Annex 5: Preliminry Results from the Soil Incution Study/Pot Experiment on Fertilizer Vlue of Aneroiclly Digested Slurries from Cofermenttion with Ulv lctuc Henrik Hugrd-Nielsen, Senior Resercher. E-mil: hnie@risoe.dtu.dk Dorette Müller-Stöver, Post Doc. E-mil: dsst@risoe.dtu.dk Risø DTU, Biosystems Division
1 Preliminry Results from the Soil Incution Study/Pot Experiment on Fertilizer Vlue of Aneroiclly Digested Slurries from Co-fermenttion with Ulv lctuc Ojectives of the Study The ojectives of the study were: 1) to determine the fertilizer vlue of the effluents originting from cttle mnure co-digested with Ulv lctuc in comprison to the neroiclly digested cttle slurry lone 2) to investigte the potentil greenhouse gs emissions (N 2 O, CO 2 ) fter ppliction of the different slurries nd 3) to otin informtion out key soil processes underlying the oserved effects. To chieve these ims, pot experiment with rley plnts nd soil incution study were set up simultneously. The incution study ws used to intensively follow the evolution of greenhouse gses nd key soil processes during the first three weeks fter incorportion of the different soil mendments, while the pot experiment ws ment to give indiction of the longer-term plnt response to the effluents. Mterils nd Methods Soil Used The soil selected for the incution study nd the pot experiment ws tken from the -25 cm lyer of n griculturl field t Risø DTU (55 41 N, 12 5 E) with 11% cly, 14% silt, 49% fine snd, nd 25% corse snd (Typic Hpludlf). The soil ws ir-dried nd sieved to otin the frction 1 cm. Incution Study The experiment ws crried out using 2 g dry soil, incuted in 33 ml PVC continer. Before the strt of the incution, the soil ws wetted nd pre-incuted t room temperture for 14 dys.
2 Seven different sustrte tretments hve een set up: Soil 2 g (CO) Soil 2g + minerl fertilizer (MIN) Soil 2g + wet Ulv lctuc (UW) Soil 2g + dried nd ground Ulv lctuc (UD) Soil 2 g + iogs effluent from cttle mnure (SL) Soil 2 g + iogs effluent from co-digested cttle mnure with Ulv lctuc (2%, SL UL) Soil 2 g + iogs effluent from co-digested cttle mnure with Ulv lctuc (4%, SL UH) The different mendments were dded t rtes to provide 3 mg totl N per kg dry soil nd mixed thoroughly into the soil. The minerl fertilizer ws dded in solution of mmoniumnitrte nd potssiumdihydrogenphosphte (2 mg P/kg dry soil nd 3 mg K/kg dry soil) s well s mgnesiumsulfte (2 mg Mg/kg dry soil). The mount of wter dded ws djusted to rech WFPS of 65%. Ech individul continer ws seled with pierced lid, nd the soil moisture content ws kept constnt during the experiment. The continers were incuted t constnt 21 C in thermo cinet throughout the 23 dys experiment. Pot Experiment The pot experiment comprised the sme tretments s the incution study. All mendments were thoroughly mixed to 2 kg soil (dry weight sis) which ws then filled in lck plstic pots (height 17 cm, dim. 15 cm, volume 3 l). Eight spring rley seeds (cv. Power) were sown per pot nd plnts were thinned to four per pot fter emergence. The pots were set in growth chmer with 21 C/16 C dy/night nd 16 h dy length nd irrigted s required. Greenhouse Gs Anlyses Cron dioxide nd N 2 O emissions were mesured on dys 2, 3, 4, 5, 8, 1, 12, 15, 18, nd 22 during the incution. The continer lids were opened nd ech continer ws plced in 2 l gs-tight glss jr. Gs ccumultion in the hedspce ws mesured using Photocoustic Field Gs-Monitor (INNOVA 1412 Photocoustic Field Gs Monitor,
3 LumSense Technologies, Bllerup, DK) equipped with three individul opticl filters (CO2, N2O nd wter vpor), connected in closed loop to the glss jr vi two vlves mounted in the lid nd side of the jr, respectively. Hedspce concentrtions were mesured pproximtely, 3, 6, nd 9 min. fter closing the jrs nd flux rtes were clculted using liner regression. Linerity of emissions ws lwys tested nd only mesurements with sttisticlly significnt regressions or n R 2.95 were tken into ccount. Soil Anlyses Destructive soil smplings were performed on dys 1, 8, 23 for the incution study nd dy 1, 23 nd 59 for the pot experiment. Ten g of soil smple were extrcted with 5 ml.5 M K 2 SO 4 for 6 min nd the extrcts were filtered through pleted filters (Grde 74, Frisenette Aps, Denmrk). Concentrtions of mmonium (NH 4 +) nd nitrte (NO 3 -) were determined colorimetriclly. Dissolved orgnic cron (DOC) ws extrcted y the sme procedure nd nlyzed on TOC-VCPH (Shimdzu). Another set of susmples (1g) ws vcuum-incuted with chloroform for 24 efore extrction to determine microil iomss C nd N (Vnce, et l., 1987). The iomss C ws mesured from the reltionship C iomss =2.22 x EC, where EC is [DOC fumigted ]-[DOC unfumigted ] (Wu, et l., 199). The iomss N ws mesured from the reltionship N iomss =1,85 x EN, where EN is [TDN fumigted ]-[TDN unfumigted ] (Joergensen nd Mueller, 1996). Soil ph ws determined in 5:25 (w/v) suspension of fresh soil in distilled wter. 1 g of fresh soil were extrcted with 5 ml Milli-Q wter (gitted 6 min) followed y filtrtion. The orgnic cron pool mesured in the extrct, using Shimdzu TOC-VCPH nlyzer (Shimdzu Corp., Kyoto, Jpn), is referred to s cold-wter-extrctle cron (CWEC). Plnt-ville phosphorus (Olsen-P) ws mesured fter extrction of 2 g fresh soil with 3 ml NHCO 3 (ph 8.5) y stndrd colorimetric procedures on n AutoAnlyzer 3 (Brn+Luee, Norderstedt, Germny).
4 Plnt Anlyses Plnt dry mtter per pot ws recorded twice, fter three weeks (together with the lst destructive soil smpling of the incution continers) nd t the end of the experiment. The dried mteril ws ground nd nlysed for its totl N content using n EA-111 CHN elementl nlyzer (CE instruments, Miln, Itly). The P uptke ws clculted fter wet digestion of the plnt mteril nd nlysis of the P content s descried ove. Preliminry Results Plnt Response in the Pot Experiments The plnt dry mtter recorded ws very similr mong ll tretments t oth hrvest dtes (21 nd 59 dys fter sowing, Figure 1). Only the tretment receiving minerl fertilizer resulted in significntly incresed dry mtter production, wheres ll other soil mendments only cused slight, insignificnt increse in dry mtter compred to the untreted control. 9 8 21 DAS 59 DAS 7 Plnt dry weight (g) 6 5 4 3 2 1 CO MIN UW UD SL SL UL SL UH Figure 1: Plnt dry weight in the pot experiment t two different hrvest dtes. DAS= dys fter sowing. CO=non-mended control soil, MIN= soil + minerl fertilizer, UW = soil+wet U. lctuc, UD=Soil+dried nd ground U. lctuc, SL= soil+iogs effluent from cttle mnure, SL UL= Soil+iogs effluent from co-digested cttle mnure with U. lctuc (2%); SL UH=Soil+iogs effluent from co-digested cttle mnure with U. lctuc (4%). Brs with different letters within the sme smpling dtes re not significntly different t p,5.
5 Plnt Nutrients in Soil in Incution nd Pot Experiment The minerl N concentrtion in the soil t the eginning of the experiment ws similr in oth the minerlly fertilized tretment nd in the tretment receiving digested cttle mnure (Figure 2). 6 1 21 59 DAS 5 mg minerl N/kg dry soil 4 3 2 1 CO MIN SL UW UD SL UL SL UH Figure 2: Concentrtion of soil minerl N in the pot experiment t different smpling dtes. DAS= dys fter sowing. CO=non-mended control soil, MIN= soil + minerl fertilizer, UW = soil+wet U. lctuc, UD=Soil+dried nd ground U. lctuc, SL= soil+iogs effluent from cttle mnure, SL UL= Soil+iogs effluent from codigested cttle mnure with U. lctuc (2%); SL UH=Soil+iogs effluent from co-digested cttle mnure with U. lctuc (4%). Brs with different letters re not significntly different t p,5. The tretments tht received slurry from co-digestion with Ulv showed lower levels of minerl N t the eginning of the experiment especilly when the proportion of Ulv in the slurry ws high. However, in the soil incution experiment similr levels of minerl N in ll slurry tretments (36-39 mg/kg dry soil) were detected fter 8 dys, indicting high N minerliztion potentil from the slurries contining Ulv. At the first hrvesting dte, minerl N concentrtion in soil ws lredy very low in ll pots, eing only mrginlly higher in the slurry tretments. The differences in plnt dry mtter etween CO nd the Ulv tretments on the one side nd the minerlly fertilized tretment on the other could therefore e well
6 explined y initil differences in soil minerl N content. However, the oserved differences in dry mtter etween the slurry tretments nd the minerlly fertilized tretment re not s ovious to interpret, ut will proly e clrified fter determintion of the plnts N uptke. Plnt-ville phosphorus in the soil my hve een nother fctor limiting plnt growth in the orgniclly fertilized tretments (Figure 3), since initil Olsen-P ws only incresed in the minerlly fertilized tretments compred to the non-treted control. A decrese of plntville phosphorus (proly y plnt-uptke) during the first three weeks could e oserved in ll tretments, ut ws pprently much greter in the MIN tretment thn in the orgniclly mended soils. 4 35 1 21 59 DAS mg Olsen-P/kg dry soil 3 25 2 15 1 5 CO MIN SL UW UD SL UL SL UH Figure 3: Concentrtion of Olsen-P in the pot experiment t different smpling dtes. DAS= dys fter sowing. CO=non-mended control soil, MIN= soil + minerl fertilizer, UW = soil+wet U. lctuc, UD=Soil+dried nd ground U. lctuc, SL= soil+iogs effluent from cttle mnure, SL UL= Soil+iogs effluent from co-digested cttle mnure with U. lctuc (2%); SL UH=Soil+iogs effluent from co-digested cttle mnure with U. lctuc (4%).
7 Greenhouse Gs Emissions in the Soil Incution Study µg N 2 O-N/g dry soil 2 1,8 1,6 1,4 1,2 1,8,6,4,2 CO MIN SL UW UD SL UL SL UH 1 2 3 4 5 8 1 12 14 18 22 Dys of incution Figure 4: N 2 O emissions during soil incution. CO=non-mended control soil, MIN= soil + minerl fertilizer, UW = soil+wet U. lctuc, UD=Soil+dried nd ground U. lctuc, SL= soil+iogs effluent from cttle mnure, SL UL= Soil+iogs effluent from co-digested cttle mnure with U. lctuc (2%); SL UH=Soil+iogs effluent from co-digested cttle mnure with U. lctuc (4%). N 2 O emissions were clerly correlted to the minerl N-content of the different soil mendments, eing highest in the minerlly fertilized tretment nd lowest in the nonmended control nd pure Ulv tretments (Figure 4). No differences etween the three types of digested slurries were detected. Due to errtic CO 2 mesurements t the lst smpling dtes, CO 2 emissions re shown only for the first two weeks (Figure 5). They neither differed etween tretments, except for the tretment tht received the dried Ulv lctuc powder which cused significntly higher CO 2 evolution compred to ll other tretment except SL. The reson for tht cn only e speculted out, ut might e high content of esily degrdle orgnic mtter in the dried lge. The soils without orgnic mendment (CO nd MIN) hd correspondingly the lowest CO 2 emissions. Agin, no significnt differences etween the different slurry types occurred.
8 µg CO2-C/g dry soil 7 6 5 4 3 2 CO MIN SL UW UD SL UL SL UH 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 Dys of incution Figure 5: CO 2 emissions during soil incution. CO=non-mended control soil, MIN= soil + minerl fertilizer, UW = soil+wet U. lctuc, UD=Soil+dried nd ground U. lctuc, SL= soil+iogs effluent from cttle mnure, SL UL= Soil+iogs effluent from co-digested cttle mnure with U. lctuc (2%); SL UH=Soil+iogs effluent from co-digested cttle mnure with U. lctuc (4%). Preliminry Conclusions The co-digestion of U. lctuc together with cttle mnure did not lter the overll fertiliztion vlue nd GHG emission potentil of the digestte. However, some deeper insights in plnt nutrient uptke nd soil nutrient dynmics (including soil microil iomss) re expected when ll dt re nlysed.