过量施入氮磷肥并不增强蔗茎产量的稳定性。这与门明新等[3]的研究一致。
3.2 施肥与地力贡献率、肥料贡献率、肥料农学利用率
现代作物生产必须根据作物的施肥效应合理配置肥料资源,在保证作物高产的前提下,提高地力及肥料利用效率[17]。长期、多点、多区域的肥料试验证明,肥料贡献率及肥料农学利用率受作物类型、土壤条件、气候、施肥措施和其他因素的影响[17,29]。本研究结果显示, OPT处理与OPT+P处理8年肥料的平均贡献率无显著差异（P<0.05）,但显著高于OPT+N处理。肥料8年平均农学利用率OPT处理显著高于OPT+N和OPT+P处理,说明长期高量施入氮磷肥不仅造成肥料贡献率和农学利用率的下降,还可能成为环境污染的潜在威胁因子。3.3 施肥与径流养分流失、肥料径流流失率
研究结果显示,施肥对蔗地氮排放负荷的短暂性增加有很大的贡献[8]。年施入N 94 kg?hm-2较180 kg?hm-2可显著降低蔗地地表径流氮损失[9]。土壤侵蚀是蔗地磷流失的一个重要机制,径流水中89%的磷以颗粒态形式存在[30]。蔗地地表径流水的水质与径流沉淀物密切相关[31]。这些结果说明施肥可能通过作用于土壤肥力而影响径流养分损失。本研究结果表明,施肥显著提高蔗地地表径流氮磷流失量,尤其过量施入氮磷肥会显著提高相应氮磷养分的径流流失量。这主要是在同一气候、土壤条件下,养分投入量是影响径流水中氮磷养分浓度高低的主要原因[32]。本试验结果还显示,OPT、OPT+N和OPT+P处理的氮（磷）肥径流流失率相当,即推荐施肥在氮（磷）流失量方面虽然比过量施氮和过量施磷处理显著下降,但氮（磷）肥径流流失率却未有一致表现。原因是推荐施肥在降低氮（磷）流失量的同时相应降低了氮（磷）肥的投入量。
4 结论
长期推荐施肥有利于提高甘蔗产量及其稳定性,而过量施氮、过量施磷对甘蔗产量及其稳定性无显著提高作用。相反,降低了肥料贡献率和农学利用率,促进了相应养分的径流流失量。因此,过量施氮和过量施磷不仅没有增产、稳产优势,还显著造成资源浪费和养分流失。在南方赤红壤蔗区,推荐施肥是一种兼顾甘蔗稳产高产和径流养分流失低的较好施肥措施。The authors have declared that no competing interests exist.
参考文献 原文顺序
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被引期刊影响因子
| [1] | . 【Objective】 Effects of long-term fertilization on rice yield and its stability of double cropping rice system was studed in this paper.【Method】 Fertilization, environment and their interactions were analyzed by AMMI (additive main effects and multiplicative interaction) model based on a 25-year long-term fertilizer experiment conducted in yellow clayey soil in Nanchang of Jiangxi Province. At this site, 8 treatments were established in 1984. They were in a early rice late rice rotation receiving no fertilizer(CK)，nitrogen fertilizers deficiency (PK), potassium fertilizers deficiency (NP), phosphorus fertilizers deficiency (NK), balanced chemical fertilizers application (NPK), substitution of 70% inorganic N by 30% organic N in balanced chemical fertilizers application (70F+30M), substitution of 50% inorganic N by 50% organic N in balanced chemical fertilizers application (50F+50M)，substitution of 30% inorganic N by 70% organic N in balanced chemical fertilizers application (70F+30M).【Result】Two main results obtained from this analysis showed as follows. Firstly, the sum of squares of fertilization treatments by environment interactions (F×E) was 9.78% of total sum of squares, and achieved a significant difference at 1% level from AMMI model analysis, from which IPCA1, IPCA2, IPCA3 explained 88.46% sum of squares of the interactions. Coefficients of correlations which were significant correlations between the stability parameters and Shukla coefficient of variation or coefficient of variation were 0.97 and 0.83. Secondly, balanced chemical fertilizers application (NPK) treatment could be good for improving the rice yield and its stability of double cropping rice system. Partial substitution of chemical fertilizers by organic manure made further improvement in rice yield and its stability under the equal nutrient amount application condition, compared with NPK treatment. The yields of substitution application of 30%, 50% and 70% of chemical fertilizer by organic fertilizer treatments increased by 6.15%, 3.88%, and 7.75%, respectively, and rice yield stability increased by 25.91%, 59.78%, and 29.31%, respectively. 【Conclusion】 The AMMI model clearly explained the interactive effects of fertilization treatments across environment (F×E). It was a good method for evaluating stability of double cropping rice yield under long-term fertilization. It was concluded that combined application of organic manure and chemical fertilizers was the best fertilization on achieving high and stable yield of double cropping rice in the region. Stability of the treatment combined application of 50% organic manure combined with 50% chemical fertilizers was the best under relatively high yield conditions. Treatments combined application of 30% or 70% organic manure with 70% or 30% chemical fertilizers obtained the highest yield and the best adaptability under the more stable circumstances. . 【Objective】 Effects of long-term fertilization on rice yield and its stability of double cropping rice system was studed in this paper.【Method】 Fertilization, environment and their interactions were analyzed by AMMI (additive main effects and multiplicative interaction) model based on a 25-year long-term fertilizer experiment conducted in yellow clayey soil in Nanchang of Jiangxi Province. At this site, 8 treatments were established in 1984. They were in a early rice late rice rotation receiving no fertilizer(CK)，nitrogen fertilizers deficiency (PK), potassium fertilizers deficiency (NP), phosphorus fertilizers deficiency (NK), balanced chemical fertilizers application (NPK), substitution of 70% inorganic N by 30% organic N in balanced chemical fertilizers application (70F+30M), substitution of 50% inorganic N by 50% organic N in balanced chemical fertilizers application (50F+50M)，substitution of 30% inorganic N by 70% organic N in balanced chemical fertilizers application (70F+30M).【Result】Two main results obtained from this analysis showed as follows. Firstly, the sum of squares of fertilization treatments by environment interactions (F×E) was 9.78% of total sum of squares, and achieved a significant difference at 1% level from AMMI model analysis, from which IPCA1, IPCA2, IPCA3 explained 88.46% sum of squares of the interactions. Coefficients of correlations which were significant correlations between the stability parameters and Shukla coefficient of variation or coefficient of variation were 0.97 and 0.83. Secondly, balanced chemical fertilizers application (NPK) treatment could be good for improving the rice yield and its stability of double cropping rice system. Partial substitution of chemical fertilizers by organic manure made further improvement in rice yield and its stability under the equal nutrient amount application condition, compared with NPK treatment. The yields of substitution application of 30%, 50% and 70% of chemical fertilizer by organic fertilizer treatments increased by 6.15%, 3.88%, and 7.75%, respectively, and rice yield stability increased by 25.91%, 59.78%, and 29.31%, respectively. 【Conclusion】 The AMMI model clearly explained the interactive effects of fertilization treatments across environment (F×E). It was a good method for evaluating stability of double cropping rice yield under long-term fertilization. It was concluded that combined application of organic manure and chemical fertilizers was the best fertilization on achieving high and stable yield of double cropping rice in the region. Stability of the treatment combined application of 50% organic manure combined with 50% chemical fertilizers was the best under relatively high yield conditions. Treatments combined application of 30% or 70% organic manure with 70% or 30% chemical fertilizers obtained the highest yield and the best adaptability under the more stable circumstances. |
| [2] | . 【目的】分析长期施肥条件下小麦产量的变化规律，试图探明淮北小麦产量稳定性对不同施肥模式的响应机制，为淮北砂姜黑土合理施肥管理、改善农田生态系统质量提供依据。【方法】以安徽杨柳长期定位试验为研究平台，通过研究小麦的平均产量、产量年际波动及土壤养分状况对5种施肥模式（不施肥、单施化肥、单施有机肥、有机肥与化肥配施（等氮）、有机肥与化肥配施（高氮））的响应，比较不同施肥条件下淮北砂姜黑土区小麦产量稳定性的优劣，并以此评判施肥的合理性。【结果】淮北砂姜黑土区长期不施肥的小麦产量总体呈下降趋势，年下降量为5.81 kg•hm-2；而长期施肥的小麦产量随时间呈锯齿状波动并总体上升的趋势，其中有机肥与化肥配施（高氮）处理（HMNPK）的产量趋势线最高，但其增产优势逐年减弱，有机肥与化肥配施（等氮）处理（MNPK）以9.75 kg•hm-2的年增长量缩短与其的差距；单施化肥处理（NPK）的小麦产量趋势线在试验前期高于单施有机肥（M），但在22年后有被M处理赶超的趋势。从32年小麦平均产量来看，与不施肥相比，有机肥与化肥配施（高氮与等氮）的增产幅度最大，平均产量分别达5 544.3和5 200.6 kg•hm-2；NPK次之，比当年不施肥处理产量提高了614.6%，M增产幅度最低，但与NPK差异并不明显。砂姜黑土地力贡献率在试验前10年持续降低，降至10%左右趋于稳定，而肥料对小麦产量的贡献率则是在前10年持续增加至80%—90%便维持动态平衡。长期不施肥易导致小麦产量变异系数（CV）偏高、可持续性产量指数（SYI）偏低，产量稳定性最低；施肥处理中HMNPK和MNPK处理的CV最低、SYI最高，产量稳定性最高，而M处理的产量稳定性和可持续性不及NPK。与长期不施肥相比，施肥可明显提高淮北砂姜黑土全氮、有机质、有效磷和速效钾的含量，其中有机肥的施入显著提高了土壤全氮和有机质含量，而有效磷含量与化肥的投入相关，处理M土壤速效钾含量较高，但与其他施肥处理差异不显著；通过相关性分析可知全氮、有机质、有效磷含量与小麦产量呈极显著正相关关系（P＜0.01）。【结论】施肥可有效提高淮北小麦产量，且产量随时间呈锯齿状波动；有机肥与化肥配施（高氮和等氮）的增产效果最佳，但高氮与等氮水平间的产量差随种植年限的增长而逐渐缩短；在试验开始前一阶段单施化肥的增产效果优于单施有机肥处理，但在22年后有被赶超的趋势。与长期不施肥相比，有机肥与化肥配施的施肥模式更有利于促进小麦产量稳定性和生产可持续性的提高，其次为单施化肥，单施有机肥最低。施肥可有效提高砂姜黑土养分含量，其中有机肥对有机质、全氮及速效钾含量的提高作用较强，而化肥则对有效磷含量提高作用较强，且小麦产量与全氮、有机质和有效磷均呈极显著正相关关系。因此，安徽淮北砂姜黑土区有机肥与化肥配施为最佳施肥模式，土壤养分供应较均衡，小麦产量幅度最大且稳定性最佳，农田生态系统质量最优。 . 【目的】分析长期施肥条件下小麦产量的变化规律，试图探明淮北小麦产量稳定性对不同施肥模式的响应机制，为淮北砂姜黑土合理施肥管理、改善农田生态系统质量提供依据。【方法】以安徽杨柳长期定位试验为研究平台，通过研究小麦的平均产量、产量年际波动及土壤养分状况对5种施肥模式（不施肥、单施化肥、单施有机肥、有机肥与化肥配施（等氮）、有机肥与化肥配施（高氮））的响应，比较不同施肥条件下淮北砂姜黑土区小麦产量稳定性的优劣，并以此评判施肥的合理性。【结果】淮北砂姜黑土区长期不施肥的小麦产量总体呈下降趋势，年下降量为5.81 kg•hm-2；而长期施肥的小麦产量随时间呈锯齿状波动并总体上升的趋势，其中有机肥与化肥配施（高氮）处理（HMNPK）的产量趋势线最高，但其增产优势逐年减弱，有机肥与化肥配施（等氮）处理（MNPK）以9.75 kg•hm-2的年增长量缩短与其的差距；单施化肥处理（NPK）的小麦产量趋势线在试验前期高于单施有机肥（M），但在22年后有被M处理赶超的趋势。从32年小麦平均产量来看，与不施肥相比，有机肥与化肥配施（高氮与等氮）的增产幅度最大，平均产量分别达5 544.3和5 200.6 kg•hm-2；NPK次之，比当年不施肥处理产量提高了614.6%，M增产幅度最低，但与NPK差异并不明显。砂姜黑土地力贡献率在试验前10年持续降低，降至10%左右趋于稳定，而肥料对小麦产量的贡献率则是在前10年持续增加至80%—90%便维持动态平衡。长期不施肥易导致小麦产量变异系数（CV）偏高、可持续性产量指数（SYI）偏低，产量稳定性最低；施肥处理中HMNPK和MNPK处理的CV最低、SYI最高，产量稳定性最高，而M处理的产量稳定性和可持续性不及NPK。与长期不施肥相比，施肥可明显提高淮北砂姜黑土全氮、有机质、有效磷和速效钾的含量，其中有机肥的施入显著提高了土壤全氮和有机质含量，而有效磷含量与化肥的投入相关，处理M土壤速效钾含量较高，但与其他施肥处理差异不显著；通过相关性分析可知全氮、有机质、有效磷含量与小麦产量呈极显著正相关关系（P＜0.01）。【结论】施肥可有效提高淮北小麦产量，且产量随时间呈锯齿状波动；有机肥与化肥配施（高氮和等氮）的增产效果最佳，但高氮与等氮水平间的产量差随种植年限的增长而逐渐缩短；在试验开始前一阶段单施化肥的增产效果优于单施有机肥处理，但在22年后有被赶超的趋势。与长期不施肥相比，有机肥与化肥配施的施肥模式更有利于促进小麦产量稳定性和生产可持续性的提高，其次为单施化肥，单施有机肥最低。施肥可有效提高砂姜黑土养分含量，其中有机肥对有机质、全氮及速效钾含量的提高作用较强，而化肥则对有效磷含量提高作用较强，且小麦产量与全氮、有机质和有效磷均呈极显著正相关关系。因此，安徽淮北砂姜黑土区有机肥与化肥配施为最佳施肥模式，土壤养分供应较均衡，小麦产量幅度最大且稳定性最佳，农田生态系统质量最优。 |
| [3] | . 【目的】研究长期施肥处理对华北平原潮土作物产量及稳定性的影响，为维持田块尺度粮食高产、稳产、高效提供指导。【方法】采用长期定位试验中不同肥料处理与多种稳定性指数方法分析作物产量效应及稳定性。【结果】经过7年定位施肥试验，CK、P2K2、N2K2和N2P2处理的小麦产量分别为N2P2K2处理的25．5％、34．5％、43．3％和83．2％；玉米产量分别为42．3％、52．7％、70．6％和76．2％；不施氮肥，土壤氮自然供给力第1年降到59％，第2年为43％，此后稳定在40％左右；不施磷肥，土壤磷自然供给力第1年降至72％，第3年为55％，之后保持在55％左右；不施钾肥，土壤钾自然供给力第1年降为93％，第3年为76％，之后基本不变；7年累计，小麦、玉米及全年作物产量稳定性最强的处理分别为N1P2K2、N2P2K2和N1P2K2。【结论】作物产量效应与施肥量有明显相关性，产量稳定性与施肥量无明显关系，但与氮、磷、钾肥配比明显相关。 . 【目的】研究长期施肥处理对华北平原潮土作物产量及稳定性的影响，为维持田块尺度粮食高产、稳产、高效提供指导。【方法】采用长期定位试验中不同肥料处理与多种稳定性指数方法分析作物产量效应及稳定性。【结果】经过7年定位施肥试验，CK、P2K2、N2K2和N2P2处理的小麦产量分别为N2P2K2处理的25．5％、34．5％、43．3％和83．2％；玉米产量分别为42．3％、52．7％、70．6％和76．2％；不施氮肥，土壤氮自然供给力第1年降到59％，第2年为43％，此后稳定在40％左右；不施磷肥，土壤磷自然供给力第1年降至72％，第3年为55％，之后保持在55％左右；不施钾肥，土壤钾自然供给力第1年降为93％，第3年为76％，之后基本不变；7年累计，小麦、玉米及全年作物产量稳定性最强的处理分别为N1P2K2、N2P2K2和N1P2K2。【结论】作物产量效应与施肥量有明显相关性，产量稳定性与施肥量无明显关系，但与氮、磷、钾肥配比明显相关。 |
| [4] | . . |
| [5] | . 通过10年稻—麦水旱轮作定位试验,研究了紫色土生产力以及N、P、K自然供应能力和变化。结果表明,在水旱轮作下,紫色土对稻、麦产量的地力贡献率平均为58%和51%,肥料的增产贡献率可达42%～49%。紫色土N、P、K养分自然供给力在小麦上分别为60%、70%、91%,在水稻上分别为70%、90%、92%,小麦对肥料的依赖性高于水稻;N、P、K养分的自然供应量在小麦上分别为37 1、5 4、45 9kg hm2,在水稻上分别为81 8、13 6、103 0kg hm2。随着试验年份的延长,旱作季节紫色土N、P、K养分的供应能力逐年降低,水作季节N、P、K供应力则相对稳定,旱作对地力的消耗比水作大。环境输入的养分在维持水田稳定供肥能力发挥了重要作用。紫色土这种基础养分供给力可维持每年生产小麦1 4t hm2、稻谷3 5t hm2左右。 . 通过10年稻—麦水旱轮作定位试验,研究了紫色土生产力以及N、P、K自然供应能力和变化。结果表明,在水旱轮作下,紫色土对稻、麦产量的地力贡献率平均为58%和51%,肥料的增产贡献率可达42%～49%。紫色土N、P、K养分自然供给力在小麦上分别为60%、70%、91%,在水稻上分别为70%、90%、92%,小麦对肥料的依赖性高于水稻;N、P、K养分的自然供应量在小麦上分别为37 1、5 4、45 9kg hm2,在水稻上分别为81 8、13 6、103 0kg hm2。随着试验年份的延长,旱作季节紫色土N、P、K养分的供应能力逐年降低,水作季节N、P、K供应力则相对稳定,旱作对地力的消耗比水作大。环境输入的养分在维持水田稳定供肥能力发挥了重要作用。紫色土这种基础养分供给力可维持每年生产小麦1 4t hm2、稻谷3 5t hm2左右。 |
| [6] | . 农田基础地力提升对于减施肥料和作物稳产高产有着重大现实意义,该文依托潮土长期定位试验,采用DSSAT(decision support system for agro-technology transfer)模型分析了长期不同施肥条件下冬小麦农田基础地力的演变规律及其影响因素。结果表明,不同施肥显著影响冬小麦的农田基础地力产量,18a连续施用氮磷钾化肥(NPK)、NPK配施有机肥(NPKM)、高量NPK配施有机肥(1.5NPKM)和NPK配施秸秆还田(NPKS)的农田基础地力均得到提升,其基础地力产量分别增加了721、1033、2108和1306kg/hm2,增长率分别为29.6%、42.4%、86.6%和53.7%,平均每年提高1.6%、2.4%、4.8%和3.0%,其中以1.5NPKM处理更能有效提高冬小麦农田基础地力产量。1991-2008年冬小麦的基础地力贡献率在36.5%～70.9%,各处理18a年均基础地力贡献率分别为42.5%、59.9%、58.9%和52.5%,大小顺序为NPKM1.5NPKMNPKSNPK,说明有机肥或秸秆与化肥配施比单施化肥更能有效提高农田基础地力产量及地力贡献率。基础地力贡献率与土壤全钾、全磷含量无显著相关性,与土壤有机碳、全氮、碱解氮、有效磷、速效钾含量均达到了极显著相关,其中有机碳和全氮与基础地力贡献率相关度最高,说明土壤有机碳和全氮是潮土区基础地力的主要影响因素,是潮土区基础地力的主要评价指标。 . 农田基础地力提升对于减施肥料和作物稳产高产有着重大现实意义,该文依托潮土长期定位试验,采用DSSAT(decision support system for agro-technology transfer)模型分析了长期不同施肥条件下冬小麦农田基础地力的演变规律及其影响因素。结果表明,不同施肥显著影响冬小麦的农田基础地力产量,18a连续施用氮磷钾化肥(NPK)、NPK配施有机肥(NPKM)、高量NPK配施有机肥(1.5NPKM)和NPK配施秸秆还田(NPKS)的农田基础地力均得到提升,其基础地力产量分别增加了721、1033、2108和1306kg/hm2,增长率分别为29.6%、42.4%、86.6%和53.7%,平均每年提高1.6%、2.4%、4.8%和3.0%,其中以1.5NPKM处理更能有效提高冬小麦农田基础地力产量。1991-2008年冬小麦的基础地力贡献率在36.5%～70.9%,各处理18a年均基础地力贡献率分别为42.5%、59.9%、58.9%和52.5%,大小顺序为NPKM1.5NPKMNPKSNPK,说明有机肥或秸秆与化肥配施比单施化肥更能有效提高农田基础地力产量及地力贡献率。基础地力贡献率与土壤全钾、全磷含量无显著相关性,与土壤有机碳、全氮、碱解氮、有效磷、速效钾含量均达到了极显著相关,其中有机碳和全氮与基础地力贡献率相关度最高,说明土壤有机碳和全氮是潮土区基础地力的主要影响因素,是潮土区基础地力的主要评价指标。 |
| [7] | . Phosphorus losses in runoff from sugarcane fields can contribute to non-point source pollution of surface and subsurface waters. The objective of this study was to evaluate the effects of three different management practices on P losses in surface runoff and subsurface leaching from sugarcane ( Saccharum officinarum L.) fields. Field experiments with treatments including conventional burning (CB), compost application with burning (COMB), and remaining green cane trash blanketing (GCTB) treatments were carried out to assess these management practice effects on P losses from sugarcane fields. In the CB treatment, sugarcane residue was burned after harvest. The COMB treatment consisted of compost applied at “off bar” with sugarcane residue burned immediately after harvest. Compost was applied in the amount of 13.402Mg02ha 611 annually, 802weeks before planting. In the GCTB treatment, sugarcane residue was raked off from the row tops and remained in the wheel furrow after harvest. Surface runoff was collected with automatic refrigerated samplers, and subsurface leachate was collected with pan lysimeters over a period of 302years. Measured concentrations of total P (TP), dissolved reactive P (DRP), and particulate P (PP) in surface runoff from the COMB treatment were significantly higher than concentrations from the CB and GCTB treatments. The mean losses of P (TP and DRP) after burning (postharvest, years022 and 3) were significantly greater than the no-burn treatment (preharvest, year021) in the CB, COMB, and CB/COMB/GCTB combined options. Additionally, the mean losses of total suspended solid and total combustible solids in residue burning were, on average, 2.7 and 2.2 times higher than the no-burn practices, respectively (preharvest and GCTB treatment). Annual P losses from surface runoff in the third year of study were 12.90%, 6.86%, and 10.23% of applied P in CB, COMB, and GCTB treatments, respectively. However, the percent of annual DRP losses from applied P in COMB and GCTB treatments was similar magnitude, and their values were less than 50% compared to the value from CB treatment. In the leaching study, percent of monthly mean TP and DRP losses in the COMB and GCTB treatments were greatly reduced. Based on these results, the COMB and GCTB procedures were equally recommended as sugarcane management practices that improve water quality in both surface runoff and subsurface leachate. |
| [8] | . A watershed analysis of nonpoint-source pollution associated with sugarcane (Saccharum officinarum L.) production was conducted. Runoff water samples following major rainfall events from two representative sugarcane fields (SC1 and SC2) were collected and analyzed. The impact of runoff on two receiving water bodies, St. James canal (SJC) and Bayou Chevreuil (BC) in a drainage basin (Baratarian Basin), was studied. Results show that runoff flow/rainfall ratios at the SC1 were significantly higher (P < 0.0001, n = 14) than at the SC2, probably mainly due to higher sand content and higher infiltration rate of surface soil at the SC2. In runoff water samples, total suspended solids (TSS) showed a significant correlation with the concentrations of N and P. Sugarcane runoff showed a direct impact on the SJC and BC locations where seasonal variations of pollutant concentrations in the waters followed the patterns of runoff loadings. Swamp forest runoff (SFR) location showed a buffering effect of forested wetlands on water quality with the lowest measured pollutant concentrations. The ratios in total N/total P and in inorganic N/organic N in runoff waters indicated that fertilization in spring greatly contributed to the temporal increase of N loadings, especially in forms of inorganic N. Isotope signature of 15N-nitrate in the water samples verified that the nitrate was derived from fertilizers and was consumed during transportation. Both N and P concentrations in the receiving water bodies were above the eutrophic level. During the study period, herbicide concentrations in the receiving water bodies rarely exceeded the drinking water standards. |
| [9] | . Nitrogen (N) lost from farms, especially as the highly bioavailable dissolved inorganic form, may be damaging Australia’s Great Barrier Reef (GBR). As sugarcane is the dominant cropping system in GBR catchments, its N management practises are coming under increasing scrutiny. This study measured dissolved inorganic N lost in surface runoff water and sugarcane productivity over 3years. The experiment compared the conventional fertiliser N application rate to sugarcane (average 180kgN/ha/year) and a rate based on replacing N exported in the previous crop (average 94kgN/ha/year). Dissolved inorganic N losses in surface water were 72%, 48% and 66% lower in the three monitored years in the reduced N fertiliser treatment. There was no significant difference in sugarcane yield between the two fertiliser N treatments, nor any treatment difference in soil mineral N – both of these results are indicators of the sustainability of the lower fertiliser N applications. |
| [10] | . 重点分析了我国甘蔗及制品质量与技术标准的研究进展及存在的问题,指出国内现行的甘蔗产业标准存在的一些问题,提出应尽快构建符合我国甘蔗产业发展需要的甘蔗及制品质量与技术标准的建议,并提出可从技术标准等3个方面对我国甘蔗产业标准进行研究. . 重点分析了我国甘蔗及制品质量与技术标准的研究进展及存在的问题,指出国内现行的甘蔗产业标准存在的一些问题,提出应尽快构建符合我国甘蔗产业发展需要的甘蔗及制品质量与技术标准的建议,并提出可从技术标准等3个方面对我国甘蔗产业标准进行研究. |
| [11] | . A field experiment of reduction fertilization on sugarcane was conducted to offer a technological support for irrigating and fertilizing on sugarcane scientifically. The results showed that the Nitrogen（N）, Phosphorous （P2O5）and potassium（K2O）uptake rate and their absorptive intensities in different growth stages of sugarcane by reduction fertilization under drip irrigation were significantly higher than those in conventional fertilization. In addition, the cane yield and quality of sugarcane under drip irrigation were also significantly increased than those in latter treatment. These results indicated that the cost of fertilizer could be reduced and the fertilizer use efficiency could be increased under drip irrigation. However, the net benefit of sugarcane production was increased by fertigation treatment only which compared to the conventional fertilization. . A field experiment of reduction fertilization on sugarcane was conducted to offer a technological support for irrigating and fertilizing on sugarcane scientifically. The results showed that the Nitrogen（N）, Phosphorous （P2O5）and potassium（K2O）uptake rate and their absorptive intensities in different growth stages of sugarcane by reduction fertilization under drip irrigation were significantly higher than those in conventional fertilization. In addition, the cane yield and quality of sugarcane under drip irrigation were also significantly increased than those in latter treatment. These results indicated that the cost of fertilizer could be reduced and the fertilizer use efficiency could be increased under drip irrigation. However, the net benefit of sugarcane production was increased by fertigation treatment only which compared to the conventional fertilization. |
| [12] | . . |
| [13] | . 长期来,我区甘蔗生产施肥具有施肥量大、肥料利用率低和施肥成本高等特点,除地租外,甘蔗施肥占甘蔗生产成本40%-50%。近年的研究结果指出,选择适合的肥料类型、采用正确的施肥位置、施用时间和施肥量等是降低甘蔗施肥成本的技术关键;选用富含腐殖酸的肥料有机-无机复合肥能显著提高甘蔗对肥料的利用率,同时肥效长,能满足甘蔗一次性追肥的需要;甘蔗减量30%-40%施肥量,能维持在亩产6-8吨的生产水平;为此,甘蔗种植区推荐亩施肥量:亩产原料蔗6-8吨,施N 18-20公斤,P2O56-7公斤,K2O 16-18公斤;有灌溉条件的甘蔗亩产原料蔗12-16吨,施N 23-28公斤,P2O58-9公斤,K2O 21-25公斤;基肥在开行沟后,占总施肥量10%;追肥在苗齐后施用。 . 长期来,我区甘蔗生产施肥具有施肥量大、肥料利用率低和施肥成本高等特点,除地租外,甘蔗施肥占甘蔗生产成本40%-50%。近年的研究结果指出,选择适合的肥料类型、采用正确的施肥位置、施用时间和施肥量等是降低甘蔗施肥成本的技术关键;选用富含腐殖酸的肥料有机-无机复合肥能显著提高甘蔗对肥料的利用率,同时肥效长,能满足甘蔗一次性追肥的需要;甘蔗减量30%-40%施肥量,能维持在亩产6-8吨的生产水平;为此,甘蔗种植区推荐亩施肥量:亩产原料蔗6-8吨,施N 18-20公斤,P2O56-7公斤,K2O 16-18公斤;有灌溉条件的甘蔗亩产原料蔗12-16吨,施N 23-28公斤,P2O58-9公斤,K2O 21-25公斤;基肥在开行沟后,占总施肥量10%;追肥在苗齐后施用。 |
| [14] | |
| [15] | |
| [16] | . 采用田间监测方法,研究了甘蔗种植体系中不同施肥模式下地表径流 引起的水土流失及氮磷流失特点.结果表明,广西旱地平原区缓坡地种植甘蔗的条件下,降雨后产生的径流系数为10％左右.甘蔗叶覆盖地面处理很少发生地表径 流,表明地表覆盖是影响地表径流的最重要的因素.径流量的大小与甘蔗生长的茂密程度有关,空白处理的甘蔗生长最差,其产生的地表径流量也高于各施肥处理, 表明甘蔗生长封行后,叶片阻断了雨水对土面的冲刷,也能有效减轻地表径流.在种植甘蔗的模式下,每年的泥沙流失量为2700 ～3000 kg·hm-2左右.施肥后通过地表径流流失的N、P比率均很低,氮肥的流失系数平均为0.778％～1.328％.磷肥的流失系数平均为1.104％ ～1.428％.增施N、P肥均可提高径流水的N、P含量,绝对量增加50％,流失系数略有增加. . 采用田间监测方法,研究了甘蔗种植体系中不同施肥模式下地表径流 引起的水土流失及氮磷流失特点.结果表明,广西旱地平原区缓坡地种植甘蔗的条件下,降雨后产生的径流系数为10％左右.甘蔗叶覆盖地面处理很少发生地表径 流,表明地表覆盖是影响地表径流的最重要的因素.径流量的大小与甘蔗生长的茂密程度有关,空白处理的甘蔗生长最差,其产生的地表径流量也高于各施肥处理, 表明甘蔗生长封行后,叶片阻断了雨水对土面的冲刷,也能有效减轻地表径流.在种植甘蔗的模式下,每年的泥沙流失量为2700 ～3000 kg·hm-2左右.施肥后通过地表径流流失的N、P比率均很低,氮肥的流失系数平均为0.778％～1.328％.磷肥的流失系数平均为1.104％ ～1.428％.增施N、P肥均可提高径流水的N、P含量,绝对量增加50％,流失系数略有增加. |
| [17] | . 【目的】研究在当前生产条件下化肥施用对不同作物产量的影响,明确化肥对不同作物产量的贡献 率及肥料的农学利用率现状。【方法】2006年至2008年在湖北省分别布置水稻、小麦、油菜和棉花的田间肥效试验251、47、62和26个,分析研究 氮、磷、钾肥配合施用对农作物的增产效果,以及目前不同作物的肥料贡献率和肥料农学利用率现状。【结果】目前农作物平衡施用氮、磷、钾肥的增产效果显著, 但不同作物的施肥效应差异较大。与不施肥相比,水稻、小麦、油菜和棉花平衡施用氮、磷、钾肥分别平均增产2269、2200、1438和 1617kg·hm-2,增产率分别为46.7%、109.8%、173.7%和68.6%;相对应的肥料对产量的贡献率分别为29.6%、48.6%、 56.2%和38.0%,肥料农学利用率分别为7.2、7.7、4.0和3.0kg·kg-1。【结论】现代作物产量的提高和维持必须依赖肥料的施用,并 且应该根据不同作物的施肥效应合理配置肥料资源,同时在保证农作物高产的前提下,提高肥料的利用效率。 . 【目的】研究在当前生产条件下化肥施用对不同作物产量的影响,明确化肥对不同作物产量的贡献 率及肥料的农学利用率现状。【方法】2006年至2008年在湖北省分别布置水稻、小麦、油菜和棉花的田间肥效试验251、47、62和26个,分析研究 氮、磷、钾肥配合施用对农作物的增产效果,以及目前不同作物的肥料贡献率和肥料农学利用率现状。【结果】目前农作物平衡施用氮、磷、钾肥的增产效果显著, 但不同作物的施肥效应差异较大。与不施肥相比,水稻、小麦、油菜和棉花平衡施用氮、磷、钾肥分别平均增产2269、2200、1438和 1617kg·hm-2,增产率分别为46.7%、109.8%、173.7%和68.6%;相对应的肥料对产量的贡献率分别为29.6%、48.6%、 56.2%和38.0%,肥料农学利用率分别为7.2、7.7、4.0和3.0kg·kg-1。【结论】现代作物产量的提高和维持必须依赖肥料的施用,并 且应该根据不同作物的施肥效应合理配置肥料资源,同时在保证农作物高产的前提下,提高肥料的利用效率。 |
| [18] | . |
| [19] | . . |
| [20] | . Crop yields, soil fertility and nutrient balance were studied systematically according to the results of a 23-year located experiment and the relative fertilizer experiments in wheat. The results show that the correlation between the contribution of soil f . Crop yields, soil fertility and nutrient balance were studied systematically according to the results of a 23-year located experiment and the relative fertilizer experiments in wheat. The results show that the correlation between the contribution of soil f |
| [21] | . . |
| [22] | |
| [23] | . 利用2000–2011年广西4个农业气象试验站的甘蔗旬茎伸长量和气象资料,分析宿根蔗和新植蔗在气象因子影响下茎伸长的差异。结果表明,新植蔗和宿根蔗茎生长具有明显差异,新植蔗茎伸长期茎高明显大于宿根蔗,进入茎生长期时的茎高本底值较小,茎总伸长量较大但其伸长期较短。多数气象因子与新植蔗、宿根蔗旬茎伸长量极显著相关（P〈0.05）,且对新植蔗的影响大于宿根蔗。对新植蔗、宿根蔗茎伸长起直接正作用的主要因子均为最低气温、相对湿度、最高气温,起直接负作用的主要因子为平均气温、气压,积温、降雨量则通过其他气象因子起明显的间接作用。旬茎伸长量对降雨量存在较明显的滞后性,新植蔗滞后期多为2旬,宿根蔗多为1旬,新植蔗对日照时数的响应也存在滞后现象,两者对温度类气象因子及相对湿度均无滞后。 . 利用2000–2011年广西4个农业气象试验站的甘蔗旬茎伸长量和气象资料,分析宿根蔗和新植蔗在气象因子影响下茎伸长的差异。结果表明,新植蔗和宿根蔗茎生长具有明显差异,新植蔗茎伸长期茎高明显大于宿根蔗,进入茎生长期时的茎高本底值较小,茎总伸长量较大但其伸长期较短。多数气象因子与新植蔗、宿根蔗旬茎伸长量极显著相关（P〈0.05）,且对新植蔗的影响大于宿根蔗。对新植蔗、宿根蔗茎伸长起直接正作用的主要因子均为最低气温、相对湿度、最高气温,起直接负作用的主要因子为平均气温、气压,积温、降雨量则通过其他气象因子起明显的间接作用。旬茎伸长量对降雨量存在较明显的滞后性,新植蔗滞后期多为2旬,宿根蔗多为1旬,新植蔗对日照时数的响应也存在滞后现象,两者对温度类气象因子及相对湿度均无滞后。 |
| [24] | . 【目的】研究长期连续过量施用磷肥下蔬菜的产量响应、磷肥去向及土壤各形态磷库的动态变化。【方法】在太行山山前平原典型潮褐土上,连续进行11年21茬露地蔬菜的长期定位肥料试验,P2O5年施用量设0（P0）、360（P1）、720（P2）、1080（P3）、1440（P4）kg/hm^2共5个处理,分别测定每茬蔬菜产量及各年土壤不同形态磷素含量。【结果】与不施磷肥处理比较,单季P2O5用量180、360、540、720 kg/hm^2均显著增加大白菜、菜豆产量,不同磷肥用量间蔬菜产量均无显著差异。P2O5年用量为360、720、1080、1440 kg/hm^2,土壤年盈余磷为41.2-478.7 kg/hm^2,积累率为26.2%-76.1%。与基础土比较,随着磷肥用量的增加,土壤有效磷、全磷、无机磷总量及无机磷中的Ca2-P、Ca8-P、Al-P、Fe-P含量均呈显著增加趋势,无机磷中的O-P、Ca10-P含量无显著变化。P2O5年用量为720、1080、1440 kg/hm^2处理土壤的有效磷年均增加量为2.3、4.2、5.0 mg/kg;土壤有效磷增加量与磷盈余量呈显著直线正相关关系,土壤磷素每盈余100 kg/hm^2,有效磷、Ca2-P、Ca8-P、Al-P、Fe-P含量分别增加1.13、2.41、15.27、4.14、1.37 mg/kg。随着土壤磷盈余量和施肥年限的增加,有效磷占全磷比重、Ca2-P、Ca8-P、Al-P占无机磷比重逐渐增加。【结论】施用磷肥显著增加大白菜和菜豆产量,过量施用磷肥蔬菜产量无显著变化;土壤磷素处于盈余状态下,随着磷肥用量的增加或种植年限的增加,土壤积累磷的有效性随之增加。基于蔬菜对磷肥产量响应和土壤磷素收支表观平衡状况,露地大白菜P2O5推荐用量180 kg/hm^2,菜豆270 kg/hm^2。 . 【目的】研究长期连续过量施用磷肥下蔬菜的产量响应、磷肥去向及土壤各形态磷库的动态变化。【方法】在太行山山前平原典型潮褐土上,连续进行11年21茬露地蔬菜的长期定位肥料试验,P2O5年施用量设0（P0）、360（P1）、720（P2）、1080（P3）、1440（P4）kg/hm^2共5个处理,分别测定每茬蔬菜产量及各年土壤不同形态磷素含量。【结果】与不施磷肥处理比较,单季P2O5用量180、360、540、720 kg/hm^2均显著增加大白菜、菜豆产量,不同磷肥用量间蔬菜产量均无显著差异。P2O5年用量为360、720、1080、1440 kg/hm^2,土壤年盈余磷为41.2-478.7 kg/hm^2,积累率为26.2%-76.1%。与基础土比较,随着磷肥用量的增加,土壤有效磷、全磷、无机磷总量及无机磷中的Ca2-P、Ca8-P、Al-P、Fe-P含量均呈显著增加趋势,无机磷中的O-P、Ca10-P含量无显著变化。P2O5年用量为720、1080、1440 kg/hm^2处理土壤的有效磷年均增加量为2.3、4.2、5.0 mg/kg;土壤有效磷增加量与磷盈余量呈显著直线正相关关系,土壤磷素每盈余100 kg/hm^2,有效磷、Ca2-P、Ca8-P、Al-P、Fe-P含量分别增加1.13、2.41、15.27、4.14、1.37 mg/kg。随着土壤磷盈余量和施肥年限的增加,有效磷占全磷比重、Ca2-P、Ca8-P、Al-P占无机磷比重逐渐增加。【结论】施用磷肥显著增加大白菜和菜豆产量,过量施用磷肥蔬菜产量无显著变化;土壤磷素处于盈余状态下,随着磷肥用量的增加或种植年限的增加,土壤积累磷的有效性随之增加。基于蔬菜对磷肥产量响应和土壤磷素收支表观平衡状况,露地大白菜P2O5推荐用量180 kg/hm^2,菜豆270 kg/hm^2。 |
| [25] | . 通过5年田间肥料定位试验，研究连续过量施用磷肥和有机肥在蔬菜上的产量效应，土壤积累磷在0—5, 0—10, 10—20, 20—80 cm土层的分布特点及农田积累磷的流失风险评价。结果表明，P<SUB>2</SUB>O<SUB>5</SUB>用量为180～360 kg/hm<SUP>2</SUP>，大白菜、伏白菜、辣椒、豆角的产量分别平均增加21.5%、39.5%、71.6%、50.0%；有机肥用量为150～300 t/hm<SUP>2</SUP>，4种蔬菜产量分别平均增加23.8%、26.7%、62.6%、80.0%，差异均达到显著和极显著水平。土壤Olsen-P 在蔬菜上的产量效应符合一元二次式。连续5年施用磷肥和有机肥，0—60 cm土壤各形态磷均显著积累；20—40、40—60、60—80 cm土壤Olsen-P分别相当于0—20 cm Olsen-P 的35.7%、11.8%、7.1%；0—20 cm 土壤Olsen-P分别相当于0—5、0—10 cm Olsen-P的 88.1%、84.0%。0—20 cm土壤Olsen-P与CaCl<SUB>2</SUB>-P、NaOH-P、灌溉滞留水中的可溶磷及农田磷流失风险势（P-index ）均呈显著正相关关系。石灰性土壤Olsen-P可作为评价农田磷生产力和环境风险评价的指标。 . 通过5年田间肥料定位试验，研究连续过量施用磷肥和有机肥在蔬菜上的产量效应，土壤积累磷在0—5, 0—10, 10—20, 20—80 cm土层的分布特点及农田积累磷的流失风险评价。结果表明，P<SUB>2</SUB>O<SUB>5</SUB>用量为180～360 kg/hm<SUP>2</SUP>，大白菜、伏白菜、辣椒、豆角的产量分别平均增加21.5%、39.5%、71.6%、50.0%；有机肥用量为150～300 t/hm<SUP>2</SUP>，4种蔬菜产量分别平均增加23.8%、26.7%、62.6%、80.0%，差异均达到显著和极显著水平。土壤Olsen-P 在蔬菜上的产量效应符合一元二次式。连续5年施用磷肥和有机肥，0—60 cm土壤各形态磷均显著积累；20—40、40—60、60—80 cm土壤Olsen-P分别相当于0—20 cm Olsen-P 的35.7%、11.8%、7.1%；0—20 cm 土壤Olsen-P分别相当于0—5、0—10 cm Olsen-P的 88.1%、84.0%。0—20 cm土壤Olsen-P与CaCl<SUB>2</SUB>-P、NaOH-P、灌溉滞留水中的可溶磷及农田磷流失风险势（P-index ）均呈显著正相关关系。石灰性土壤Olsen-P可作为评价农田磷生产力和环境风险评价的指标。 |
| [26] | . Studies have shown that yield responses of grass leys to phosphorus (P) fertilization vary considerably and initial soil test P (STP) does not always predict such variation. To identify the sources of variation in dry-matter (DM) yield responses to P, we used a meta-analysis to review quantitatively 38 Finnish field experiments on various soil types and growth conditions and to develop yield-response models. The major sources of variation in the yield responses to annually applied P were soil type, soil acidity (for organic soils), initial STP and control yields fertilized with nitrogen (N) and potassium (K). According to Mitscherlich-type exponential models, the maximum yield increases due to P fertilization in the low-STP class were 18% over the control on mineral soils and 28% on organic soils. However, only about 40% of the variation in yield could be attributed to annual fertilizer P applications. Control yields explained about 25% of variation in yield responses to P fertilization, and P addition became less efficient with increasing control yields, which were associated with rising N rates. While applied P leads to infrequent or small yield responses on mineral soils, other practices to increase grass yields should be prioritized, including optimal N fertilization. On moderately acidic organic soils that show clearly lower P responses than do similar but less acidic soils, liming should be the first step to increase yields. Moreover, the models derived in this work indicate that revising P fertilizer recommendations in Finland would avoid unnecessary application at non-responsive STP levels. |
| [27] | . <p>设置0、70、140、210和280 kg N·hm<sup>–2</sup> 5个施N梯度, 对冬小麦(<em>Triticum aestivum</em>)旗叶光合速率(<em>A</em><sub>leaf</sub>)、群体冠层光合速率(<em>A</em><sub>canopy</sub>)、作物生长速率(<em>CGR</em>)和籽粒产量(<em>GY</em>) 4个生产力水平进行综合观测研究, 结果发现: 在0–210 kg N·hm<sup>–2</sup>区间, <em>A</em><sub>leaf</sub>、<em>A</em><sub>canopy</sub>、<em>CGR</em>和<em>GY</em>都随施N量的增大而增大; 在施N量由210增加到280 kg N·hm<sup>–2</sup>时, <em>GY</em>没有显著变化, 而灌浆期<em>A</em><sub>leaf</sub>、开花期和灌浆期<em>A</em><sub>canopy</sub>、开花-成熟阶段<em>CGR</em>有显著减小。综合分析认为: 1)过量施N (280 kg N·hm<sup>–2</sup>)能显著降低灌浆期冬小麦</br><em>A</em><sub>leaf</sub>、<em>A</em><sub>canopy</sub>和<em>CGR</em>, 进而抑制<em>GY</em>; 2)过量施N对冬小麦光合生产力的抑制作用主要发生在灌浆期; 3)在<em>A</em><sub>leaf</sub>、<em>A</em><sub>canopy</sub>、<em>CGR</em>和<em>GY</em>4个生产力指标中, <em>A</em><sub>canopy</sub>对过量施N的反应最敏感。</p> . <p>设置0、70、140、210和280 kg N·hm<sup>–2</sup> 5个施N梯度, 对冬小麦(<em>Triticum aestivum</em>)旗叶光合速率(<em>A</em><sub>leaf</sub>)、群体冠层光合速率(<em>A</em><sub>canopy</sub>)、作物生长速率(<em>CGR</em>)和籽粒产量(<em>GY</em>) 4个生产力水平进行综合观测研究, 结果发现: 在0–210 kg N·hm<sup>–2</sup>区间, <em>A</em><sub>leaf</sub>、<em>A</em><sub>canopy</sub>、<em>CGR</em>和<em>GY</em>都随施N量的增大而增大; 在施N量由210增加到280 kg N·hm<sup>–2</sup>时, <em>GY</em>没有显著变化, 而灌浆期<em>A</em><sub>leaf</sub>、开花期和灌浆期<em>A</em><sub>canopy</sub>、开花-成熟阶段<em>CGR</em>有显著减小。综合分析认为: 1)过量施N (280 kg N·hm<sup>–2</sup>)能显著降低灌浆期冬小麦</br><em>A</em><sub>leaf</sub>、<em>A</em><sub>canopy</sub>和<em>CGR</em>, 进而抑制<em>GY</em>; 2)过量施N对冬小麦光合生产力的抑制作用主要发生在灌浆期; 3)在<em>A</em><sub>leaf</sub>、<em>A</em><sub>canopy</sub>、<em>CGR</em>和<em>GY</em>4个生产力指标中, <em>A</em><sub>canopy</sub>对过量施N的反应最敏感。</p> |
| [28] | . A long-term (1982-2001) field experiment was conducted on a calcareous soil at Zhangye, Gansu under wheat (Triticum aestivum L.)-wheat(Triticum aestivum L.)-corn (Zea mays L.) rotation system in order to determine the effects of long-term fertilization on crop yield, content and accumulation of nitrate-N in soil profiles. Twenty-four plots in a split-plot include eight treatments [nitrogen (N), phosphorus (P), potassium (K) and farmyard manure (M) application] and 3 replicates were designed. Main treatments were M and no M, and the sub-treatments were no-fertilizer (CK), N, NP and NPK. In P and K were part of treatments, their ratio to N was 1N﹕0.22P﹕0.42K. All M, P and K fertilizers were applied as the basal dressing. The crops were harvested for grain yield in all years and for straw yields from 1988 to 1997. After crop harvest in 2000, the soil was sampled from the 0-20, 20-60, 60-100, 100-140 and 140-180 cm depths to determine NO3--N content. The twenty-year grain yield decreased in the order of MNPK≥MNP＞NPK＞MN＞NP＞M＞N＞CK. Corn yield of CK in 2000 was only 28.2% of that in 1984, and wheat in 2001 was 25.7% of that in 1982. Average impact of fertilizers on grain yield decreased in the order of N＞M＞P＞K. Yield response to N and P fertilizers increased with progression of the experiment. K fertilizer showed no effects on increase of grain yield during the initial 6 years (1982-1987), moderate effects in the next 5 years (1988-1992), and dramatic effects in the last 9 years (1993-2001). The straw yield trend was similar to grain yield. Accumulation and distribution of NO3--N in soil was significantly affected by annual fertilizations. Chemical fertilizers (NP and NPK) caused NO3--N accumulation in most subsoil layers, with major impact in the 20-140 cm depth. The combination of chemical fertilizers and M (MNP and MNPK) reduced soil NO3--N accumulation as compared to chemical fertilizers alone. In conclusion, long-term fertilization significantly improved grain and straw yield in this rotation. The findings suggest that it is important to balance the application of chemical fertilizers and manure in order to protect soil and underground water from potential NO3--N pollution while keeping high productivity in the Oasis agro-ecosystem. . A long-term (1982-2001) field experiment was conducted on a calcareous soil at Zhangye, Gansu under wheat (Triticum aestivum L.)-wheat(Triticum aestivum L.)-corn (Zea mays L.) rotation system in order to determine the effects of long-term fertilization on crop yield, content and accumulation of nitrate-N in soil profiles. Twenty-four plots in a split-plot include eight treatments [nitrogen (N), phosphorus (P), potassium (K) and farmyard manure (M) application] and 3 replicates were designed. Main treatments were M and no M, and the sub-treatments were no-fertilizer (CK), N, NP and NPK. In P and K were part of treatments, their ratio to N was 1N﹕0.22P﹕0.42K. All M, P and K fertilizers were applied as the basal dressing. The crops were harvested for grain yield in all years and for straw yields from 1988 to 1997. After crop harvest in 2000, the soil was sampled from the 0-20, 20-60, 60-100, 100-140 and 140-180 cm depths to determine NO3--N content. The twenty-year grain yield decreased in the order of MNPK≥MNP＞NPK＞MN＞NP＞M＞N＞CK. Corn yield of CK in 2000 was only 28.2% of that in 1984, and wheat in 2001 was 25.7% of that in 1982. Average impact of fertilizers on grain yield decreased in the order of N＞M＞P＞K. Yield response to N and P fertilizers increased with progression of the experiment. K fertilizer showed no effects on increase of grain yield during the initial 6 years (1982-1987), moderate effects in the next 5 years (1988-1992), and dramatic effects in the last 9 years (1993-2001). The straw yield trend was similar to grain yield. Accumulation and distribution of NO3--N in soil was significantly affected by annual fertilizations. Chemical fertilizers (NP and NPK) caused NO3--N accumulation in most subsoil layers, with major impact in the 20-140 cm depth. The combination of chemical fertilizers and M (MNP and MNPK) reduced soil NO3--N accumulation as compared to chemical fertilizers alone. In conclusion, long-term fertilization significantly improved grain and straw yield in this rotation. The findings suggest that it is important to balance the application of chemical fertilizers and manure in order to protect soil and underground water from potential NO3--N pollution while keeping high productivity in the Oasis agro-ecosystem. |
| [29] | . 总结2006-2009年陕西省渭北旱塬测土配方施肥项目180个“3414”试验数据，分析当前生产条件下旱作区小麦施肥效果以及施肥量、 土壤肥力水平对小麦产量、 经济效益、 肥料利用效率等的影响，为提高旱作小麦产量和肥料高效利用提供依据。结果表明， 施用氮（N）、 磷（P2O5）、 钾肥（K2O）小麦分别增产986、 679和405 kg/hm2，增产率为30.0%、 18.9%和9.5%，增收1098、 810和392 Yuan/hm2，对小麦产量的贡献率分别为21.5%、 14.8%和8.8%，农学效率分别为6.4、 7.1和7.1 kg/kg; 施肥增产、 增收效果以及肥料贡献率均表现为N＞P2O5＞K2O，农学效率表现为P2O5＝K2O＞N; 与不施肥相比，平衡施用氮、 磷、 钾肥（N＋P2O5＋K2O）小麦增产73.0%，增收1923 Yuan/hm2，对产量的贡献率为40.0%，农学效率为5.8 kg/kg; 过量施用氮、 磷、 钾肥均无显著减产效应，推荐施肥处理化肥的增产、 增收效果， 对产量的贡献率以及农学效率均最高。土壤肥力对化肥肥效有显著影响，投肥于中、 低肥力土壤既能实现养分高效利用又能获得较大经济效益。与20世纪80年代相比，氮肥利用效率明显降低，磷肥肥效基本不变，而钾肥肥效在快速提升。合理施肥与耕作、 栽培等多种措施相结合是旱区作物增产、 增收的有效途径。 . 总结2006-2009年陕西省渭北旱塬测土配方施肥项目180个“3414”试验数据，分析当前生产条件下旱作区小麦施肥效果以及施肥量、 土壤肥力水平对小麦产量、 经济效益、 肥料利用效率等的影响，为提高旱作小麦产量和肥料高效利用提供依据。结果表明， 施用氮（N）、 磷（P2O5）、 钾肥（K2O）小麦分别增产986、 679和405 kg/hm2，增产率为30.0%、 18.9%和9.5%，增收1098、 810和392 Yuan/hm2，对小麦产量的贡献率分别为21.5%、 14.8%和8.8%，农学效率分别为6.4、 7.1和7.1 kg/kg; 施肥增产、 增收效果以及肥料贡献率均表现为N＞P2O5＞K2O，农学效率表现为P2O5＝K2O＞N; 与不施肥相比，平衡施用氮、 磷、 钾肥（N＋P2O5＋K2O）小麦增产73.0%，增收1923 Yuan/hm2，对产量的贡献率为40.0%，农学效率为5.8 kg/kg; 过量施用氮、 磷、 钾肥均无显著减产效应，推荐施肥处理化肥的增产、 增收效果， 对产量的贡献率以及农学效率均最高。土壤肥力对化肥肥效有显著影响，投肥于中、 低肥力土壤既能实现养分高效利用又能获得较大经济效益。与20世纪80年代相比，氮肥利用效率明显降低，磷肥肥效基本不变，而钾肥肥效在快速提升。合理施肥与耕作、 栽培等多种措施相结合是旱区作物增产、 增收的有效途径。 |
| [30] | . The continuous application of phosphorus (P) to agricultural systems to ensure profitable crop productivity can lead to an accumulation of P in agricultural soils. While this long-term residual pool... |
| [31] | . This study evaluated the impacts of three sugarcane residue management techniques, namely postharvest burning of residue (BR), shredding of residue (SR), and full postharvest retention of residue (RR), on the water quality of surface runoff from February 2006 to September 2007 in Iberia, LA. Total runoff volumes recorded were 58,418, 57,923, and 46,57802L for the BR, SR, and RR treatments, respectively. Except for total Kjeldahl nitrogen (TKN), which was higher for BR than RR or SR, there were no significant differences in total loads of total suspended solids (TSS), total dissolved solids (TDS), biological oxygen demand at 502days (BOD 5 ), total phosphorus (TP), nitrate-N, nitrite-N, and sulfate among the three residue management techniques, although the RR treatment generally exported the lowest total loads. Regression analyses on the pollutant load and rainfall event showed that the load exported for each water quality parameter was positively correlated with precipitation, with the BR treatment being more sensitive to rainfall amount than the RR and SR treatments in TSS, TKN, TP, BOD, nitrate, and sulfate exports. Runoff TSS and turbidity were also highly correlated ( R 2 65=650.95, P 65<650.001). The results suggested that the two sugarcane residue retention practices (RR and SR) had limited benefit on improving surface runoff water quality over the BR practice in subtropical region such as Louisiana. |
| [32] | . The role of detrital quantity and quality in forest floor N leaching was investigated in a litter manipulation experiment at a deciduous forest under chronic N deposition. Dissolved inorganic nitrogen (DIN) comprised the bulk of nitrogen leaching from the control except a short period following autumn litterfall. The dominance of DIN was strengthened by litter exclusion, whereas the addition of glucose or fresh litter led to a small increase in dissolved organic nitrogen (DON) and either a temporary or gradual reduction in NO 3 鈭 release, respectively. Changes in soluble organic C and microbial C in the forest floor implied that increased availability of C sources might have enhanced microbial immobilization of DIN, either temporarily following glucose application or over the longer term following litter addition. The results suggest that detrital quantity and quality can play a crucial role in determining the balance between DIN and DON in N-enriched forest soils. |
