This study explored the application of compost onto a small loblolly pine tree forest in northeast Texas. Its purpose was to determine if the application of various amounts of compost would provide for accelerated rates of growth for the trees. Soil parameters were also monitored. A total of 270 trees were planted and studied in a northeast Texas forest ecosystem. Compost rates of 5, 25, and 50 tons per acre with either soil or compost backfill were utilized and compared to a control without compost. Nonparametric and parametric ANOVA and Chi-Square tests were utilized. The results indicated that greater application rates retained greater moisture and higher pH levels in the soil. Compost applications also yielded a greater survival rate as well as larger tree height and diameter when compared to the control. The 25 ton/acre application backfilled in native soil achieved the greatest average in height and diameter when compared to the averages for the control plot. Greater growth differences for the 25S application can be attributed to additional nutrients coupled with a stable pH consistent with native soil acidity.

Biochar, the solid product of thermal conversion of biomass with little or no available air, is acknowledged as a carbon dioxide removal technique and soil enhancer among other applications. Its potential soil enhancing properties consists of increased water and nutrient holding capacities, liming effects and sorption of pollutants. However, not all soils benefit equally from biochar amendments. The thesis aims to investigate the suitability of biochar applications to agricultural soils in Sweden and communicate the results visually with a biochar indication map, illustrating where biochar could serve the highest benefits as a soil improver. A literature review was carried out to analyse the soil enhancing opportunities of biochar applications, which determined that the criteria soil texture, nitrogen leaching, ground moisture, soil pH and soil organic matter (SOM) were suitable for the analysis in a Swedish context. Then, a multi-criteria analysis was conducted in ArcGIS, based on spatial data of these criteria. Each arable land block was assigned a biochar class, varying from high indication to no indication. Arable land was considered highly recommended for biochar applications if the soil texture was sandy and at least one of the soil criteria was beyond a limiting agronomic threshold. At the national level, high indication for biochar application occupied 24.2% (528 thousand ha) of the arable land in Sweden, while the remaining land had either medium indication (13%), low indication (3.5%) or no indication (59.3%). Despite spatial variations, all Swedish counties (with data coverage above 84%) had at least 2% of high indication arable land. In particular, 66.1% of Halland’s arable land showed high indication. In turn, Skåne had the largest area (148 thousand ha, 35.7%) with high indication for biochar applications. The corresponding biochar volume potential, at the national level, suggested that between 0.5 and 26.4 million tonnes biochar can be applied to arable land with high indication for biochar applications, given application rates between 1 and 50 tonnes/ha over a 20 year timeframe. This means that arable land in Sweden can accommodate for a future production of 500 000 tonnes per year, which was suggested as an upper limit in an inquiry from the Swedish government, if application rates remain below 20 tonnes/ha. The multi-criteria analysis performed includes several subjective choices and uncertain parameters (criteria combination, data accuracy, agronomic thresholds, and classification scheme). Therefore, the biochar indication maps cannot yet be used for farm- or field-level recommendations for biochar applications. Nonetheless, despite uncertainties, the national- and county- level indication maps may still provide interesting order of magnitude. More field experiments are needed in Sweden as well as a more detailed analysis. To be able to make more precise recommendations, the present analysis can be refined by connecting all criteria to physical agricultural mechanisms and to the properties of biochar, and by using spatial data with higher resolution or even field-level data. This said, models need to be validated with experimental data, which is to date, non- existent: controlled biochar field experiments are therefore needed in Sweden. / Biokol, en solid produkt från termisk omvandling av biomassa med begränsat syre tillgängligt, är identifierad som en möjlig teknik för att minska halten av koldioxid i atmosfären och som jordförbättrare bland andra applikationer. Dess potentiella jordförbättrande egenskaper består av vattenhållning, näringsbindning, balansering av pH-värdet och minskad biotillgänglighet av föroreningar. Däremot så drar inte alla jordar samma nytta av biokolapplikationer. Arbetet syftar till att undersöka lämpligheten av biokolapplikationer på jordbruksmark i Sverige och kommunicera resultaten visuellt med en indikationskarta. En litteraturstudie genomfördes för att analysera jordförbättringsmöjligheterna till följd av biokolsapplikationer. Det fastställdes att kriterierna jordtyp, kväveläckage, markfuktighet, pH och organiskt material var lämpliga för analys i svensk kontext. En multikriterieanalys utfördes i ArcGIS, baserat på rumsliga data för dessa kriterier. Vardera jordbruksblock tilldelades en biokolklass, som varierade mellan hög indikation och ingen indikation. Jordbruksmark ansågs högt rekommenderad för biokolapplikationer om jordtypen var av sandig karaktär och minst ett av kriterierna översteg ett begränsande tröskelvärde. På nationell nivå ockuperade hög indikation för biokolapplikationer 24.2% (528 tusen hektar) av Sveriges jordbruksmark, medan den återstående marken hade antingen måttlig indikation (13%), låg indikation (3.5%) eller ingen indikation (59.3%). Trots rumsliga variationer, hade samtliga svenska län (med datatillgänglighet över 84%) minst 2% åkermark med hög indikation. I synnerhet, 66.1% av Hallands åkermark visade hög indikation. Vidare, Skåne hade den största arealen (148 tusen hektar, 35.7%) med hög indikation för biokolapplikationer. Den motsvarande potentialen för biokol, på nationell nivå, antyder att mellan 0.5 och 26.4 miljoner ton biokol kan appliceras på jordbruksmark med hög indikation för biokolapplikationer, givet appliceringsgrader mellan 1 och 50 ton/hektar över en 20-årsperiod. Detta innebär att svensk jordbruksmark kan rymma en framtida produktion på 500 000 ton per år, förslaget av en statlig utredning, ifall appliceringsgraden förblir under 20 ton/ha. Den utförda multikriterieanalysen inkluderar flertalet subjektiva val och osäkerheter (kriteriakombination, datans noggranhet, tröskelvärden, och klassificeringsmetod). Därmed kan indikationskartorna för biokol ännu inte användas för rekommendationer på jordbruksblocknivå. Resultaten kan emellertid, trots osäkerheter, antyda intressanta storleksordningar på nationell- och länsnivå. Fler svenska fältexperiment samt en mer detaljerad analys behövs. För att kunna ge mer exakta rekommendationer, kan den nuvarande analysen utvecklas genom att koppla samtliga kriterier till fysiska jordbruksmekanismer och biokolsegenskaper och genom att tillämpa rumsliga data av högre upplösning eller till och med fältnivådata. Modeller måste valideras med experimentella data, som hittills är obefintlig: kontrollerade fältförsök med biokol behövs därmed i Sverige.