基于變量選擇的堆肥胡敏酸含量近紅外光譜分析

李自剛 岳曉禹 李長濱 張春輝 魏慶葆 劉世亮

(1.河南牧業(yè)經(jīng)濟學院包裝與印刷工程學院， 鄭州 450011；2.河南牧業(yè)經(jīng)濟學院河南省生豬疾病防控工程技術(shù)研究中心， 鄭州 450011；3.澳大利亞動物衛(wèi)生實驗室， 吉朗 3220； 4.河南農(nóng)業(yè)大學資源環(huán)境學院， 鄭州 450002)

基于變量選擇的堆肥胡敏酸含量近紅外光譜分析

李自剛1,2岳曉禹1李長濱1張春輝2,3魏慶葆1劉世亮4

(1.河南牧業(yè)經(jīng)濟學院包裝與印刷工程學院， 鄭州 450011；2.河南牧業(yè)經(jīng)濟學院河南省生豬疾病防控工程技術(shù)研究中心， 鄭州 450011；3.澳大利亞動物衛(wèi)生實驗室， 吉朗 3220； 4.河南農(nóng)業(yè)大學資源環(huán)境學院， 鄭州 450002)

為探討基于選擇的近紅外光譜變量定量判別堆肥腐熟度的可能性，為堆肥發(fā)酵終點判定及開發(fā)相應(yīng)的近紅外漫反射光譜控制設(shè)備提供理論基礎(chǔ)，采集了100份堆肥樣本，用濕化學方法分析了堆肥樣本中的胡敏酸含量，采集范圍為4 000～9 000 cm-1波段的光譜，進而利用該近紅外光譜進行預(yù)處理方法的優(yōu)化研究及堆肥胡敏酸感變量的優(yōu)選研究，以偏最小二乘的方法建立了基于近紅外光譜分析的堆肥胡敏酸定量模型。結(jié)果表明：小波變換充分提取了近紅外光譜的信息；利用C4小波系數(shù)對58個堆肥樣本進行建模，對42個預(yù)測集樣本進行預(yù)測，預(yù)測集均方根誤差和R2分別為0.113 8%和0.926 6，優(yōu)于原始光譜直接建模的0.167 2%和0.834 8。對近紅外光譜數(shù)據(jù)進行小波變換，利用處理后的小波系數(shù)，采用偏最小二乘法預(yù)測了堆肥中胡敏酸的含量，建立了小波變換與近紅外光譜技術(shù)結(jié)合用于測定堆肥樣品中胡敏酸測定的模型?；谛〔ㄏ禂?shù)的模型優(yōu)于傳統(tǒng)的近紅外光譜全譜模型，對于堆肥胡敏酸的測定取得了較為準確的預(yù)測結(jié)果。

堆肥; 品質(zhì)控制; 腐熟度評價; 胡敏酸； 近紅外光譜； 小波變換

引言

堆肥是在多種微生物的作用下，將有機固體廢棄物進行礦質(zhì)化、腐殖化、穩(wěn)定化以及無害化的發(fā)酵過程，腐熟的堆肥不僅可以提高作物的產(chǎn)量，改善農(nóng)產(chǎn)品的品質(zhì)，還能改善土壤的物理化學性質(zhì)，是一種優(yōu)質(zhì)的有機肥[1-4]。堆肥發(fā)酵生產(chǎn)有機肥時，發(fā)酵終點判定或堆肥腐熟度評價是該領(lǐng)域的研究熱點[4-10]。

養(yǎng)分含量、含水率、pH值、電導(dǎo)率等理化指標常用于堆肥發(fā)酵終點的判定或腐熟度評價[8-14]，在堆肥發(fā)酵過程中，腐殖質(zhì)類物質(zhì)是堆肥腐熟度評價的重要指標，胡敏酸(Humic acid, HA)是腐殖質(zhì)類物質(zhì)的主要組成物質(zhì)，其通常是判定有機肥品質(zhì)及農(nóng)田施用效果的主要指標[1,14-15]。胡敏酸結(jié)構(gòu)組成及性質(zhì)與土壤的保肥和供肥性能相關(guān)[16-17]，近年來，胡敏酸的光譜學分析大都集中在紅外光譜或紅外光譜與熱重分析聯(lián)用領(lǐng)域[18-20]，有關(guān)近紅外光譜(Near infrared reflectance spectroscopy,NIRS)分析技術(shù)在該領(lǐng)域的研究報道并不多見。

在建?？焖俜治鲱I(lǐng)域，NIRS分析技術(shù)已被應(yīng)用于工業(yè)、農(nóng)業(yè)、環(huán)境等領(lǐng)域[21-26]。進入21世紀以來，隨著計算機技術(shù)軟硬件的發(fā)展，NIRS分析技術(shù)在堆肥發(fā)酵控制領(lǐng)域顯示出廣闊的應(yīng)用前景[27-28]。

本文以胡敏酸為目標物，利用NIRS和偏最小二乘法建立堆肥發(fā)酵腐熟度評價方法，以期為利用NIRS技術(shù)控制堆肥發(fā)酵過程設(shè)備研發(fā)提供理論基礎(chǔ)。

1 材料與方法

1.1 儀器與試劑

Bruker MPA FT-NIR型光譜儀(Bruker Optics Inc.)，石英分束器，積分球檢測附件(漫反射)，PbS檢測器；AA3型連續(xù)流動分析儀(德國Bran+Lubbe公司)；胡敏酸(色譜純，美國Sigma-Aldrich公司)；NaOH、Na4P2O4、HCl(均為分析純，中國醫(yī)藥集團上?；瘜W試劑公司)。

1.2 堆肥方法及取樣

堆肥試驗于2013年5月1日—2014年5月1日在中荷河南奶業(yè)培訓示范中心基地(河南省鄭州市花園口鎮(zhèn)六堡村)生態(tài)堆肥廠進行，堆肥原材料主要有鋸木屑(A)、稻糠(B)，購自于六堡村家具加工廠和碾米廠；新鮮奶牛糞便(C)收集自中荷河南奶業(yè)培訓示范中心基地奶牛養(yǎng)殖棚；成品有機肥(D)由中荷河南奶業(yè)培訓示范中心基地生態(tài)堆肥廠生產(chǎn)。其中A、B、D用于調(diào)整C起始時的水分，堆肥發(fā)酵時堆肥原料的起始濕度為(65±0.5)%。堆肥發(fā)酵終點(堆肥腐熟穩(wěn)定判定)采用DOU等[29]所推薦的方法判定，堆肥結(jié)束后，從堆肥堆體的不同位置點(位置點個數(shù)大于10)各平行取樣3次，每次250 g，并將分批次取得的樣品充分混勻，之后再從中平行取樣3次，每次250 g，取樣后將樣品于0～5℃冰箱冷藏貯存以供分析。取回后的樣品放入真空冷凍干燥器于-59℃條件下真空冷凍干燥24 h后，碾磨成粉狀，過40目篩后封裝在牛皮紙袋中，保存于干燥器內(nèi)以避免吸收空氣中水分而受潮，保存樣品以備后續(xù)試驗。

1.3 堆肥樣品中胡敏酸的提取

根據(jù)國際腐殖質(zhì)協(xié)會的標準方法對堆肥樣品中的胡敏酸樣品進行提取與純化[30]。具體操作如下：稱取1.2節(jié)中的堆肥樣品20 g(干基)，將其溶于150 mL胡敏酸提取液(胡敏酸提取液由0.1 mol/L NaOH和0.1 mol/L Na4P2O4溶液按1∶1的體積比配制而成)中，室溫((25±1)℃)下振蕩24 h，然后于8 000 r/min離心條件下離心10 min后取上清液進行酸化并靜置12 h，酸化環(huán)境為6 mol/L HCl，pH值為2.0；然后離心取絮狀褐色沉淀，用超純水沖洗沉淀直至沖洗液無Cl-檢出，將其沉淀凍干保存，用于近紅外光譜測定與分析。

1.4 近紅外光譜測定方法

用AA3型連續(xù)流動分析儀測試堆肥樣品中胡敏酸含量，作為標準值。

用Bruker MPA FT-NIR型光譜儀測試粉狀堆肥樣品的NIR光譜，近紅外光譜的測定條件為：光譜采集范圍為4 000～9 000 cm-1；分辨率為4 cm-1；掃描次數(shù)為64次；溫度為室溫；實驗室經(jīng)除濕處理100個堆肥樣品的NIR光譜如圖1所示，100個堆肥樣品NIR光譜的每條譜線由1 298個數(shù)據(jù)點構(gòu)成。

圖1 堆肥樣品的近紅外光譜圖譜Fig.1 NIR spectra of 100 compost samples

1.5 數(shù)據(jù)處理

利用小波變換對獲得的NIR光譜數(shù)據(jù)進行處理，小波變換是在傅里葉變換基礎(chǔ)上發(fā)展起來的，可用于數(shù)據(jù)壓縮、多組分信號重疊解析、基線校正。小波分析是基于離散小波變換(Discrete wavelet transform,DWT)的多尺度信號分解(Multiresolution signal decomposition, MRSD)算法，核心算法為

(1)

(2)

由Cj和Dj可以重構(gòu)C0。

(3)

偏最小二乘法(Partial least square method,PLS)對化學量測矩陣Y和濃度矩陣X同時進行主成分分解，并以主因子進行回歸。利用壓縮后的小波系數(shù)進行PLS建模，進一步提高了方法的計算速度和可靠性。

2 結(jié)果與分析

2.1 小波分解尺度選擇與預(yù)測模型確定

以上述獲得的原始NIR數(shù)據(jù)以及1～7階離散小波變換處理后得到的小波系數(shù)(C0～C7；D1～D7)分別建模和預(yù)測堆肥樣品中的胡敏酸含量，以預(yù)測與試驗測定值之間的決定系數(shù)R2考察預(yù)測模型，結(jié)果如表1所示。本文選擇的小波函數(shù)為Daubechies。

表1 不同尺度效應(yīng)下的建模和預(yù)測結(jié)果Tab.1 Modeling and prediction in different scales

2.2 DWT對NIR光譜信息的提取

為進一步考察DWT對NIR光譜信息的提取能力，圖2給出了20號堆肥樣品NIRC4直接重構(gòu)的結(jié)果。從圖2可以看出，雖然由C4直接重構(gòu)后的圖譜與NIR光譜的形狀具有一定差別，但這些系數(shù)包含了被測成分測定的主要信息，扣除了一定的噪聲信號。此結(jié)果充分說明了DWT對NIR有用信息的提取能力。

圖2 20號堆肥樣品的近紅外光譜圖譜Fig.2 NIR spectra reconstructed from C4 coefficient for No.20 compost samples

2.3 堆肥樣品中胡敏酸含量的預(yù)測

胡敏酸是堆肥發(fā)酵腐熟度(堆肥品質(zhì))的重要指標之一[1,11,14-15,31]，在樣品預(yù)處理方法為一階導(dǎo)數(shù)結(jié)合多元散射校正處理的情況下，主成分數(shù)選擇4時，從100個堆肥樣品中均勻選取58個作為PLS建模的校正集，另外42個作為預(yù)測集，直接用全譜建模，相應(yīng)的結(jié)果如圖3所示，校正集預(yù)測均方根誤差為0.465 3%，預(yù)測集均方根誤差為0.167 2%，R2為0.834 8，預(yù)測結(jié)果的相對誤差在-3.77%～3.56%之間。以C4建模預(yù)測，胡敏酸含量質(zhì)量分數(shù)的預(yù)測值與試驗測定值如圖4所示，校正集均方根誤差為0.352 5%，預(yù)測集均方根誤差為0.113 8%，R2為0.926 6，預(yù)測結(jié)果的相對誤差在-2.87%～2.57%之間，可以滿足堆肥胡敏酸化學分析中對胡敏酸測定的要求。

圖3 堆肥樣品中胡敏酸質(zhì)量分數(shù)實際值與預(yù)測值的DWT交叉驗證Fig.3 Cross-validation of predicted and actual humic acid (HA) contents with DWT method

3 結(jié)束語

相比于堆肥腐殖質(zhì)另一組成成分富里酸，胡敏酸在結(jié)構(gòu)方面具有持續(xù)性和穩(wěn)定性[1,10-14,31]，研究表明NIR技術(shù)可以用于堆肥樣品中胡敏酸含量的測定?；谝欢ǚ纸獬叨菵WT處理后得到小波系數(shù)的PLS預(yù)測模型優(yōu)于傳統(tǒng)的NIR全譜處理模型，可以改善堆肥發(fā)酵腐熟度評價方法的預(yù)測準確度。由于應(yīng)用NIR技術(shù)對堆肥樣品中胡敏酸含量進行預(yù)測使得對胡敏酸繁瑣的常規(guī)化學分析變得簡便易行。本文所提出的方法，為近紅外光譜分析技術(shù)在堆肥發(fā)酵終點判定及堆肥腐熟度評價、組分含量測定、品質(zhì)評價以及應(yīng)用近紅外光譜分析技術(shù)研發(fā)堆肥發(fā)酵過程控制設(shè)備提供了理論基礎(chǔ)，有望成為堆肥發(fā)酵腐熟度評價方法中的一種有效方法。

圖4 堆肥樣品中胡敏酸質(zhì)量分數(shù)實際值與預(yù)測值的近紅外分析交叉驗證Fig.4 Cross-validation of predicted and actual humic acid (HA) contents with raw spectra

1 付強,袁野,崔嵩.農(nóng)村固體廢棄物堆肥胡敏酸還原土壤Fe3+礦物研究[J/OL].農(nóng)業(yè)機械學報, 2016,47(10):202-208. http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?file_no=20161026&flag=1.DOI:10.6041/j.issn.1000-1298.2016.10.026. FU Qiang,YUAN Ye,CUI Song.Structure evolution of compost-derived HAs from rural solid waste and corresponding reduction of Fe3+mineral from soil[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2016,47(10):202-208. (in Chinese)

2 徐鵬翔,孫敏捷,李季.規(guī)?；馀黾S污收集與堆肥處理工藝設(shè)計[J].農(nóng)業(yè)工程學報,2016,32(增刊2):213-217. XU Pengxiang,SUN Minjie,LI Ji.Feces collection and composting technological design on scaled beef cattle farms[J].Transactions of the CSAE,2016,32(Supp.2):213-217. (in Chinese)

3 李丹陽,李恕艷,李國學,等.添加劑對豬糞秸稈堆肥的氮素損失控制效果[J].農(nóng)業(yè)工程學報,2016,32(增刊2):260-267. LI Danyang, LI Shuyan, LI Guoxue, et al. Effects of additive on nitrogen loss during composting of pig manure and corn straw[J].Transactions of the CSAE,2016,32(Supp.2):260-267.(in Chinese)

4 李恕艷,李吉進,張邦喜,等.菌劑對雞糞堆肥腐殖質(zhì)含量品質(zhì)的影響[J].農(nóng)業(yè)工程學報,2016,32(增刊2):268-274. LI Shuyan, LI Jijin, ZHANG Bangxi, et al. Influence of inoculants on content and quality of humus during chicken manure composting[J].Transactions of the CSAE,2016,32(Supp.2):268-274.(in Chinese)

5 曹云,常志州,黃紅英,等. 添加腐熟豬糞對豬糞好氧堆肥效果的影響[J].農(nóng)業(yè)工程學報,2015,31(21):220-226. CAO Yun, CHANG Zhizhou, HUANG Hongying, et al. Effect of compost inoculation on pig manure composting[J].Transactions of the CSAE,2015,31(21):220-226.(in Chinese)

6 李春萍,李國學,李玉春,等.北京南宮靜態(tài)堆肥隧道倉不同區(qū)間的垃圾堆肥腐熟度模糊評價[J].農(nóng)業(yè)工程學報,2007,23(2):201-206. LI Chunping, LI Guoxue, LI Yuchun, et al. Fuzzy mathematics-based evaluation of municipal solid waste compost maturities in different spaces in static tunnel from Nangong compost plant[J].Transactions of the CSAE,2007,23(2):201-206.(in Chinese)

7 王敦球,潘盛.模糊綜合評價法在評價堆肥腐熟度中的應(yīng)用[J].農(nóng)業(yè)環(huán)境科學學報,2005,24(增刊1):212-215. WANG Dunqiu,PAN Sheng.Application of fuzzy mathematics assessment in the compost maturity evaluation[J].Journal of Agro-Environment Science,2005,24(Supp.1):212-215.(in Chinese)

8 潘玲陽,李國學,李春萍,等.不同粒徑生活垃圾對腐熟度影響統(tǒng)計分析(簡報)[J].農(nóng)業(yè)工程學報,2008,24(10):209-213. PAN Lingyang,LI Guoxue,LI Chunping,et al. Statistics analysis of the effects from different sized municipal solid wastes on compost maturities[J].Transactions of the CSAE,2008,24(10):209-213.(in Chinese)

9 QIAN X, SHEN G, WANG Z. Co-composting of livestock manure with rice straw:characterization and establishment of maturity evaluation system[J]. Waste Management, 2014, 34(2):530-535.

10 秦莉,李玉春,李國學,等. 城市生活垃圾堆肥過程中腐熟度指標及控制參數(shù)[J].農(nóng)業(yè)工程學報,2006,22(12):189-194. QIN Li,LI Yuchun,LI Guoxue, et al. Maturity indexes and operational parameters during composting municipal solid waste[J].Transactions of the CSAE,2006,22(12):189-194.(in Chinese)

11 錢曉雍,沈根祥,黃麗華,等. 畜禽糞便堆肥腐熟度評價指標體系研究[J].農(nóng)業(yè)環(huán)境科學學報,2009,28(3):549-554. QIAN Xiaoyong,SHEN Genxiang,HUANG Lihua,et al. An index system for evaluating the maturity of animal manure composting[J].Journal of Agro-Environment Science,2009,28(3):549-554.(in Chinese)

12 李承強,魏源送,樊耀波,等.堆肥腐熟度的研究進展[J].環(huán)境科學進展,1999,7(6):1-12. LI Chengqiang, WEI Yuansong, FAN Yaobo, et al. Advances in study of compost maturity[J].Advances in Environmental Science,1999,7(6):1-12.(in Chinese)

13 KHAN N, CLARK I, SANCHEZ-MONEDERO M A, et al. Maturity indices in co-composting of chicken manure and sawdust with biochar[J]. Bioresource Technology, 2014,168:245-251.

14 SHAN Y N,CHEN J H,WANG L, et al. Influences of adding easily degradable organic waste on the minimization and humification of organic matter during straw composting[J]. Journal of Environmental Science and Health, Part B,2013, 48(5): 384-392.

15 朱青藤,申連玉,錢黎慧,等. 有機物料對白土土壤胡敏酸結(jié)構(gòu)特征的影響[J].植物營養(yǎng)與肥料學報,2015,21(2):396-403. ZHU Qingteng, SHEN Lianyu, QIAN Lihui, et al. Effects of organic material application on the structures of humic acids in low yield paddy soil[J]. Journal of Plant Nutrition and Fertilizer, 2015,21(2):396-403.(in Chinese)

16 竇森，李凱，崔俊濤，等. 土壤腐殖物質(zhì)形成轉(zhuǎn)化與結(jié)構(gòu)特征研究進展[J].土壤學報, 2008, 45(6):1148-1158. DOU Sen, Li KAI, CUI Juntao,et al. Dvancement in the study on formation, transformation and structural characteristics of soil humic substances[J]. Acta Pedologica Sinica, 2008, 45(6):1148-1158.(in Chinese)

17 SHINDO H,YOSHIDA M,YAMAMOTO A, et al. δ13C values of organic constituents and possible source of humic substances in Japanese volcanic ash soils[J]. Soil Science,2005,170(3): 175-182.

18 吳景貴，王明輝，姜亦梅，等．玉米秸稈還田后土壤胡敏酸變化的譜學研究[J]．中國農(nóng)業(yè)科學，2005，38(7):1394-1400． WU Jinggui，WANG Minghui，JIANG Yimei, et al． Study on humic acids in the soil applied with corn stalk by spectroscopy measurements [J]．Scientia Agricultura Sinica，2005，38(7): 1394-1400.(in Chinese)

19 曹瑩菲,張紅,劉克, 等. 不同處理方式的作物秸稈田間腐解特性研究[J/OL].農(nóng)業(yè)機械學報,2016,47(9): 212-219. http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?file_no=20160930&flag=1.DOI：10.6041/j.issn.1000-1298.2016.09.030. CAO Yingfei, ZHANG Hong, LIU Ke, et al. Decomposition characteristics of crop residues among different agricultural treatments [J/OL]. Transactions of the Chinese Society for Agricultural Machinery,2016,47(9): 212-219. (in Chinese)

20 徐硯，朱群益，宋紹國．采用熱重與紅外光譜聯(lián)用研究玉米秸稈熱解[J].熱能動力工程,2012,27(1): 126-129,142. XU Yan，ZHU Qunyi，SONG Shaoguo．Study of the pyrolysis of corn stalk by combining the thermogravimetric method with the infrared spectrum one [J].Journal of Engineering for Thermal Energy and Power,2012,27(1): 126-129,142．(in Chinese)

21 呂程序,姜訓鵬,張銀橋,等.基于變量選擇的小麥粗蛋白含量近紅外光譜檢測[J/OL].農(nóng)業(yè)機械學報,2016,47(增刊): 340-346.http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?file_no=2016s052&flag=1.DOI：10.6041/j.issn.1000-1298.2016.S0.052. Lü Chengxu, JIANG Xunpeng, ZHANG Yinqiao, et al. Variable selection based near infrared spectroscopic quantitative analysis on wheat crude protein content[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2016,47(Supp.):340-346.(in Chinese)

22 鄭曉春,李永玉,彭彥昆,等.基于可見/近紅外光譜的牛肉品質(zhì)無損檢測系統(tǒng)改進[J/OL].農(nóng)業(yè)機械學報,2016,47(增刊):332-339. http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?file_no=2016s051&flag=1. DOI：10.6041/j.issn.1000-1298.2016.S0.051. ZHENG Xiaochun, LI Yongyu, PENG Yankun, et al. Improvement of nondestructive detection system of beef quality based on visible/near infrared spectroscopy [J/OL].Transactions of the Chinese Society for Agricultural Machinery,2016,47(Supp.):332-339.(in Chinese)

23 田海清,應(yīng)義斌,陸輝山,等. 可見/近紅外光譜漫透射技術(shù)檢測西瓜堅實度的研究[J].光譜學與光譜分析,2007,27(6):1113-1117. TIAN Haiqing,YING Yibin,LU Huishan,et al. Study on predicting firmness of watermelon by Vis/NIR diffuse transmittance technique[J].Spectroscopy and Spectral Analysis,2007,27(6):1113-1117.(in Chinese)

24 葛曉雯,王夢,李耀翔.近紅外技術(shù)在土壤化學組分預(yù)測中的應(yīng)用研究綜述[J].森林工程,2013(6):72-76. GE Xiaowen, WANG Meng, LI Yaoxiang. Review on the NIR-based modeling of soil chemical constituents[J].Forest Engineering,2013(6):72-76.(in Chinese)

25 隋世江,葉鑫,雋英華.近紅外光譜技術(shù)在土壤成分檢測中的研究進展[J].農(nóng)業(yè)科技與裝備,2012(1):14-16,19. SUI Shijiang, YE Xin, JUAN Yinghua. Study on application of near infrared spectroscopy in determination of soil components[J].Agricultural Science & Technology and Equipment,2012(1):14-16,19.(in Chinese)

26 LIU F, HE Y. Use of visible and near infrared spectroscopy and least squares-support vector machine to determine soluble solids content and pH of cola beverage [J]. Journal of Agricultural and Food Chemistry, 2007, 55(22): 8883-8888.

27 CEN H, HE Y, HUANG M. Measurement of soluble solids contents and pH in orange juice using chemometrics and vis-NIRS[J]. Journal of Agricultural and Food Chemistry, 2006, 54(20): 7437-7443.

28 黃光群,韓魯佳,樊霞,等.近紅外光譜分析技術(shù)在畜禽糞便堆肥研究中的應(yīng)用[J].中國農(nóng)業(yè)大學學報,2006,11(3):93-97. HUANG Guangqun, HAN Lujia,FAN Xia, et al. Application survey of an archically technique of near infrared spectroscopy on studies of livestock manure compost[J].Journal of China Agricultural University,2006,11(3):93-97.(in Chinese)

29 DOU Z, ZHANG G Y, STOUT W L, et al. Efficacy of alum and coal combustion by-products in stabilizing manure phosphorus[J]. Journal of Environmental Quality,2003,32: 1409-1479.

30 STEVENSON F J. Humus chemistry—genesis,composition,reactions[J]. Journal of Geology,1994, 135(2):129-130.

31 SCOTT D T,MCKNIGHT D M,BLUNT-HARRIS E L, et al. Quinone moieties act as electron acceptors in the reduction of humic substances by humics-reducing microorganisms[J]. Environment Science & Technology, 1998,32(19):2984-2989.

Near Infrared Spectral Modeling Analysis Based on Variable Selection of Compost Humic Acid Content

LI Zigang1,2YUE Xiaoyu1LI Changbin1ZHANG Chunhui2,3WEI Qingbao1LIU Shiliang4

(1.CollegeofPackagingandPrintingEngineering,HenanUniversityofAnimalHusbandryandEconomy,Zhengzhou450011,China2.TheHenanProvincePigEngineeringTechnologyResearchCenterforDiseaseControlandPrevention,HenanUniversityofAnimalHusbandryandEconomy,Zhengzhou450011,China3.TheAustralianAnimalHealthLaboratory(AAHL),Geelong3220,Australisa
4.CollegeofResourcesandEnvironmentalSciences,HenanAgriculturalUniversity,Zhengzhou450002,China)

Composting treatment is a key method of processing organic solid waste, especially for agricultural organic solid waste. Aiming to study the feasibility of several selected variables from near infrared spectroscopy to quantify humic acid in compost, determine composting fermentation and develop corresponding control equipment to provide theoretical basis by near-infrared diffuse reflection spectrum. Totally 100 composting samples were collected, including 58 samples for calibration and 42 samples for validation. On the one hand, the humic acid of these samples were analyzed by using the International Humic Substances Society standard of humic acid method, on the other hand，those were scanned to obtain near infrared spectra with the wavelength range of 4 000～9 000 cm-1. Both of spectroscopic pre-treatment method and sensitive variables were optimized, and then the model was built by partial least squares regression method．The results indicated that humic acid in compost can be determined by near-infrared (NIR) spectral technique, because they were combined with organic groups with NIR absorption. A method for the determination of humic acid in compost samples was established based on the combination of discrete wavelet transform (DWT) and NIR technique. In the proposed method, the raw NIR data and their wavelet coefficients were used for modeling and prediction of the contents of humic acid in compost by partial least square method (PLS). The model based on wavelet coefficients was better than that based on the full NIR spectral range. With the improved method, accurate prediction can be achieved.

composting; quality control; maturity evaluation; humic acid; near infrared spectroscopy; wavelet transform

10.6041/j.issn.1000-1298.2017.02.040

2016-11-20

2016-12-13

國家自然科學基金項目(U1404332)和河南省重點科技發(fā)展計劃項目(112102110034)

李自剛(1970—)，男，副教授，博士，主要從事環(huán)境生物工程技術(shù)研究，E-mail: zigangli@163.com

劉世亮(1970—)，男，教授，博士生導(dǎo)師，主要從事環(huán)境生物工程技術(shù)研究，E-mail: shlliu70@163.com

S24

A

1000-1298(2017)02-0300-05