劉小京

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環(huán)渤海缺水區(qū)鹽堿地改良利用技術(shù)研究*

劉小京

(中國(guó)科學(xué)院遺傳與發(fā)育生物學(xué)研究所農(nóng)業(yè)資源研究中心/中國(guó)科學(xué)院農(nóng)業(yè)水資源重點(diǎn)實(shí)驗(yàn)室/河北省節(jié)水農(nóng)業(yè)重點(diǎn)實(shí)驗(yàn)室 石家莊 050022)

針對(duì)淡水資源匱乏制約鹽堿地改良利用難題, 自1982年以來, 中國(guó)科學(xué)院遺傳與發(fā)育生物學(xué)研究所農(nóng)業(yè)資源研究中心在環(huán)渤海低平原和濱海平原開展了缺水鹽漬區(qū)鹽堿地改良利用研究與示范工作, 取得了以下研究成果: 1)研究明確了低平原缺水鹽漬區(qū)鹽堿地改良的淺層地下水埋深調(diào)控深度, 建立了井灌代排、蓄雨淋鹽的鹽堿地改良技術(shù)模式; 2)揭示了咸水結(jié)冰融水咸淡水分離在濱海鹽土的入滲規(guī)律, 發(fā)明了冬季咸水結(jié)冰灌溉改良濱海重鹽堿地技術(shù); 3)提出了耦合鹽堿區(qū)土壤水鹽運(yùn)移-氣候條件-植物生長(zhǎng)發(fā)育規(guī)律的鹽堿地改良思路, 建立了微域降鹽、秸稈隔鹽的鹽堿地農(nóng)藝改良技術(shù)模式; 4)探討了鹽生植物適應(yīng)鹽漬環(huán)境的機(jī)理, 建立了濱海鹽堿地鹽漬資源高效利用技術(shù)模式。形成了以咸水、雨水、耐鹽植物高效利用為核心的工程措施、農(nóng)藝措施與生物措施相結(jié)合的鹽堿地改良利用技術(shù)體系, 為環(huán)渤海缺水鹽漬區(qū)農(nóng)業(yè)發(fā)展和生態(tài)環(huán)境建設(shè)提供了科技支撐。

環(huán)渤海; 缺水; 鹽堿地; 井灌代排; 微域降鹽; 咸水灌溉; 鹽生植物

鹽堿土是一系列受鹽堿作用的土壤, 是各種鹽土、堿土以及其他不同程度鹽化和堿化的各種類型土壤的統(tǒng)稱。全世界鹽堿土面積約為9.5億hm2, 我國(guó)鹽堿土面積約為9 913萬hm2(其中現(xiàn)代鹽堿土約3 693萬hm2), 主要分布于干旱、半干旱地帶和濱海地區(qū)[1]。鹽堿土由于含有過量的鹽分離子, 影響植物的生長(zhǎng), 甚至不能成活, 導(dǎo)致鹽堿區(qū)生物生產(chǎn)力低下, 生態(tài)環(huán)境較差。隨著人口增加、耕地減少, 作為重要的土地資源, 鹽堿土的改良利用越來越為重要, 對(duì)保障糧食安全和滿足人們對(duì)美好生活的需求具有重要的意義。

為改良利用鹽堿地, 1982年在河北省政府和中國(guó)科學(xué)院支持下, 中國(guó)科學(xué)院遺傳與發(fā)育生物學(xué)研究所農(nóng)業(yè)資源研究中心(原中國(guó)科學(xué)院石家莊農(nóng)業(yè)現(xiàn)代化研究所, 以下簡(jiǎn)稱“農(nóng)業(yè)資源研究中心”)的科研人員在河北省滄州市南皮縣建立了鹽堿地綜合治理試驗(yàn)區(qū), 開展農(nóng)業(yè)綜合發(fā)展研究和中低產(chǎn)田治理工作, 之后承擔(dān)了國(guó)家、中國(guó)科學(xué)院和河北省“七五”—“九五”的黃淮海平原綜合治理南皮近濱海缺水鹽漬區(qū)綜合治理科技攻關(guān)任務(wù), 中日合作“提高黃淮海平原鹽堿地生物生產(chǎn)力技術(shù)開發(fā)”(1991—1999年), 形成了井灌條件下以淺層地下水調(diào)控為核心、農(nóng)藝技術(shù)和生物技術(shù)相結(jié)合的鹽堿地治理模式, 相關(guān)治理成果“南皮近濱海缺水鹽漬區(qū)綜合治理配套技術(shù)研究”獲得河北省科技進(jìn)步一等獎(jiǎng)(1990年度), 作為重要成果內(nèi)容獲得國(guó)家科技進(jìn)步特等獎(jiǎng)(1993年度)和二等獎(jiǎng)(2003年度)?！笆濉逼陂g, 在河北省科技攻關(guān)計(jì)劃支持下開辟海興縣濱海鹽堿地改良利用試點(diǎn), 承擔(dān)了國(guó)家高技術(shù)研究發(fā)展計(jì)劃(863計(jì)劃)任務(wù)“海冰水資源化利用技術(shù)研究”、“十一五”公益性行業(yè)(農(nóng)業(yè))研究課題“黃淮海平原鹽堿障礙耕地農(nóng)業(yè)高效利用技術(shù)研究與模式”、“十一五”國(guó)家科技支撐計(jì)劃課題“耐鹽植物咸水安全直灌技術(shù)集成研究與示范”、國(guó)家自然科學(xué)基金課題“咸水結(jié)冰融水入滲條件下濱海鹽土的水鹽運(yùn)移規(guī)律”等一批國(guó)家、中國(guó)科學(xué)院和河北省的研究任務(wù), 形成了以鹽堿土、咸水和耐鹽植物高效利用為核心的“以鹽治鹽、適鹽用鹽”濱海鹽堿地水土資源高效利用新模式, 相關(guān)成果“河北省濱海鹽堿地適生種植技術(shù)集成研究與示范”獲得河北省科技進(jìn)步一等獎(jiǎng)(2015年度)。以此為基礎(chǔ), 承擔(dān)了“十二五”國(guó)家科技支撐計(jì)劃項(xiàng)目“渤海糧倉科技示范工程”、“十三五”國(guó)家重點(diǎn)研發(fā)計(jì)劃課題“內(nèi)蒙河套鹽堿地抗鹽生態(tài)治理和優(yōu)質(zhì)草飼生態(tài)產(chǎn)業(yè)技術(shù)研究與集成示范”等科研任務(wù)。

在國(guó)家、中國(guó)科學(xué)院和河北省以及地方政府長(zhǎng)期支持下, 歷經(jīng)3代人30余年不懈努力, 農(nóng)業(yè)資源研究中心在缺水區(qū)鹽堿地改良利用方面取得一系列的研究成果, 為保障國(guó)家糧食安全、水安全和生態(tài)安全, 促進(jìn)農(nóng)業(yè)可持續(xù)發(fā)展發(fā)揮了重要作用。

1 研究區(qū)概況

環(huán)渤海缺水鹽漬區(qū)鹽堿地主要分布于河北省的低平原和濱海平原。該區(qū)處于暖溫帶半濕潤(rùn)大陸季風(fēng)氣候區(qū), 冬季寒冷少雪, 春季干燥多風(fēng), 夏季炎熱多雨, 秋季晴朗干燥。該區(qū)光照充足, 年日照時(shí)數(shù)2 400~3 000 h, 比山麓平原區(qū)多200 h左右; 年平均氣溫10.8~13.3 ℃, 無霜期180~200 d; 低平原區(qū)年降水量450~550 mm, 濱海平原區(qū)年降水量600~700 mm, 80%的降水主要集中在7—9月。低平原區(qū)為古黃河、海河水系沖積而成, 濱海平原區(qū)為海積地貌, 地勢(shì)低平而坡降小, 地下水徑流滯緩。該區(qū)淡水資源短缺, 20世紀(jì)60年代的山區(qū)水庫修建和海河流域的排澇工程, 解決了區(qū)域的洪澇災(zāi)害問題, 也使區(qū)域的水循環(huán)發(fā)生根本變化, 區(qū)域內(nèi)河流常年斷流, 基本沒有出境徑流。本區(qū)淺層地下水埋深較淺, 由低平原區(qū)的3~5 m, 過渡到濱海平原區(qū)的1~2 m。地下水的垂直分布大部分地區(qū)為淺層淡水—咸水—深層淡水, 在大約90%以上的面積范圍內(nèi)分布巨大的咸水體, 自西向東由低平原向?yàn)I海平原, 咸水體逐漸加厚, 厚度10~200 m, 礦化度逐漸增加。低平原區(qū)在咸水體之上, 分布著少量的條帶狀與古河流有密切關(guān)系的淺層淡水, 濱海平原淺層地下水為全咸水, 含鹽量一般達(dá)10~30 g?L-1, 近海灘可達(dá)30~50 g?L-1。深層淡水的開采深度在250~800 m, 隨著工農(nóng)業(yè)用水增加, 水位不斷下降, 超采形成大面積漏斗。受土壤質(zhì)地、地下水、海水浸漬和氣候條件等的影響, 區(qū)域土壤鹽漬化嚴(yán)重[2]。按照中國(guó)土壤鹽漬區(qū)分區(qū)劃分[1], 環(huán)渤海缺水區(qū)鹽堿地分屬于黃淮海半濕潤(rùn)-半干旱耕作草甸鹽漬區(qū)(低平原區(qū))和濱海濕潤(rùn)-半濕潤(rùn)海水浸漬鹽漬區(qū)(濱海平原區(qū))。低平原區(qū)鹽漬土類型主要為鹽化潮土, 局部地方有鹽土, 以SO4-Cl或Cl-SO4鹽為主, 土壤含鹽量一般在3~5 g?kg-1, 局部高達(dá)8 g?kg-1以上; 濱海平原區(qū)鹽漬土類型主要為鹽化潮土、鹽化草甸土和濱海鹽土, 鹽漬過程先于成土過程, 鹽分以NaCl為主, 土壤含鹽量在6~23 g?kg-1之間, 沿海高達(dá)35 g?kg-1以上。在地下水和氣候條件的雙重作用下, 區(qū)域土壤鹽分存在著明顯的季節(jié)性積鹽和脫鹽, 一般為春季干旱少雨, 蒸發(fā)量大, 土壤鹽分表聚嚴(yán)重; 夏季降雨量大, 土壤表現(xiàn)為脫鹽; 秋季降雨減少, 蒸發(fā)增加, 表現(xiàn)為緩慢積鹽; 冬季氣溫降低, 土壤鹽分處于相對(duì)穩(wěn)定期, 在地下水埋深淺的地區(qū)存在凍融積鹽。

2 研究方法

針對(duì)淡水資源匱乏制約鹽堿地改良問題, 依據(jù)區(qū)域土壤水鹽運(yùn)移規(guī)律, 結(jié)合氣候條件和作物生長(zhǎng)發(fā)育規(guī)律, 以淺層地下水調(diào)控和利用為中心, 結(jié)合雨水利用, 按照“用中求治、適鹽用鹽、以鹽治鹽”的總體思路, 采用田間試驗(yàn)與室內(nèi)試驗(yàn)相結(jié)合的方法, 在低平原缺水鹽漬區(qū)的南皮縣和濱海平原鹽漬區(qū)的海興縣建立了鹽堿地改良利用試驗(yàn)區(qū), 開展了井灌條件下淺層地下水調(diào)控改良鹽堿地、咸水灌溉耕層水鹽調(diào)控、覆蓋抑鹽隔鹽、生物改土與適應(yīng)性種植等水利工程措施、農(nóng)藝與生物措施相結(jié)合的鹽堿地改良利用技術(shù)研究, 與地方政府緊密結(jié)合, 規(guī)?；茝V應(yīng)用鹽堿地改良利用成果。

3 主要成果

3.1 明確了低平原缺水鹽漬區(qū)鹽堿地改良的淺層地下水埋深調(diào)控深度, 建立了井灌代排、蓄雨淋鹽的鹽堿地改良技術(shù)模式

低平原區(qū)春旱、夏澇, 地下水位淺且水質(zhì)咸, 當(dāng)?shù)叵滤宦裆钤谕寥婪蝶}臨界水位附近變化時(shí), 土壤鹽分呈春季蒸發(fā)積鹽-雨季淋溶脫鹽的周期性變化。根據(jù)多年試驗(yàn)研究和調(diào)查結(jié)果, 制定了不同季節(jié)防治旱澇堿咸的地下水臨界埋深動(dòng)態(tài)指標(biāo)[3]: 旱季控制在防治鹽堿化的地下水臨界深度(2~3 m)以下, 雨季前控制在防澇蓄雨深度(4~6 m), 雨季控制水位不小于作物的抗?jié)裆疃?0.5~1.0 m), 以此達(dá)到旱季減蒸控鹽、雨季淋鹽改咸目的。根據(jù)地下水臨界埋深動(dòng)態(tài)調(diào)控指標(biāo), 采用井灌方式, 以井抗旱、以灌代排, 夏蓄春用周年調(diào)節(jié)方式, 達(dá)到抗旱除澇治堿改咸一體化的目的。研究結(jié)果表明[3], 春季大量提取淺層地下水抗旱灌溉, 增加重力水下滲, 可改變土壤自然蒸發(fā)積鹽趨勢(shì), 加速土壤淋鹽。在根層土壤含鹽量2 g?kg-1的輕度鹽堿地上, 一次灌水750~825 m3?hm-2, 0~30 cm土層脫鹽達(dá)33%~56%, 30~100 cm土層脫鹽達(dá)23%~32%。井灌降低地下水位以后, 降雨可使大面積鹽堿地脫鹽。據(jù)實(shí)際觀測(cè)結(jié)果[3], 汛前(地下水埋深4~5 m)一次降雨量為25 mm、76 mm和159 mm時(shí), 0~40 cm土層脫鹽率分別為30%、35%和45%。由于春季井灌降低了地下水位, 可增大降雨入滲, 減少地表徑流, 除補(bǔ)給土壤水以外, 大部分轉(zhuǎn)化為地下水, 且促使淺層地下水的淡化。據(jù)研究[4], 在平水年雨季降水434 mm情況下, 降雨入滲補(bǔ)給地下水量最大值相應(yīng)的雨季前埋深在4.5 m左右;在雨季前地下水埋深2.5~4.5 m范圍內(nèi), 地下水每降深1 m, 降雨入滲補(bǔ)給地下水的數(shù)量增加6~22 mm。雨季前地下水埋深大于4.5 m時(shí), 降雨入滲將隨埋深增大而減少。

采用上述技術(shù), 在南皮縣建立的常莊試區(qū), 1983—1988年5年間, 土壤耕層的含鹽量由3.86 g?kg-1降低到1.36 g?kg-1, 鹽化潮土的面積由占耕地的21%減少到5%, 淺層淡水面積擴(kuò)大了43.5%, 微咸水面積縮小了42.8%[5]。

3.2 揭示了咸水結(jié)冰融水咸淡水分離與在濱海鹽土的入滲規(guī)律, 發(fā)明了冬季咸水結(jié)冰灌溉改良濱海重鹽堿地技術(shù)

環(huán)渤海濱海鹽堿地受海積地貌影響, 海拔低, 地下水埋深淺, 礦化度高, 土壤鹽漬化嚴(yán)重, 淡水資源匱乏, 難于采用地下水臨界水位調(diào)控的水利工程措施進(jìn)行改造。“鹽隨水來, 鹽隨水去”, 國(guó)內(nèi)外的研究已經(jīng)表明, 鹽堿地改良利用的核心是“水”。對(duì)于淡水資源匱乏的濱海鹽堿區(qū), 其豐富的咸水資源和降雨資源的利用是區(qū)域鹽堿地改良利用的核心。針對(duì)濱海鹽堿區(qū)春季蒸發(fā)量大、降水少, 土壤返鹽嚴(yán)重, 影響作物播種出苗和生長(zhǎng)問題, 依據(jù)咸水結(jié)冰凍融咸淡水分離原理, 我們發(fā)明了冬季咸水結(jié)冰灌溉改良濱海重鹽堿地技術(shù)。

咸水結(jié)冰融水試驗(yàn)結(jié)果表明[6-7], 由于不同礦化度咸水的冰點(diǎn)不同, 咸水冰融化時(shí), 融水礦化度逐漸下降, 脫鹽效果顯著, 且與融冰溫度有關(guān)。在-3 ℃時(shí), 10 g?L-1的咸水冰最初融化的水礦化度高達(dá)130 g?L-1, 而融水體積僅占總體積的0.75%, 到融水占總?cè)谒康?9%時(shí), 脫鹽率已達(dá)99.6%, 剩余冰含鹽量已降至0.063 g?L-1。其他溫度條件, 當(dāng)50%的冰融化時(shí), 脫鹽率均達(dá)95%以上。咸水冰融化過程中, 融水的鈉吸附比也逐漸下降。由于咸水結(jié)冰融水礦化度的變化, 影響融水在鹽漬土的入滲。土柱試驗(yàn)表明[7-8], 相對(duì)于淡水冰融水入滲, 咸水冰融水入滲速度快、深度深, 且隨咸水冰礦化度和水量升高, 以180 mm灌水量最好。在土壤含鹽量達(dá)10~20 g?kg-1, 180 mm的5~15 g?L-1的咸水冰融水入滲完成后0~20 cm土壤脫鹽率達(dá)95%以上, 高于淡水冰的84%。咸水冰的鈉吸附比影響融水入滲但對(duì)脫鹽效果沒有顯著影響。田間試驗(yàn)結(jié)果表明[9], 冬季當(dāng)氣溫小于-5 ℃, 對(duì)濱海鹽土灌溉180 mm小于15 g?L-1的咸水, 地表能形成穩(wěn)定冰層, 春季咸水冰融化后, 土壤含鹽量降至4 g?kg-1以下, 而沒灌溉的土壤含鹽量高達(dá)27 g?kg-1。由于春季蒸發(fā)量大, 咸水冰融水入滲完成需結(jié)合抑鹽措施防止土壤返鹽。春季結(jié)合地膜覆蓋可顯著降低土壤鹽分含量和提高土壤含水量[10-14]。2009—2011年咸水結(jié)冰灌溉覆膜處理棉花(spp.)播種期0~20 cm土壤鹽分含量分別為3.2 g?kg-1、2.9 g?kg-1和1.7 g?kg-1, 土壤含水量分別為26.2%、25.0%和24.2%, 棉花出苗率均達(dá)到85%。之后結(jié)合雨季淋鹽, 整個(gè)生育期土壤含鹽量維持3 g?kg-1以下, 保證了棉花等作物的正常生長(zhǎng), 使不能生長(zhǎng)農(nóng)作物的濱海重鹽堿地當(dāng)年棉花產(chǎn)量達(dá)3 000 kg?hm-2以上。咸水結(jié)冰灌溉同時(shí)促進(jìn)了大顆粒土壤團(tuán)聚體的形成[15], 增加土壤微生物的數(shù)量[16], 有利于土壤鹽分的淋洗和土壤肥力的提高。

依據(jù)上述研究結(jié)果, 形成了以冬季咸水結(jié)冰灌溉為主體, 結(jié)合覆蓋抑鹽、雨水淋鹽的濱海重鹽堿地改良利用技術(shù)體系, 為淡水資源匱乏的濱海重鹽堿地的開發(fā)利用提供了支撐。

3.3 提出了耦合鹽堿區(qū)土壤水鹽運(yùn)移-氣候條件-植物生長(zhǎng)發(fā)育規(guī)律的鹽堿地改良思路, 建立了微域降鹽、秸稈隔鹽的鹽堿地農(nóng)藝改良技術(shù)模式

在季風(fēng)氣候區(qū), 作物生長(zhǎng)、氣候條件和土壤的水鹽運(yùn)移, 既有矛盾, 又有統(tǒng)一[17]。植物的生長(zhǎng)發(fā)育具有階段性耐鹽特征[18], 種子發(fā)芽和苗期生長(zhǎng)階段是鹽敏感時(shí)期, 之后耐鹽能力逐步提高。在季風(fēng)氣候區(qū), 春季蒸發(fā)量大、降水少, 為強(qiáng)烈的蒸發(fā)積鹽階段, 這一時(shí)期又是一般植物的發(fā)芽和苗期生長(zhǎng)階段, 如果土壤含鹽量高則影響植物的正常生長(zhǎng); 夏季降雨量大, 是土壤脫鹽期, 且雨熱同季, 能夠保證作物快速生長(zhǎng)發(fā)育; 秋季雖然處于土壤緩慢積鹽時(shí)期, 但植物處于生長(zhǎng)后期, 耐鹽能力較強(qiáng)。因此, 春季創(chuàng)造適宜的植物出苗生長(zhǎng)的微域低鹽環(huán)境, 是實(shí)現(xiàn)季風(fēng)氣候區(qū)植物生長(zhǎng)的關(guān)鍵。

研發(fā)的開溝起壟、微域降鹽“三微兩覆”重鹽堿地快速改良技術(shù)[3], 采用開溝起壟(溝寬0.5~1.0 m, 溝深0.2 m, 壟背寬0.5~1.5 m)的微工程, 微量深井水(225 m3?hm-2)進(jìn)行溝灌洗鹽保苗, 壟背覆地膜集雨防鹽, 溝內(nèi)覆秸稈保墑, 改善了水鹽微循環(huán)過程, 在溝底及其兩側(cè)形成了一個(gè)土壤脫鹽淡化區(qū), 土壤含鹽量全年穩(wěn)定在2.0 g?kg-1以下, 通過種植高經(jīng)濟(jì)價(jià)值的瓜菜, 實(shí)現(xiàn)鹽堿地的快速治理和高效生產(chǎn)。研發(fā)的基于秸稈深埋隔鹽的“濱海鹽堿地兩相耕作法小麥()快速增產(chǎn)技術(shù)”[19-20], 采用雨季淋鹽期種植高稈作物, 如玉米(), 收獲時(shí)采用深耕犁整株翻埋于耕層以下20 cm, 形成秸稈隔鹽層, 然后播種冬小麥。由于秸稈層阻止了春季返鹽期土壤鹽分隨水分上移, 維持了耕層低鹽環(huán)境, 保證了冬小麥正常生長(zhǎng)。采用該項(xiàng)技術(shù), 在春季返鹽期, 土壤耕層鹽分保持在3 g?kg-1以下, 而無秸稈隔層的達(dá)6 g?kg-1以上, 冬小麥產(chǎn)量可提高15%~100%以上。

據(jù)此, 提出了耦合鹽堿區(qū)土壤水鹽運(yùn)移-氣候條件-植物生長(zhǎng)發(fā)育規(guī)律的鹽堿地改良思路[17], 并形成了以微域降鹽和秸稈隔鹽為主的鹽堿地農(nóng)藝改良技術(shù)模式。上述技術(shù)模式也應(yīng)用到了寧夏[21-22]、江蘇[23]等地的鹽堿地治理當(dāng)中。

3.4 探討了鹽生植物適應(yīng)鹽漬環(huán)境的機(jī)理, 建立了濱海鹽堿地鹽漬資源高效利用技術(shù)體系

耐鹽植物種植是鹽堿地改良利用的主要生物措施。農(nóng)業(yè)資源中心“七五”期間在低平原中輕度鹽漬區(qū)通過種植苜蓿(), 取得了較好的效果。研究結(jié)果表明[3], 通過種植苜蓿增加了植被覆蓋, 改善了土壤結(jié)構(gòu), 土壤鹽分有下降的趨勢(shì)。但由于苜蓿收獲帶走的鹽分有限, 僅靠生物排鹽不足以消除鹽漬化的威脅。這就為我們提出了個(gè)問題, 就是直接種植耐鹽植物把鹽堿地高效利用起來。1991年在中日合作“提高黃淮海平原鹽堿地生物生產(chǎn)力”項(xiàng)目的支持下, 開始規(guī)模化引進(jìn)篩選耐鹽植物品種。2001年組織召開了首屆“國(guó)際鹽生植物利用與區(qū)域農(nóng)業(yè)可持續(xù)發(fā)展學(xué)術(shù)研討會(huì)”, 推動(dòng)了我國(guó)鹽生植物的研究利用。

在鹽生植物適應(yīng)鹽漬環(huán)境機(jī)理方面, 我們研究明確了鹽生植物的發(fā)芽需要一定的低鹽環(huán)境[24-27]、鹽生植物種子二型性的耐鹽差異及調(diào)控機(jī)制[28-31]、干旱條件下適當(dāng)?shù)柠}分脅迫促進(jìn)鹽生植物的生長(zhǎng)[32]、鹽脅迫下增加氮可提高鹽生植物的耐鹽能力[33]、不同鹽生植被類型土壤鹽分和養(yǎng)分存在著差異[34]、土壤水鹽差異影響不同類型鹽生植物的分布[35]、鹽生植物根系在差異化土壤鹽分下具有補(bǔ)償效應(yīng)[36]等, 同時(shí)研究了鹽生植物的開發(fā)利用價(jià)值[37]以及鹽生植物種植的改土[38]與碳匯效應(yīng)[39-40]。在開展機(jī)理研究的同時(shí), 開展了鄉(xiāng)土鹽生植物品種的篩選與馴化工作, 審定了具有耐鹽、優(yōu)質(zhì)、高產(chǎn)的枸杞()品種‘鹽杞’和‘海杞’, 具有耐鹽、生長(zhǎng)迅速、樹形美觀的檉柳()品種‘海檉1號(hào)’, 同時(shí)收集保存了一批耐鹽的種質(zhì)資源。

根據(jù)鹽生植物的耐鹽特征, 結(jié)合咸水利用和微域降鹽措施, 采用覆蓋、咸水灌溉、耕翻、耬劃、補(bǔ)施氮磷、育苗穴植等措施, 在濱海重鹽堿地建立起了以耐鹽(鹽生)植物、鹽堿地和咸水利用相結(jié)合的鹽漬資源高效利用技術(shù)體系, 形成了鹽堿地耐鹽作物種植、經(jīng)濟(jì)鹽生植物種植、鹽堿地原土綠化模式, 在河北省海興、黃驊、曹妃甸以及天津?yàn)I海地區(qū)進(jìn)行了示范應(yīng)用, 為濱海鹽堿地適應(yīng)性開發(fā)利用和生態(tài)環(huán)境改善提供了科技支撐。

4 展望

我們的實(shí)踐表明, 鹽堿地的改良利用“水”是核心, 通過合理利用水資源, 特別是在環(huán)渤海缺水鹽漬區(qū)科學(xué)利用降雨和淺層地下咸水資源, 創(chuàng)造適宜植物生長(zhǎng)的低鹽根層環(huán)境, 結(jié)合農(nóng)藝和生物措施, 走與自然和諧共生的鹽堿地改良利用之路, 可實(shí)現(xiàn)鹽堿地的高效開發(fā)。隨著社會(huì)經(jīng)濟(jì)發(fā)展, 人們對(duì)鹽堿地的開發(fā)利用提出了多樣化需求。下一步, 在保障糧食安全基礎(chǔ)上, 牢記綠水青山就是金山銀山, 堅(jiān)持人與自然和諧共生方略, 在鹽堿地改良利用理論與技術(shù)方面重點(diǎn)需要從以下幾個(gè)方面突破:

一是鹽堿地植物根土界面水鹽調(diào)控理論與技術(shù)。鹽堿地改良的目的是創(chuàng)造適宜植物生長(zhǎng)的根層環(huán)境, 植物的生長(zhǎng)離不開水和養(yǎng)分。低鹽植物根層環(huán)境的創(chuàng)建, 需要揭示植物根土界面的水分、鹽分、養(yǎng)分的互作關(guān)系以及形成根土界面適宜的水分、養(yǎng)分和鹽分的技術(shù), 如大顆粒土壤團(tuán)聚體的構(gòu)建技術(shù)等。二是加強(qiáng)鹽堿地節(jié)水改良技術(shù)的研發(fā)。研究鹽堿地改良利用的咸水灌溉、雨水集蓄、節(jié)水改土等技術(shù), 建立多水源利用改土的技術(shù)體系。三是加強(qiáng)耐鹽作物和經(jīng)濟(jì)鹽生植物的篩選培育。利用傳統(tǒng)和現(xiàn)代生物學(xué)技術(shù), 篩選培育耐鹽作物, 特別是加強(qiáng)經(jīng)濟(jì)鹽生植物的篩選、評(píng)價(jià)以及適宜的栽培技術(shù)研究。四是加強(qiáng)鹽堿地植被建設(shè)技術(shù)的研究。變傳統(tǒng)的改造為適應(yīng)性種植, 特別要注重鹽堿地原土草場(chǎng)建植及綠化技術(shù)的研發(fā)。五是加強(qiáng)鹽堿地開發(fā)利用的生態(tài)效應(yīng)評(píng)價(jià)。特別是鹽堿地改良利用的水土資源效應(yīng)、固碳增匯效應(yīng)等, 為鹽堿地的可持續(xù)開發(fā)提供支撐。

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Reclamation and utilization of saline soils in water-scarce regions of Bohai Sea*

LIU Xiaojing

(Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences / Key Laboratory of Agricultural Water Resources, Chinese Academy of Sciences / Hebei Key Laboratory of Water-Saving Agriculture, Shijiazhuang 050022, China)

Freshwater scarcity is one of the main constraints to the reclamation of saline soils. Research and demonstration studies on the reclamation and utilization of saline soils in water-scarce regions of Bohai Sea started since 1982 in Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences. The experiments had included regulation of shallow groundwater table via well-water irrigation and rainwater recharge, soil salt leaching via saline water irrigation, root-zone soil desalination via agronomic methods and utilization of halophytes. The major achievements were as follows: 1) the regulating levels of shallow groundwater table were determined and the patterns of management by well-water irrigation and rainwater leaching to control soil salinization in lowland plains established. Through well-water irrigation, the critical level of shallow groundwater table was kept at >2-3 m during the dry season to reduce soil evaporation and control soil salinization. This was further reduced to 4-6 m before the rains to enhance rainwater recharge and in turn leaching of soil salts and dilution of saline groundwater. Next the groundwater table was kept at >0.5-1.0 m during the rains again to assure healthy crop growth. After the implementation of this method in Changzhuang Town (Nanpi County in Hebei Province) for the period 1983–1988, soil salt content decreased from 3.86 g?kg-1to 1.36 g?kg-1, and the area of saline Chao soil and saline groundwater dropped by 76.2% and 42.8%, respectively. 2) The separation process of saline water and freshwater by melting saline ice and its infiltration into saline soil were revealed and the method of reclamation of coastal saline soils by freezing saline water in winter invented. Lab experiments showed that saline ice was desalinized efficiently by melting, which produced about 60% low salinity (< 4 g?L-1) water from melting saline ice (< 15 g?L-1). Also the infiltration of saline ice melt-water reduced surface soil salt content. Field experiments indicated that by freezing saline water (< 15 g?L-1) irrigation in winter (<-5 ℃) combined with plastic film or straw mulching and rainwater leaching improved coastal saline soil. The soil salt content in 0-20 cm was less than 3.0 g?kg-1during the growing season under freezing saline water irrigation, while it exceeded 10 g?kg-1under control (no irrigation) treatment. 3) Trough coupling of the dynamics of soil salt and water, climate and plant growth, the agronomic patterns of soil salinization control in the root zone was established via ridging, mulching and straw incorporation into the deep soil layer. In monsoon climate regions, there was soil salinization in spring due to low rainfall and high evaporation, and then soil desalinized in summer due to high rainfall. Seed germination and seedling growth were the salt-sensitive stages, which usually occurred in spring. Therefore, it was important to create low salinity in the root zone for health growth of plant in spring. In order to desalinize the root zone soil, field ridging in spring and straw incorporation in autumn were studied. The results showed that field ridging, combined with plastic film and straw mulching, reduced soil salinity to 2.0 g?kg-1and straw incorporation into deep soil layer controlled the soil salinity in spring at < 3 g?kg-1. 4) The adaptive mechanisms of halophytes to saline soils were explored and the pattern of efficient utilization of saline resources established. For the utilization of saline soils and saline water, salt tolerant plants and halophytes were collected and screened. The effects of salt stress, combined with those of water and nutrient application, on seed germination and plant growth were studied. The results showed that seed germination required low salinity, moderate salinity alleviated drought stress on seed germination and seedling growth, NO played a very important role in the regulation of salt tolerance of seedlings derived from dimorphic seeds of, and N application increased the growth of halophytes under salt stress, etc. Based on the characteristics of salt tolerance of different plants, the method of growing plants in saline soils was established. This included land plowing, holing cultivation, fertilizer application, frozen saline water irrigation, mulching, etc. The application of the above results has supported crop production and ecological rehabilitation of saline soils in water-scarce regions of Bohai Sea.

Bohai Sea; Water scarcity; Saline soil; Well-water irrigation; Root-zone soil desalinization; Saline water irrigation; Halophyte

, LIU Xiaojing, E-mail: xjliu@sjziam.ac.cn

Jul. 25, 2018;

Aug. 5, 2018

10.13930/j.cnki.cjea.180725

S287; S343.4

A

1671-3990(2018)10-1521-07

2018-07-25

2018-08-05

*The study was supported by the Science and Technology Service Network Initiative of Chinese Academy of Sciences (KFZD-SW-112-4).

*中國(guó)科學(xué)院科技服務(wù)網(wǎng)絡(luò)(STS)計(jì)劃項(xiàng)目(KFZD-SW-112-4)資助

劉小京, 主要從事鹽堿地水土資源高效利用研究。E-mail: xjliu@sjziam.ac.cn

劉小京. 環(huán)渤海缺水區(qū)鹽堿地改良利用技術(shù)研究[J]. 中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào), 2018, 26(10): 1521-1527

LIU X J. Reclamation and utilization of saline soils in water-scarce regions of Bohai Sea[J]. Chinese Journal of Eco-Agriculture, 2018, 26(10): 1521-1527