Losses of nitrate from a sandy loam soil under corn: lysimeter experiment

LOSSES OF NITRA TE FROM A SANDY LOAM SOIL UNDER CORN: L YSIMETER EXPERIMENT. F. Cab e a, A. Reyes, E. Femández-Boy, 1.A. Cayuela. 1.M. Mu illo and F. Mo eno. Ins i u o de Recu sos Na u ales y Ag obiología de Se illa. (CSIC). Apa ado 1052. 41080 Se illa. Addi ional index wo ds: i iga ion, Kjeldahl-N, d ainage wa e , soil wa e con en . Abs ae Losses o ni a e om an undis u bed sandy loam soil con ained in wo monoli h lysime e s, Lo and L¡, (1 m diame e , 1.5 m deep) unde com and i iga ion (628 mm) we e s udied. The c op was e ilized wi h O (Lo) and 800 (L¡) kg N ha-l. Wa e d aining was collec ed pe iodically and analysed o ni a e con en du ing he expe imen al pe iod (20 Ma ch 91-23 Ma ch 92). Mean alues o ni a e concen a ion in he d ainage wa e we e 3.1 and 41.2 mg NO N 1-1 in Lo and Ll espec i ely, he la e much highe han he limi imposed by he EC o po able wa e (11.3 mg N l-I). Th ee pe iods we e dis inguished du ing he expe imen : i) C op season, in which he o al olume o wa e d ained was 310 and 47 mm espec i ely in he Lo and Ll, while he ni a e 10sses we e o he same o de in bo h lysime e s ( 21 and 17 kg N ha- l, espec i ely); ii) D y season, in which he e was no wa e d ainage; and iii) Rainy season, in which he o al d ained wa e was 157 and 139 mm, and he ni a e los ses 5 and 91 kg N ha- l in Lo and L¡ espec i ely. The g ea e amoun o wa e d ained in Lo is due o he lowe c op de elopmen (g ain yield 4.4 and 21.3 ha- l; o al ni o gen plan up ake 69 and 400 kg N ha- l, in Lo and Ll espec i ely). To al ni a e losses in Ll accoun o 13% o he ni o gen e ilize applied. Mos o hese losses occu in he ainy season. A he end o he expe imen al pe iod a dec ease o he soil ni a e con en was obse ed in bo h lysime e s. In oduc ion P oduc ion o hea y yields depends on he use o la ge quan i ies o ino ganic e ilize s, which can imply an en i onmen al isk: he pollu ion o g oundwa e by ni a e. Wha e e o m o ni o gen e ilize is used, he end p oduc in he soil is ni a e, which is ulne able o being washed ou o he soil by ain o i iga ion. The mos decisi e ac o s de e mining he magni ude o ni a e leaching a e ni ogen e iliza ion, c1ima ic condi ions, ype o soil, soil managemen and ype o c op (Gus a son, 1983; Duynis eld e al., 1988; Addisco e al., 1991). Measu emen o ni a e los ses unde ield condi ions is di icul . Fi e me hods o measu ing he concen a ion and luxes o ni a e lea ing he soil we e ou lined by Addisco (1990). A good app oach is he use o monoli h lysime e con aining undis u bed soil (Dowdell e al., 1984; Owen, 1990, Be gs om and Johansson, 1991). The aim o his s udy was o e alua e iming and quan i y o ni a e leaching in a highly e ilized soil unde co n and i iga ion using monoli h lysime e s. These a e p elimina y esul s o a wide s udy las ing ou yea s. 2 Ma e ial and me hods Two monoli h lysime e s (1 m diame e , 1.5 m deep) we e cons uc ed wi hou dis u bing he soil p o ile and eins alled in si u in a plo o 0.1 ha. The soil was a sandy loam XEROCHREPT (pH(H2 0) 7.2 and 7.1; CaCOJ 5.2 and 3.1 %; O.M. 0.88 and 0.69 %; Kje1dahl-N 599 and 454 mg kg-I; NO)-N 7.5 and 10.4 mg kg- I a O-50 and 50-100 cm espee i ely. These a e mean alues o 45 samples). Lysime e s we e p o ided wi h a sys em o collee d ainage wa e (1.2 m deep) and wi h aeeess o neu on p obe. The 1ysime e s we e sown wi h co n (170000 p1an ha- I, 5 Ap il 1991) and e ilized wi h O (Lo) and 800 kg N ha- I (LI ). Fe ilize was applied in h ee s eps: a deep e iliza ion be o e sowing (22 Ma ch 1991) wi h 1000 kg ha- I wi h a 15-15-15 complex NPK e ilize , and wo op d essings wi h 400 kg ha- I (24 May 1991) and 1000 kg ha- I (7 June 1991) o u ea (46 %) espec i ely. Lysime e s we e pe iodically i iga ed (EC 2.0 dS m-I; SAR 2.0 meql l I-I l; NO)-N 10.5 mg 1-1) ecei ing a o al amoun o wa e equi alen o 628 mm. Wa e d aining was collec ed pe iodically and analysed o ni a e du ing he expe imen al pe iod (20 Ma ch 1991-23 Ma ch 1992) ( igu e 1). Ni a e in wa e was de e mined by ionie ch oma og aphy using a mix u e o bo a e-glucona e pH 8.5 as eluen . Soil wa e con en and ain all we e also moni o ed h oughou he expe imen al pe iod ( o al ain al1 equi alen o 293 mm ( igu e 1». Soil samp1es we e collec ed a 0-30,30-60 and 60-90 cm a he end o he expe imen by means o a hin auge . Soil Kje1dahl-N was de e mined by he me hod dese ibed by Hesse (1971). Soil NO N was ex ac ed by 0.2% Ca(OH)z suspension (Sims and Jackson, 1971) and he ex ac s analysed o NO N by he me hod o Scheine (1974). Plan heigh was measu ed pe iodically. Yield, mean weig h o ea s and o al Kje1dah1-N in ke nel we e de e mined a ha es . 3 Resul s and Discussion Volumes o wa e d ained by Lo a e g ea e han hose d ained by L¡, and bo h a e e1a ed wi h he o1umes o wa e supplied by i iga ion and ain all ( igu e 1). The o al eomu1a i e olume o wa e d ained by Lo is also g ea e han ha by L¡ ( igu e 2). Concen a ions o NO N in d ainage wa e anged om <1 o 41.9 and <1 o 155 mg NO)-N 1- 1 espee i ely in Lo and L¡. Thei mean alues we e 3.1 and 41.2 mg NO N I-¡ ( igu e 1), he la e being much highe han he 'maximum admissible coneen a ion' imposed by he EC o po able wa e (11.3 mg NOJ-N 1-1). Th ee seasons can be dis inguished du ing he expe imen al pe iod: i) C op season (20 Ma ch 1991-S Augus 1991; ii) D y season (6 Augus 1991-30 Sep embe 1991); iii) Rainy season (1 Oc obe 1991-23 Ma ch 1992). Du ing he 'c op season' he lysime e s ecei ed a o al o 628 and 55 mm o wa e by i iga ion and ain all espec i ely. In his season· o al wa e d ained was 310 and 47 mm espec i ely in Lo and L1, and o al ni a e losses we e o he same o de in bo h lysime e s (21 and 17 kg NO N ha-¡ espec i ely). Analysing he hyd ic p o iles o he lysime e s du ing he maximun de elopmen o he c op ( igu e 3), i can be obse ed ha on 19 July 1991 (a ew hou s a e he beginning o an i iga ion), wa e con en dec eased h oughou he soil p o ile down o 20 and 70 cm dep h espec i ely in Lo and L¡. A e wa ds wa e con en emained app oxima ely cons an a 0.227±O.OO8 and 0.151±O.004 cm3 cm- 3 (mean±SD) espec i ely in Lo and L¡. Fou days la e (23 July 1991), wa e con en a 0-80 cm in Lo and 0-60 cm in L¡ dec eased compa ed wi h he si ua ion o 19 July 1991, and he shape o he hyd ic p o ile we e simila o bo h lysime e s down o 70 cm dep h. F om 80 cm down in Lo and 70 cm in L¡, wa e con en s we e nea ly cons an , 0.226±O.011 cm3 cm- 3 in Lo and 0.141±O.01 cm3 cm- 3 in L¡, alues simila o hose ound a he same dep h on 19 July. The e o e, du ing his i iga ion e en wa e con en in he soil p o ile o Lo is always g ea e han in ha o L¡. The same si ua ion was obse ed in all he i iga ion e en s h oughou he 'c op season'. As o al olume o wa e d ained was g ea e in Lo han in L¡ ( igu e 2), i is supposed ha wa e deple ion in L¡ is mainly caused by he highe wa e up ake o he c op in his lysime e because o he highe plan de elopmen . In ac , able 1 shows ha co n plan s o L¡ we e olle han hose o Lo, and ha he yield, mean weigh o ea s and o al Kjeldahl-N in ke nel, was also g ea e in L¡. , In he 'd y season' he e was no wa e d ainage and conséquen ly no los ses o ni a e in ei he o he lysime e s. Du ing he ' ainy season', o al wa e d ained in bo h lysime e s was simila , 15Tand 139 mm in Lo and L¡ espec i ely, 66 and 58 % o he o al ain all in his pe iodo Howe e , in he same pe iod ni a e losses in he d ainage wa e we e much highe in L¡ (91 kg NO N ha-¡) han in Lo (S kg N0 3-N ha-¡). Ni a e los ses in L¡ du ing he ' ainy season' we e he 11 % o he N applied as e ilize . To al ni a e leached in L¡ was 108 kg N0 3-N ha-¡, equi alen o 13% o he o al ni o gen applied as e ílize . This quan i y is highe han ha epo ed by C oll and Hayes (60-80 kg NO N ha-¡) o sp ing-sown ce eals, and would be su icien o cons i u e a se ious h ea o he main enance o he EC- ecommended le el in g oundwa e (Fos e e al., 1982). A he end o he ' ainy season' i was ound ha he con en o Kjeldahl-N h oughou he p o ile dec eased in Lo (5733 kg N ha-¡) and inc eased in L¡ (6396 kg N ha-¡) wi h espec o he a e age ini ial con en o he soil (61S7 kg N ha-¡), al hough nei he o he di e ences was s a is ically signi ican (P<0.05) ( igu e 4). A he same ime, ni a e con en in he soil p o ile dec eased signi ican ly (P<Ü.OS) wi h espec o he a e age ini ial con en o he soil (104 kg N0 3-N ha-¡) inbo h Lo (23.8 kg NO N ha- I) and Ll (38.9 kg N0 3-N ha-I) ( igu e 4). Figu e 5 shows a balance o he ni o gen inpu s and ou pu s i i Lo and L¡. I can be obse ed ha a he end o he expe imen al pe lod i was possible o de e mine he a e o mos o he ni o gen o he sys em. In ac , in Lo he di e ence be ween he ini ial and inal s a es (6327 and 5853 kg N hao! espec i ely) was no signi ican (P<0_05) and accoun s o so ne 7% o he ni ogen in he ini ial s a e. In L! o al ni ogen in he ini ial s a e was 7121 kg N hao! and in he inal one 6958 kg: N hao!, he di e ence being non-signi ican (P<Ü.05) and equal o so ne 2% o he ni ogen in he ini ial s a e. These di e ences, hough non-signi ican , can be explained by he inhe en e o o he me hods, losses by ammonia apo iza ion om u ea, by deni i ica ion, o e en by he eleas e o gaseous ni ogen (mainly a nmonia) by he plan s hemsel es. Acknowled~men Resea ch ca ied ou in he amewo k o con ac No. STEP-CT90-0032-C (DSCN) o heCE. Re e ences Addisco , T.M. 1990. Measu emen o ni a e leaching: a e iew o me hods. In: Ni a e-Ag icul u e-Eau (R. Cal e ). INRA. Pa is. Addisco , T.M., Whi mo e, A.P., and Powlson, D.S. 1991. Fa ming, e ilize s and he ni a e p oblem. C.A.B. In e na ional. Walling o d. Be gs om, L, and Johansson, R. 1991. Leaching o ni a e om monoli h lysime e s o di e en ypes o ag icul u al soils_ J. En i on_ Qua!. 20: 801-807. C oll, B.T., and Hayes, C.R. 1988. Ni a e and wa e supplies in he Uni ed Kingdom. En i on. Pollul. 50: 163-187. Dowdell, R.J., Webs e , c.P., Hill, D., and Me ce , E.R.1984. A lysime e s udy o he a e o ni o gen in sp ing ba ley c ops g own on a shallow soil o e lying Chalk: c op up ake and leaching los ses. J. Soil. Sci. 35: 183-190. Duynis eld, W.H.M., S ebel, O, and Bo che , J. 1988. A e ni a e leaching om a able land and ni a e pollu ion o g ound wa e a oidable? Ecol. Bull. 39: 116- 125. Fos e , S.S.D., C ipps, A.C., and Smi h-Ca ing on, A. 1982. Ni a e leaching lo g oundwa e . Phil T ans. Roy. SOCo 18: 103-116. Gus a son, A., 1983. Leaching o ni a e om a able land in o g oundwa e in Sweden. En i on. Geol. 5: 65-71. Hesse, P.R. 1971. A ex book o soil chemis y analysis. John Mu ay Pub. L d. London. Owens, L.B. 1990. Ni a e-ni ogen concen a ion in pe cola e om lysime e s plan ed o a legume-g ass mix u e. J. En i on. Qual. 19: 131-135. Scheine , D. 1974. A modi ied e sion o he sodium salicyla e me hod o analysis o was ewa e ni a es. Wa e . Res. 8: 935-840. Sims, J.R., and Jackson, G.D. 1971. Rapid analysis o soil ni a e wi h ch omo opic acid. Soil Sci. Soco Ame . P oc. 35: 603-606. Table 1 - Mean alues o co n plan heigh and esul s o co n pe o mance a ha es . Lysime e Plan Plan Yield Ea Ke nel heigh heigh 18 Jun 18 Jul mean To al weigh Kjeldahl-N cm cm kgha- 1 g % 70a 136b 218 a 247 b 4415 21295 543 a 187.3 b 1.22 1.53 Values ollowed by di e en le e s in he same column di e signi ican ly (P<O.05). 30 e 20 e ~ 10 111 .... --::::c=- -=-=-,1 200 l'IU'_ -l'lU 150 ; 0~~~~~~~~~--~-40 L - 1 200 z· :'30 ySlme e 1_ wa e 1 1 111 "! .• NOs-N. 150 0" .5 20 • Z 111 '"' " l 10 100 50 El 58 1---- "-...¡~"- -_j::.JII....4I'-......,.-+_'___l O e 40 §30 :;3 11120 bO .í:: 10 .!:: O e 50 8 40 .....;'30 'iii 'j320 .¡¡¡ 10 '"' 0 --'L- -...L. ---,---'~--- lL--' --"""~ O 100 200 300 400 Time (days ( om 20 Ma ch 91) Figu e 1 - D ained wa e , ni a e in d ainage wa e , and i iga ion and ain all da a. El El 400 • 111 e ;:1 'O 300 > 111 > :;¡ 200 '5 e 8 100 OI---'4""""' ----+-+--+-+---+----l '111 120 ..c:: bO ~ 100 Z 1., 80 O Z 111 60 > :;1 I l '5 40 8 ;:1 U 20 Ni a e losses • Lysime e o o Lysime e 1 OL- __ E......-L.._-'-----'-_...L----L---.J O 100 200 300 400 Time (days ( om 20 Ma ch 91) Figu e 2 - Cumula i e olume o d ained wa e and cumula i e ni a e losses. 3 -3 wa e con en , cm cm 0.0 0.1 0.2 0.3 0.4 0.5 O -'-- -'--~- ~-- -,-- -, • LO 19 JUL .. LO 23 JUL o L1 19 JUL L1 23 JUL 90 Figu e 3 - Hyd ic p o iles o he lysime e s. . 140 D ini ial lS:Sl inal LO 120 ~ inal L1 C.L. 95% 100 i' < i 80 .c: C.L. 95% ~60 40 20 O L-~~~~L-_~2~-L~~~--~ Kjel.-Nxl0 N0 3 -N Figu e 4 - Con en s o Kjeldahl-N and N0 3-N in he soils o he wo lysime e s. mm! soil N03 -N n soil Kjeldahl-N _ i . wa e N03 -N ~ plan up ake N D e ilize N s:s:J d ainage wa e N03 -N «3 .. :::: :ID .!S: 10000 5000 1000 Z 500 O ini ial inal (Ti i I L . O inilial inal s a e s a e • III1111 Figu e 5 - Ni ogen balance.