張 濤李素艷孫向陽(yáng)王振宇張 洋張 樂(lè)龔小強(qiáng)趙秀芳謝志遠(yuǎn)宋國(guó)香
(1 北京林業(yè)大學(xué)林學(xué)院,北京 100083)
(2 天津泰達(dá)鹽堿地綠化研究中心有限公司,天津 300457)
磷石膏、紅糖等對(duì)蚯蚓改良濱海鹽土的促進(jìn)作用*
張 濤1,2李素艷1?孫向陽(yáng)1王振宇2張 洋1張 樂(lè)1龔小強(qiáng)1趙秀芳2謝志遠(yuǎn)2宋國(guó)香2
(1 北京林業(yè)大學(xué)林學(xué)院,北京 100083)
(2 天津泰達(dá)鹽堿地綠化研究中心有限公司,天津 300457)
前期研究表明,施入園林廢棄物作為餌料并投放蚯蚓能夠降低濱海鹽土鹽分。通過(guò)田間對(duì)比試驗(yàn),研究同時(shí)添加磷石膏和紅糖對(duì)蚯蚓改良濱海鹽土的促進(jìn)作用。結(jié)果表明,在每平方米施入6.5 kg園林廢棄物及50條蚯蚓(平均質(zhì)量0.334 g)的基礎(chǔ)上,添加磷石膏能夠顯著降低土壤pH以及水溶性鈉離子(Na+)和氯離子(Cl-)的含量,但同時(shí)會(huì)顯著增加土壤水溶性鈣離子(Ca2+)及硫酸根離子(SO42-)含量;隨著磷石膏施入量的提高,土壤全鹽量呈現(xiàn)先降低后升高的趨勢(shì)。添加紅糖能夠間接降低鹽堿土壤水溶性Na+和Cl-的含量以及全鹽量,但不同紅糖施入量的處理間并無(wú)顯著差異。根據(jù)試驗(yàn)結(jié)果,推薦在施入園林廢棄物作為餌料并投放蚯蚓的基礎(chǔ)上,同時(shí)添加1 kg m-2的磷石膏及0.4 kg m-2的紅糖,以取得最佳的降鹽效果。
濱海鹽土改良;蚯蚓;園林廢棄物;磷石膏
隨著我國(guó)經(jīng)濟(jì)和社會(huì)的快速發(fā)展,沿海城市濱海鹽土的綠化改良成為亟待解決的問(wèn)題。我國(guó)濱海地區(qū)鹽堿地約有1.3×105km2[1],由于該區(qū)域地下水礦化度高、埋藏深度較淺,且年蒸發(fā)量高于年降雨量,容易導(dǎo)致土壤的鹽堿化[2]。鹽堿土壤的生物改良方法具有成本低、效果好、無(wú)污染的優(yōu)點(diǎn),但多局限于種植耐鹽植物[3-5],采用土壤動(dòng)物改良的方法研究較少。在改良鹽堿土壤的過(guò)程中,接種蚯蚓有利于鞏固鹽堿地改良效果,促進(jìn)鹽堿地持續(xù)利用[6]。據(jù)調(diào)查,蚯蚓可以在全鹽量達(dá)到11.47 g kg-1的鹽堿土中生存,優(yōu)勢(shì)種為赤子愛(ài)勝蚓(Eisenia fetida)[7-8]。該蚯蚓品種適應(yīng)性較強(qiáng),自然分布于包括河北省在內(nèi)的我國(guó)15個(gè)省及直轄市[9],在野外應(yīng)用時(shí)可最大限度地避免由于蚯蚓入侵而可能導(dǎo)致的負(fù)面影響[10]。此外,赤子愛(ài)勝蚓是我國(guó)蚯蚓養(yǎng)殖的主要品種(商品名大平2號(hào)[11]),來(lái)源豐富,利于推廣。前期研究表明,以經(jīng)過(guò)腐熟發(fā)酵的園林廢棄物作為餌料的條件下,投放蚯蚓能夠降低濱海鹽土鹽分[12]。
園林廢棄物是城市園林綠化過(guò)程中大量產(chǎn)出的有機(jī)綠化垃圾[13],其消納處理是一項(xiàng)亟需解決的問(wèn)題。在園林廢棄物中添加一定的糖分能夠促進(jìn)蚯蚓活動(dòng)[14],提高蚯蚓對(duì)鹽堿土壤環(huán)境的適應(yīng)性,并加速有機(jī)物質(zhì)的分解轉(zhuǎn)化,改良鹽堿土壤。磷石膏是磷酸工業(yè)廢渣,年產(chǎn)量極高,大量堆積會(huì)對(duì)自然環(huán)境造成極大的污染。作為傳統(tǒng)鹽堿土壤改良劑[15],磷石膏能夠降低土壤鹽分及pH[16-17],促進(jìn)植物生長(zhǎng)[18-19],為蚯蚓生存提供有利條件。本文以河北省臨港經(jīng)濟(jì)技術(shù)開發(fā)區(qū)的濱海鹽土為研究對(duì)象,探討了在添加園林廢棄物以及投放蚯蚓的前提下,同時(shí)添加磷石膏和紅糖對(duì)蚯蚓改良濱海鹽土的促進(jìn)作用。
1.1 研究區(qū)概況
研究區(qū)位于滄州臨港經(jīng)濟(jì)技術(shù)開發(fā)區(qū),屬暖溫帶半濕潤(rùn)大陸性季風(fēng)氣候,年平均氣溫12.1℃,1月平均氣溫-4.4℃,7月平均氣溫26.4℃,無(wú)霜期210 d。年平均降水量627 mm(其中75%集中在夏季),蒸發(fā)量為降雨量的3倍多,加之地下水礦化度大(約為4 g L-1),埋藏深度較淺(雨季地下水深度80 cm),極易造成土壤鹽漬化。
試驗(yàn)地位于滄州臨港經(jīng)濟(jì)技術(shù)開發(fā)區(qū)學(xué)院路南側(cè)綠化帶(38°23′ N,117°26′ E,海拔高度2 m),綠化施工時(shí)采取客土抬高地面的工程措施,用客土將試驗(yàn)地抬高約0.8 m,但未采取任何隔鹽或排鹽措施;試驗(yàn)于客土約半年后進(jìn)行。所用綠化喬木主要有白蠟(Fraxinus chinensis)、國(guó)槐(Sophora japonica)、旱柳(Salix matsudana)和毛泡桐(Paulownia tomentosa)等。試驗(yàn)區(qū)原貌地土壤及綠化客土均為砂壤質(zhì)典型濱海鹽土,其理化性質(zhì)如表1所示,各土壤取樣點(diǎn)均未發(fā)現(xiàn)蚯蚓活動(dòng)痕跡。
1.2 供試材料
試驗(yàn)用磷石膏購(gòu)自山東省泰安市華鎣商貿(mào)有限公司,其pH約為2.5,主要成分為CaSO4·2H2O(占總質(zhì)量的94.6%);試驗(yàn)用紅糖購(gòu)自當(dāng)?shù)毓╀N合作聯(lián)合社。試驗(yàn)用園林廢棄物(Composted green waste,CGW)取自北京市朝陽(yáng)區(qū)園林綠化廢棄物消納中心,具體堆制過(guò)程參見(jiàn)Zhang等[20]的二階段堆肥方法。供試園林廢棄物理化性質(zhì)如表1所示。
試驗(yàn)用蚯蚓(E. fetida)購(gòu)自北京市順義區(qū)大環(huán)順鑫有機(jī)肥料廠,購(gòu)回后將蚯蚓置于裝有鹽堿土壤的塑料桶中,并在表面覆蓋1 cm厚的園林廢棄物;保持桶內(nèi)物料濕度在25%(±1%,W/W)左右并保持涼爽,以使蚯蚓適應(yīng)試驗(yàn)環(huán)境。待蚯蚓適應(yīng)試驗(yàn)環(huán)境約1個(gè)月后,選取環(huán)帶清晰,反應(yīng)靈敏,個(gè)體大小與體重基本相同的蚯蚓進(jìn)行試驗(yàn)。
表1 試驗(yàn)區(qū)土壤及園林廢棄物理化性質(zhì)Table 1 Physico-chemical properties of the saline soil in the experiment field site and the composted green waste applied to the saline soil
1.3 試驗(yàn)設(shè)計(jì)
試驗(yàn)于試驗(yàn)地鹽堿水平相同的區(qū)域進(jìn)行,共設(shè)置2個(gè)因素,分別為磷石膏(Phosphogypsum,Pg)和紅糖(Brown sugar,BS);每個(gè)因素設(shè)置4個(gè)水平,其中磷石膏施用量為0 kg m-2、1 kg m-2、2 kg m-2、3 kg m-2(即Pg-0、Pg-1、Pg-2、Pg-3),紅糖施用量為0 kg m-2、0.2 kg m-2、0.4 kg m-2、0.6 kg m-2(即BS-0、BS-0.2、BS-0.4、BS-0.6);各因素的不同水平間兩兩組合,共計(jì)16個(gè)處理,其中Pg-0、BS-0處理組合為只添加園林廢棄物并投放蚯蚓,而未添加磷石膏或紅糖的處理。各處理在試驗(yàn)區(qū)內(nèi)隨機(jī)分布,每個(gè)處理小區(qū)面積為12 m2,包含3棵毛泡桐(P. tomentosa),試驗(yàn)重復(fù)3次。根據(jù)前期試驗(yàn)的結(jié)果,各處理均添加6.5 kg m-2的園林廢棄物及50 條 m-2(約16.7 g)的蚯蚓[12]。磷石膏按照不同處理要求的用量直接撒入土壤;紅糖按不同處理要求的用量,用水溶解后摻入園林廢棄物中混勻,再撒入土壤。由于蚯蚓對(duì)土壤改良的效果集中在土壤表層[21],故在本試驗(yàn)中將施入的磷石膏及摻有紅糖的園林廢棄物與0~20 cm的表層土壤攪拌混勻。雖然試驗(yàn)所用蚯蚓僅對(duì)表層土壤產(chǎn)生作用,但由于鹽堿土壤鹽分也多聚積在土壤表層[22-23],因此采取蚯蚓改良鹽堿土壤仍具有積極意義。
為防止磷石膏酸性過(guò)強(qiáng)毒害蚯蚓,磷石膏于2014年6月施入土壤,蚯蚓隨摻有紅糖的園林廢棄物于1個(gè)月后投放于土壤中;該1個(gè)月時(shí)間用于前文提到的蚯蚓適應(yīng)試驗(yàn)環(huán)境的過(guò)程。此外,保留未進(jìn)行任何處理,僅對(duì)0~20 cm表層土壤進(jìn)行攪拌混勻的區(qū)域作為對(duì)照(CK)。試驗(yàn)期間,各處理采取相同的養(yǎng)護(hù)措施。
1.4 樣品采集與分析
土壤樣品于2015年7月進(jìn)行采集,于每個(gè)處理中隨機(jī)選取3個(gè)點(diǎn)采集表層土壤(0~20 cm)。由于大田試驗(yàn)條件限制,試驗(yàn)結(jié)束后各處理的蚯蚓數(shù)目未進(jìn)行統(tǒng)計(jì),但在取樣時(shí)各處理均可發(fā)現(xiàn)存活的蚯蚓或新鮮的蚯蚓糞,說(shuō)明蚯蚓能夠適應(yīng)試驗(yàn)地條件并自然越冬。
采回的土壤樣品經(jīng)自然風(fēng)干后,碾碎過(guò)篩(1 mm),并以水土比5∶1制備土壤水溶液以進(jìn)行指標(biāo)測(cè)定。其中,土壤pH使用通用型pH計(jì)(OHAUS Starter 3C,美國(guó))測(cè)定;土壤的水溶性鹽分離子中,碳酸根離子(CO32-)和碳酸氫根離子(HCO3-)采用雙指示劑—中和滴定法測(cè)定;氯離子(Cl-)采用硝酸銀滴定法(莫爾法)測(cè)定;鈣離子(Ca2+)和鎂離子(Mg2+)采用乙二胺四乙酸(EDTA)滴定法測(cè)定;硫酸根離子(SO42-)采用EDTA間接絡(luò)合滴定法測(cè)定;鉀離子(K+)和鈉離子(Na+)采用火焰光度法測(cè)定;全鹽量為上述八種離子含量之和[24]。
1.5 數(shù)據(jù)處理
全部數(shù)據(jù)采用Excel 2010及SPSS 18進(jìn)行統(tǒng)計(jì)分析。采用單因素方差分析(one-way ANOVA)比較不同處理間的差異;多重比較采用鄧肯(Duncan)法檢驗(yàn)在方差分析中有差異的變量間的差異顯著性。
2.1 蚯蚓與改良劑施入后土壤pH變化
在施入園林廢棄物并投放蚯蚓的基礎(chǔ)上,添加磷石膏能夠有效降低鹽堿土壤的pH,如圖1所示。與未施入磷石膏的處理(Pg-0)相比,施入磷石膏能夠顯著降低土壤的pH,但不同磷石膏用量的處理間無(wú)顯著差異。磷石膏能夠降低鹽堿土壤pH的結(jié)果與劉易等[17]的研究相符,這可能由兩個(gè)原因造成:首先,磷石膏是在制取磷肥時(shí)用硫酸處理磷礦而產(chǎn)生的固體廢渣,有部分硫酸殘留,使得磷石膏本身pH較低(本試驗(yàn)中所用磷石膏pH約為2.5),這能夠直接影響到鹽堿土壤的pH;其次,磷石膏中的CaSO4與土壤溶液中HCO3-和CO32-反應(yīng)生成Ca(HCO3)2和難溶性的CaCO3,以及溶解度小于NaCl的Na2SO4[25],從而固定HCO3-和CO32-并促進(jìn)Na+的淋洗,間接降低土壤的pH[26]。而不同磷石膏用量的處理間無(wú)顯著差異,可能是由于土壤本身具有一定的緩沖性造成的。
本試驗(yàn)中,施入紅糖對(duì)蚯蚓活動(dòng)的促進(jìn)作用并未間接改變鹽堿土壤的pH。雖然蚯蚓活動(dòng)能夠改善土壤pH,使之趨向于中性[27],但其主要是依靠蚯蚓糞中具有一定酸性和緩沖性的腐殖酸類物質(zhì)對(duì)土壤pH進(jìn)行調(diào)節(jié)[28],因此,短時(shí)間內(nèi)難以產(chǎn)生顯著影響。
試驗(yàn)結(jié)果表明,施用磷石膏能夠顯著降低濱海鹽堿土壤的pH,但當(dāng)磷石膏的用量大于1 kg m-2(Pg-1)時(shí),其對(duì)鹽堿土壤pH的降低作用不再顯著。因此,綜合考慮磷石膏本身較高的鹽分和較低的pH對(duì)園林綠化植物可能產(chǎn)生的負(fù)面作用,以及降低改良成本的目的,推薦采用1 kg m-2的用量進(jìn)行改良。
2.2 蚯蚓與改良劑施入后土壤Ca2+及SO24-含量變化
由于磷石膏中的主要成分為CaSO4,因此土壤中的Ca2+及SO42-含量均隨磷石膏施入量的增加而增加,如圖2所示;施入紅糖對(duì)Ca2+及SO42-含量無(wú)顯著影響。土壤中增加的Ca2+能夠代換土壤膠體上的Na+,形成鈣膠體,從而促進(jìn)土壤團(tuán)粒結(jié)構(gòu)的形成,加速土壤鹽分自然淋洗的過(guò)程[29],有利于鹽堿土壤的改良。應(yīng)注意的是,SO42-含量基本隨Ca2+含量同步增長(zhǎng);雖然SO24-對(duì)植物的毒害作用低于Cl-,但其含量過(guò)高時(shí)仍會(huì)對(duì)植物產(chǎn)生鹽脅迫(中國(guó)內(nèi)陸的鹽堿土類型多為硫酸鹽型),造成危害。因此,磷石膏的施入量不宜過(guò)高。
圖1 不同處理土壤pH變化Fig 1 pH of the soil as affected by treatment
2.3 蚯蚓與改良劑施入后土壤Na+及Cl-含量變化
在未施入磷石膏的處理中(Pg-0),隨著紅糖添加量的提高,表層土壤(0~20 cm)中的Na+含量顯著降低;而在施入磷石膏的處理中,添加紅糖雖然能夠顯著降低表層土壤Na+含量,但不隨紅糖添加量的提高而改變(圖3)。Cl-含量變化與Na+相類似,在未施入磷石膏的處理中,添加紅糖能夠顯著降低表層土壤中的Cl-含量;隨著磷石膏施入量的提高,添加紅糖對(duì)Cl-含量的降低作用趨于不顯著(圖3)。
圖2 不同處理土壤Ca2+及SO24-含量變化Fig 2 Ca2+and SO24-contents in the soil as affected by treatment
添加紅糖可以降低表層鹽堿土壤Na+及Cl-含量的原因,可以歸結(jié)為蚯蚓活動(dòng)以及微生物活性提高的影響。由于蚯蚓喜食富含糖分的有機(jī)物質(zhì)[30],在餌料(即園林廢棄物)中添加紅糖可以促進(jìn)蚯蚓活動(dòng),增加土壤中由于蚯蚓活動(dòng)而產(chǎn)生的孔洞以及具有一定水穩(wěn)性的團(tuán)粒狀蚯蚓糞,從而改善土壤物理性質(zhì),加強(qiáng)了土壤鹽分自然淋洗的過(guò)程[31];蚯蚓活動(dòng)還能夠打斷土壤毛細(xì)管通路,切斷土層之間水吸力的連貫性,從而能夠緩解表層土壤的鹽分積累程度。此外,蚯蚓能夠加速園林廢棄物的分解,將其轉(zhuǎn)化為具有較高陽(yáng)離子吸附能力的腐殖酸類物質(zhì)[32],并與Ca2+結(jié)合為較為穩(wěn)定的腐殖酸鈣,促進(jìn)土壤團(tuán)粒結(jié)構(gòu)的生成[33],從而間接促進(jìn)了土壤鹽分自然淋洗的過(guò)程;蚯蚓活動(dòng)還能夠提高鹽堿土壤微生物數(shù)量[34],促進(jìn)土壤微生物群落的年輕化[35],提高土壤微生物活性[36],而添加紅糖本身也可以提高微生物的活性,加速園林廢棄物的腐熟分解[20],從而促進(jìn)了腐殖酸類物質(zhì)的形成,增強(qiáng)了鹽堿土壤的改良效果。
圖3 不同處理土壤Na+及Cl-含量變化Fig 3 Na+and Cl-contents in the soil as affected by treatment
隨著磷石膏施入量的提高,一方面,其自身所含的鹽分以及較強(qiáng)的酸性,可能會(huì)對(duì)蚯蚓以及土壤微生物群落產(chǎn)生越來(lái)越大的毒害作用,降低蚯蚓以及土壤微生物的活性,從而減弱了其對(duì)鹽堿土壤的改良作用;另一方面,前文提到磷石膏中的Ca2+能夠?qū)a+從土壤膠體上代換出來(lái),生成鈣膠體并促進(jìn)土壤團(tuán)聚體的形成,改善土壤物理性質(zhì),在加強(qiáng)土壤鹽分自然淋洗作用的同時(shí)抑制表層土壤返鹽,從而降低土壤中Na+及Cl-的含量,減小了不同紅糖添加量處理間的差距,對(duì)方差分析的結(jié)果產(chǎn)生影響。因此,隨著磷石膏施入量的提高,添加紅糖降低Na+及Cl-含量的效果趨于不顯著。
2.4 蚯蚓與改良劑施入后土壤全鹽量變化
與Na+及Cl-含量類似,在施入園林廢棄物并投放蚯蚓的基礎(chǔ)上,未施入磷石膏的處理(Pg-0)隨著紅糖施入量的提高,表層土壤全鹽量顯著下降;而在施入磷石膏的處理中,隨著磷石膏施入量的提高,施入紅糖對(duì)表層土壤全鹽量的降低作用趨向不顯著,尤其是Pg-2和Pg-3處理,施入紅糖未對(duì)土壤鹽分造成顯著影響(圖4)。造成該結(jié)果的原因可能有兩點(diǎn),首先,由于施入過(guò)多磷石膏抑制了蚯蚓活動(dòng),從而降低了其對(duì)鹽堿土壤的改良作用;其次,隨著磷石膏施入量的提高而引入的大量Ca2+及SO42-會(huì)對(duì)表層土壤全鹽量產(chǎn)生顯著影響,而蚯蚓活動(dòng)并不能抑制施入磷石膏造成的Ca2+及SO42-含量的提高,因此可能會(huì)對(duì)表層土壤全鹽量方差分析的結(jié)果產(chǎn)生影響。
雖然前人大量研究均發(fā)現(xiàn)磷石膏能夠降低土壤全鹽量[37-39],但并未提及磷石膏施入量高于一定程度后,土壤全鹽量會(huì)發(fā)生反彈。當(dāng)磷石膏施入量為1 kg m-2時(shí)(Pg-1),表層土壤全鹽量與未施入磷石膏的處理(Pg-0)相比有顯著的降低;隨著磷石膏施入量的提高,表層土壤全鹽量有回升的趨勢(shì),尤其是紅糖施入量為0.4 kg m-2和0.6 kg m-2的處理(BS-0.4、BS-0.6);當(dāng)磷石膏施入量達(dá)到3 kg m-2時(shí)(Pg-3),表層土壤全鹽量反而顯著高于未施入磷石膏的處理(Pg-0),這是由于施入紅糖可促進(jìn)蚯蚓以及微生物對(duì)鹽堿土壤的改良作用,使未施入磷石膏的處理(Pg-0)全鹽量降低造成的。雖然表層土壤中的Na+及Cl-的含量隨著磷石膏施入量的提高而減?。▓D3),但Ca2+及SO42-含量會(huì)提高(圖2),因此,表層土壤全鹽量發(fā)生反彈的結(jié)果是很容易發(fā)生的。
結(jié)合施入磷石膏及紅糖對(duì)鹽堿土壤的pH、Ca2+、SO24-、Na+和Cl-含量的影響(各處理對(duì)土壤中其他離子的影響較?。约叭}量等因素,建議磷石膏采取1 kg m-2的施用量(Pg-1);此時(shí)為獲得更顯著的改良效果,紅糖采取0.4 kg m-2的施用量(BS-0.4)。
圖4 不同處理土壤全鹽量變化Fig 4 Content of total salt in the soil as affected by treatment
2.5 改良效果及成本
如圖5所示,與同期未采取任何措施的對(duì)照處理(CK)相比,僅添加園林廢棄物作為餌料并投放蚯蚓、而未添加磷石膏或紅糖的措施(Pg-0、BS-0處理組合,T0)可以在一定程度上減緩?fù)寥赖拇紊}漬化,防止其退化至原貌地(Original soil,OS)的土壤鹽分水平;而采取上述推薦用量的措施(Pg-1、BS-0.4處理組合,Tbest)能夠進(jìn)一步抑制土壤的次生鹽漬化,促使表層土壤鹽分保持在與綠化客土(Alien soil for greening,AS)相近的水平,此時(shí)土壤改良成本約為每平方米10.60元(表2)。
圖5 不同處理對(duì)濱海鹽土改良效果Fig 5 Amelioration effects of saline soil as affected by treatment
表2 推薦措施下的土壤改良成本Table 2 Cost of saline soil amelioration using the recommended measures
試驗(yàn)結(jié)果表明,若不采取一定措施,回填的客土?xí)芸焱嘶蔀辂}化土壤,造成大量直接或間接的經(jīng)濟(jì)損失,如重新更換客土、補(bǔ)植苗木的材料費(fèi)及其產(chǎn)生的運(yùn)輸、人工費(fèi)用等。本研究推薦的土壤改良方式成本較低(目前常用的布設(shè)排鹽暗管等工程改良措施,施工成本約為每平方米70元),且配合栽植綠化植物,其產(chǎn)生的枯落物可為蚯蚓持續(xù)提供餌料,無(wú)需后續(xù)投入;而蚯蚓對(duì)土壤的改良作用會(huì)促進(jìn)植物生長(zhǎng),從而產(chǎn)生更多的枯落物為蚯蚓提供餌料,形成良性循環(huán)。在條件允許的情況下,若園林廢棄物能夠就地取材進(jìn)行堆制,則可進(jìn)一步降低土壤改良成本;此外,本方案中的紅糖可以采用制糖工業(yè)的副產(chǎn)品代替,如甜菜渣(1 920 Yuan t-1)、甘蔗渣(700 Yuan t-1)、糖蜜(1 200 Yuan t-1)等,也可降低改良成本。
本研究提出了一項(xiàng)采用廢棄資源改良濱海鹽堿土壤的方法,即在向每平方米土壤中添加6.5 kg園林廢棄物作為餌料并投放50條蚯蚓的基礎(chǔ)上,額外施用1 kg m-2的磷石膏和0.4 kg m-2的紅糖,以進(jìn)一步抑制表層土壤的返鹽,鞏固濱海鹽土改良效果,降低土壤次生鹽漬化造成的損失。與常見(jiàn)的工程改良措施相比,該改良方法成本較低,利于推廣,并具有一定的可持續(xù)性。此外,本改良方法為磷石膏及園林廢棄物的資源化再利用提供了可行的方案,利于循環(huán)經(jīng)濟(jì)的發(fā)展。在后期研究中,還可以考慮使用制糖工業(yè)的副產(chǎn)品代替本方案中的紅糖,可進(jìn)一步降低改良成本并提高廢棄資源的利用率。
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Effect of Amendments of Phosphogypsum and Brown Sugar on Earthworms Ameliorating Coastal Saline Soil
ZHANG Tao1,2LI Suyan1?SUN Xiangyang1WANG Zhenyu2ZHANG Yang1ZHANG Le1GONG Xiaoqiang1ZHAO Xiufang2XIE Zhiyuan2SONG Guoxiang2
(1 College of Forestry,Beijing Forestry University,Beijing 100083,China)
(2 Tianjin TEDA Saline Green Research Center Co.,Ltd.,Tianjin 300457,China)
【Objective】Coastal soils in North China are extremely susceptible to salinization because of the geographical and meteorological conditions of these areas. Nowadays,soil bioremediation has proved to be an effective and economical way to ameliorate saline soils and hence been extensively applied. However,researches in this aspect are mostly focused on phytoremediation by planting salt-tolerant plants,and little has been done on use of earthworms or other soil animals. The first phase of this study demonstrates that the introduction of earthworms Eisenia fetida using composted green waste as its food source could help lower salinity of the coastal saline soil in North China. 【Method】 In order to improve the efficiency of using E. fetida and composted green waste to ameliorate saline soil,a field experiment was conducted on addition of phosphogypsum,the conventional soil amendment,and brown sugar in an attempt to determine whether they may help improve the efficiency of the bioremediation. The experimental site was located on a tract of typical coastal saline soil in the Lingang Economic and Technological Development Zone of Cangzhou,Hebei,China. The field was divided into plots. Each plot,covering an area of 12 m2,was amended with 6.5 kg m-2of composted green waste and earthworms at 50 individuals per m2(average weight 0.334 g). In addition,the plots were applied with 0 kg m-2,1 kg m-2,2 kg m-2,or 3 kg m-2of phosphogypsum,along with 0 kg m-2,0.2 kg m-2,0.4 kg m-2,or 0.6 kg m-2of brown sugar,separately. 【Result】 The experiment went on forone year,with results showing that the addition of phosphogypsum could significantly decrease pH of the soil in the treatments applied with the same rate of brown sugar,however,the effect did not vary much with the amendment rate of phosphogypsum. As Ca2+and SO42-are the major component of phosphogypsum,application of the substance significantly increased the content of soluble Ca2+and SO24-in the soils the same in brown sugar treatment. The Ca2+in phosphogypsum helped formation of soil structure and promoted desalination of the saline soil,while reducing the content of soluble Na+and Cl-significantly;the amendment of brown sugar stimulated activities of the earthworms,thus facilitating formation of soil aggregates and hence leaching of salts,and eventually intensifying the effect of bioremediation. So in the treatments the same in phosphogypsum amendment rate,addition of brown sugar significantly lowered the content of soluble Na+and Cl-in the soil. As affected by the contents of soluble Ca2+,SO24-,Na+and Cl-in the soil,in the treatments amended with 0 kg m-2or 1 kg m-2of phosphogypsum,addition of brown sugar significantly lowered the content of total salt,but the effect did not vary with its amendment rate;however,in the treatments the same in the amendment rate of brown sugar,the content of total salt in the soil increased rather than decreased if too much phosphogypsum was used. 【Conclusion】 Aiming at lowering the content of total salt,it is recommended that in addition to 6.5 kg m-2of composted green waste and 50 individuals per m2of E. fetida,1 kg m-2of phosphogypsum and 0.4 kg m-2of brown sugar should be amended in bioremediation of the coastal saline soil in North China. Compared with CK(nothing amended),the amendment of composted green waste and E. fetida significantly decreased the content of total salt,and the effect was further enhanced when phosphogypsum and brown sugar was added at a recommended rate. The cost of soil amelioration with the above-described method is only 10.60 Yuan per m2,and it would be lowered if brown sugar is replaced by some by-products from the sugar industry,such as beet pulp,bagasse,and molasses.
Coastal saline soil amelioration;Earthworm;Composted green waste;Phosphogypsum
S156.4+2
A
10.11766/trxb201603170607
(責(zé)任編輯:陳榮府)
* 公益性行業(yè)(林業(yè))科研專項(xiàng)經(jīng)費(fèi)項(xiàng)目(201504205)和北京市教育委員會(huì)科學(xué)研究與研究生培養(yǎng)共建項(xiàng)目(BLCXY201603,BLCXY201604)共同資助 Supported by the Special Fund for Forest Scientific Research in the Public Welfare (No. 201504205)and the Graduate Training and Development Program of Beijing Municipal Commission of Education of China (Nos. BLCXY201603 and BLCXY201604)
? 通訊作者 Corresponding author,E-mail:lisuyan@bjfu.edu.cn
張 濤(1988―),男,天津人,博士,主要從事濱海鹽土改良研究。E-mail:zhangtao5291@126.com
2016-03-17;
2016-09-22;優(yōu)先數(shù)字出版日期(www.cnki.net):2016-10-17