合肥市绿地土壤氮磷有效性特点

以合肥市典型道路、公园和庭院绿地土壤为对象,测定分析了绿地土壤理化性状和氮磷有效性特点。结果表明,绿地表层土壤容重平均值为1．45g／cm^3,总孔隙度为43．6％;土壤电导率平均值为159μ S／cm;pH值多在7．5～8．5,碱性化明显。老城区土壤氮磷有效性显著高于政务新区,老城区表层土壤全氮和速效氮含量的平均值分别为1．38g／kg和4．52mg／kg,高出政务区18．9％和42．1％;全磷和速效磷分别为1009．3mg／kg和41．9mg／kg,分别是政务区的3．0和1．9倍。园林绿地土壤具明显的富磷特征。     

Reclamation of Alkali Soils: Influence of Amendments and Leaching on Transformation and Availability of Phosphorus

Abstract

Phosphorus (P) availability to plants in reclaimed alkali soils was the main objective of this study, which was also focused on P transformations, decrease in Olsen‐P content, and magnitude of P lost in leachate in course of amendment application and leaching. Liquid sodium bicarbonate (NaHCO₃) was added to nonalkali soils to set up four ESP (exchangeable sodium percentage) levels (viz., 2.9, 25.0, 50.0, and 75.0), but actual ESP levels obtained were 2.9, 24.6, 51.2, and 75.3. Amendments (viz., gypsum and pyrites) and P treatments (viz., 0 and 50 mg P Kg^?1) were mixed with dry, sieved soil before filling into PVC (polyvinyl chloride) drainage columns, which were then compacted to uniform bulk density and leached with deionized water for 30 days. Results indicated that the pH and electrical conductivity (EC) of the soils increased with increase in ESP level of the soil but decreased with amendment application. Phosphorus addition to alkali soils decreased the pH on day 30, but it could not affect the EC of the soils. Successive increase in the ESP level of the soil increased the pH and EC off the leachate. Gypsum‐amended soils exhibited lower pH and EC values than pyrite‐amended soils. The EC of the leachate decreased sharply with time in amended soils, but the pH decreased slowly. Phosphorus addition affected the leachate pH earlier than the soil pH. Cumulative volume of leachate decreased with increasing ESP levels, but it increased with amendment and phosphorus application. Leaching of P increased with increase in ESP levels, and the maximum cumulative loss of P was 11.2 mg Kg^?1 in the 75.3 ESP soil. Cumulative P lost in the pyrite‐amended soils was higher than the gypsum‐amended soils. Phosphorus leaching in the gypsum‐amended soils stopped at day 10 and beyond, but it continued until day 30 in the pyrite‐amended soils. Part of the applied P in alkali soils was also lost along with the native P, whereas it was protected in the nonalkali soils. OlsenP increased with increasing ESP levels, and alkali soils invariably contained higher Olsen P than nonalkali soils. At day 30, alkali soils contained much higher Olsen P (12.6 mg Kg^?1) than nonalkali soils (5.9 mg Kg^?1). In general, there was a decrease in the Olsen P with both of the amendments, but it decreased more with pyrites than with gypsum. Phosphorus added through monopotassium phosphate (KH₂PO₄) remained extractable by Olsen's extractant up to day 30. Results also indicated that percent distribution of ammonium chloride (NH₄Cl)‐P, calcium (Ca)‐P, and unknown P increased with rising ESP levels but iron (Fe)‐aluminum (Al)‐bound P and residual P decreased. Percent distribution of Ca‐P and unknown P exhibited an increase with time also. Unamended alkali soils contained more NH₄Cl‐P than amended ones. Iron and Al‐ bound P and residual P increased more with pyrites, whereas formation of Ca‐P and unknown P was enhanced with gypsum. Applied P tended to convert more into NH₄Cl‐P, Ca‐P, and residual P than to Fe‐Al‐bound P or unknown P fractions. Models developed to estimate Olsen P and P concentration in leachate, through pH or EC, have application value for P management in alkali soils that are leached after application of amendments.     

Phosphorus Availability in Soils Amended with Different Phosphate Fertilizers

Abstract

Accurate measurement and characterization of phosphate rock dissolution are important for a better understanding of phosphorus (P) availability in soils. An incubation study was carried out on two New Zealand topsoils (0–15 cm; high P buffering capacity Craigieburn and low P buffering capacity Templeton) amended with North Carolina phosphate rock (NCPR) and water‐soluble phosphate (WSP) at 218 mg P kg^?1 (equivalent to 60 kg P ha^?1). Isotopic exchange kinetics was carried out after 12 h and 28 days of incubation to characterize P availability. This study showed that sensitivity of capacity factors (r₁/R, n) to explain changes in E_1min values was affected by the P buffering capacity of the soils. The recovery of applied P in the E pool (Rec_inE%) with extended incubation time was similar from the NCPR and WSP treatments (3.1–3.3%) in the Craigieburn soil compared with the Templeton soil in which Rec_inE% values were greater in WSP (9%) than NCPR (1.3%) treatment. The higher values of P derived from the applied P fertilizers in the E pool (Pdff_inE%>80%) suggested that the NCPR application in both soils would be efficient for increasing P availability to plants.     

Nitrogen and Phosphorus Availability in Groundfish Waste and Chitin-Sludge Cocomposts

Seafood processing generates a substantial volume of wastes. This study examined the feasibility of converting the fish waste into useful fertilizer by composting. Groundfish waste and chitin sludge generated from the production of chitin were composted with red alder or a mixture of western hemlock and Douglas-fir sawdust to produce four composts: alder with groundfish waste (AGF); hemlock/fir with groundfish waste (HGF); alder with chitin sludge (ACS); and hemlock/fir with chitin sludge (HCS). The resulting AGF had a higher total N and a lower C:N ratio than the other three composts. A large portion of the total N in the AGF, HGF, and HCS composts was in inorganic forms (NH₄⁺-N and NO₃^?-N), as opposed to only two percent in the ACS compost. Alder sawdust is more quickly decomposed, which favored N retention and limited nitrification during the composting period. It was less favorable than the hemlock/Douglas fir sawdust for composting with chitin sludge. Corn growth on soil amended with compost was dependent upon both compost type and rate. Nitrogen and P availabilities in all composts except the ACS were high and compost addition enhanced corn yields, tissue N and P concentrations, and N and P up-take. Neither the total N concentration nor the C:N ratio of the composts was an effective measure of compost N availability in the soil. Because soil inorganic N test levels correlated well with the corn biomass, tissue N and N uptake, they should be an effective measure of the overall compost effects on soil N availability and corn growth response. Phosphorus concentration, which increased linearly with increasing compost rates, was related to soil P availability from compost additions and correlated well with corn biomass, tissue P concentration and P uptake under uniform treatments of N and K fertilizers. Composting groundfish waste with alder or hemlock/Douglas-fir sawdust can produce composts with sufficient amounts of available N and P to promote plant growth and is considered to be a viable approach for recycling and utilizing groundfish waste.     

酸化与富磷对农田土壤硅有效性的影响

目前，大量农田土壤及其生态功能正经受着土壤酸化的严重威胁，而土壤pH深刻影响着土壤中硅、磷养分的移动性及两者间的相互作用。关于硅肥施用可有效提升土壤磷素植物有效性的研究已有大量报导，但在农业集约化生产区，土壤磷素已大量累积的背景下，磷富集对土壤硅移动性与有效性的影响及其机制尚不清楚。选取2种不同有效硅水平的农田土壤（低有效硅土壤LASi：有效硅28.20 mg?kg-1；高有效硅土壤HASi：有效硅253.6 mg?kg-1），通过等摩尔浓度硅磷竞争吸附试验、土壤培养试验等，探究人工酸化与磷添加对土壤硅吸附性能与移动性的影响及其机制。结果表明，酸化土壤pH在3.5~8.0范围内，当硅与磷等摩尔浓度同时添加时，磷的存在会降低硅的吸附，各相应pH的LASi与HASi 2种土壤对硅的吸附量分别降低26%~74%、31%~84%。这说明，土壤对磷的吸附大于对硅的吸附。设置土壤pH3.5~8.0范围内，降低pH可降低土壤对硅的吸附；磷添加降低土壤硅吸附的效应，在高pH条件下更为显著。土壤酸化与磷添加降低了土壤对硅的吸附，降低了土壤有效硅（HOAc-NaOAc-Si）水平；不同类型土壤移动性硅（CaCl2-Si）水平对酸化与磷添加的响应不同，具体机理尚需进一步研究。     

Phosphorus Availability in Lolium perenne L. in Acidic and Limed Soils

Soil liming may increase phosphorus (P) availability, but this increase may also be achieved with generous P applications. However, it is not well known which practice has longer-term effects. Thus, in a pot experiment, an acidic soil (pH 4.57), limed to pH 6.5, was added with P and sown with Lolium perenne L. We conducted three cuttings (on Days 40, 80, and 120) in order to evaluate P dynamics in each of the treatments. As expected, biomass increased significantly with liming. We also found that plant P concentration increased in the liming treatment, but not in the P-added treatment, although the difference was reduced on Day 120. This shows that in severely acidic soils, liming should be preferred over P addition, although the beneficial effects may not last for a very long time, since in this experiment, they only lasted for 4 months. Similar conclusions were drawn from soil P extraction results.     

Effect of Submergence on Iron Transformation and Phosphorus Availability in Calcareous Soils

A thermostatic incubation experiment was carried out to estimate the effects of flooding periods,stalk application and P addition of Fe transformation and P availability in calcareous soils.Submergence increased amorphous Fe,especially in the case of stalk application.The newly formed amorphous Fe with a great surface area played an important role in Psorption;and submergence also stimulated the dissolution of inorganic P,thus increasing the availability of soil P in calcareous soils.Meanwhile,a part of soluble P was absorbed and fixed again on the surface of newly formed amorphous Fe,thus resulting in a decrease of P availability.Soil rapidly available P increased after 150-day incubation.There existed significantly negative correlations between soil amorphous Fe content and soil Fe-P and rapidly available P contents.Submerged conditions promoted the transformation of inorganic P added toward Fe-P in calcareous soils,especially in the case of stalk application.     

长期施肥对酸性土壤磷形态及有效性的影响

为明确长期施肥对集约化果园土壤磷形态、分布特征及其有效性的影响，本研究对琯溪蜜柚主产区29个果园的土壤进行调查研究，采用张守敬和Jackson的酸性土壤无机磷分级方法，研究蜜柚果园土壤磷素累积对土壤磷形态及有效性的影响。结果表明：在集约化蜜柚果园中，土壤磷素累积丰富，随树龄增加土壤速效磷含量上升显著，且土壤磷形态在不同土层存在显著性差异；当全磷含量≤0.5 g/kg时，土壤磷形态主要以有机磷、铁磷为主，随着全磷含量的上升，铝磷含量、占比均显著上升；多元线性回归和逐步回归分析结果表明本试验中铝磷与速效磷相关性最好。果园土壤已经形成一个巨大的磷库，且有效性较高，可适当减少磷肥投入，降低土壤磷含量，减少经济成本，提高生态效益。     

连续淋洗对山东省主要土壤磷素有效性及磷库的影响

研究采取室内模拟降雨淋洗的方法,研究了连续淋洗对山东省3大土类磷素有效性和磷库的影响。结果表明,3种土壤的磷淋失量均随着供磷水平的提高而升高。3种土壤出现磷淋失量峰值的时间有着明显差异,褐土施磷处理的磷淋量峰值分别出现在第3 d,4 d和5 d;而潮土高磷和低磷处理的磷淋洗最高值分别出现在第2 d和3 d;而棕壤不同施磷处理的磷淋洗高峰值均出现在第2 d。在相对较低的施磷水平下(P3以下),3大土类的速效磷含量基本均保持在20μg/g左右,再提高供磷水平,褐土和棕壤的土壤速效磷含量随施磷量的增加显著升高,而潮土的速效磷含量则随着施磷量的增加先升高后降低。在3大土类中,全磷含量最高的是褐土,其次是潮土,再次是棕壤。在淋洗条件下,褐土的土壤磷库相对变化不大,而潮土和棕壤的磷库则随施磷量的变化有着较大的起伏。因此,施磷水平控制在P3水平(180 kg P/hm2),3大土壤的磷淋失量较低,土壤速效磷变化不大,有利于减少土壤磷素淋失到水体的风险,也保证了土壤磷的供应能力。     

连续淋洗对山东省主要土壤磷素有效性及磷库的影响

研究采取室内模拟降雨淋洗的方法,研究了连续淋洗对山东省3大土类磷素有效性和磷库的影响。结果表明,3种土壤的磷淋失量均随着供磷水平的提高而升高。3种土壤出现磷淋失量峰值的时间有着明显差异,褐土施磷处理的磷淋量峰值分别出现在第3 d,4 d和5 d;而潮土高磷和低磷处理的磷淋洗最高值分别出现在第2 d和3 d;而棕壤不同施磷处理的磷淋洗高峰值均出现在第2 d。在相对较低的施磷水平下（P3以下）,3大土类的速效磷含量基本均保持在20μg/g左右,再提高供磷水平,褐土和棕壤的土壤速效磷含量随施磷量的增加显著升高,而潮土的速效磷含量则随着施磷量的增加先升高后降低。在3大土类中,全磷含量最高的是褐土,其次是潮土,再次是棕壤。在淋洗条件下,褐土的土壤磷库相对变化不大,而潮土和棕壤的磷库则随施磷量的变化有着较大的起伏。因此,施磷水平控制在P3水平（180 kg P/hm^2）,3大土壤的磷淋失量较低,土壤速效磷变化不大,有利于减少土壤磷素淋失到水体的风险,也保证了土壤磷的供应能力。     

Measurement of in situ Phosphorus Availability in Acidified Soils using Iron-Infused Resin

A hybrid anion resin was tested for in situ phosphorus (P) availability measurement in soils of two stands recovering from acidification and having different P-sorption characteristics. The phosphate (P-PO₄) sorption capacity of the resin (before saturation) was 48 µmol g^?1. Sorption and elution were tested under P-PO₄ concentrations common in acidic soils (0–0.42 mmol l^?1) either with or without the presence of sulfate (0.2 mmol l^?1). The efficiency of P-PO₄ sorption was independent of the sulfate and was 100 ± 0.2% (n = 56, ± SD). The P-PO₄ recovery stabilized after six elution steps (each: 50 ml of 0.5 M sodium hydroxide, resin/solution 5:1). The efficiency of P-PO₄ recovery was 80 ± 7% and was used to evaluate field measurements. We determined the amount of P-PO₄ in the field using resin bags in three consecutive years. The results indicate that bioavailable P is negatively related to the soil ability to retain P.     

Phosphorus Availability as Influenced by Organic Residues in Five Calcareous Soils

The use of organic residue is appropriate in maintaining long-term phosphorus (P) requirement of crops. This study was conducted to investigate the effect of time and organic residue addition on P availability in some calcareous soils. Five plant residues and two manures in a wide range of C/N ratios were added to the soil samples at rates of 20 g kg^?1 soil. The samples were incubated for 2, 72, 336, 672, 1440, and 2160 hours at constant temperature and moisture. Extractable phosphorus (Olsen-P) was determined after the incubation. There were decreases in the Olsen-P in all five amended soils during 2160 hours of incubation. The power model was found to be suitable to describe P transformation rates from amended soils. The constant b in the power model of P for amended soils was defined as transformation rate were in the order (average of five soils) vegetables waste > sheep manure > potato > poultry manure > sunflower > rape > weeds residues. There were significant correlations between C/P in residues and parameters a and parameter b. There were significant correlations between clay content and calcium carbonate and transformation rate of P in soils. The model parameters of P are suitable to estimate the P-fertilizer effect of organic residues.     

Availability of Organic and Inorganic Phosphorus Fractions to Wheat in Toposequences of Calcareous Soils

Abstract

Information on the availability of different soil phosphorus (P) forms is useful for crop production. Phosphorus contents of 12 Iranian calcareous soils from upper‐, mid‐, and lower‐slope positions of two arid and two semiarid toposequences were fractionated to various organic and inorganic pools, and correlations of the P fractions with wheat responses were investigated. Among the inorganic P (IP) fractions, apatite type (Ca₁₀‐P) and dicalcium phosphate equivalents (Ca₂‐P) possessed the highest and the lowest amounts of P reserve in the soils, respectively. On average, about 20% of the total P was found in organic form (OP), of which 32% was labile (LOP), 51% was moderately labile (MLOP), and 17% was nonlabile (NLOP). The amounts of the soil P fractions were considerably influenced by the positions of the soils on the landscapes. The maximum contents of soil IP, Ca₂‐P, Fe‐P (iron‐bound P), and Ca₁₀‐P were observed in the lower‐slope positions. The amount of soil available [0.5 M sodium bicarbonate (NaHCO₃) extractable] P was significantly correlated with Ca₂P (r=0.895), Fe‐P (r=0.760), and Occl‐P (iron‐occluded P) (r=0.897). Direct correlation studies, however, showed that wheat shoot dry‐matter yield (DMY) was significantly affected by the amounts of Ca₂‐P, Fe‐P, OP, LOP, and MLOP fractions both at early (4 weeks) and late (10 weeks) stages of growth. All organic and inorganic P fractions, except Al‐P (aluminum‐bound P), Ca₈‐P (octacalcium phosphate equivalents), and NLOP, also showed significant relations to the amount and/or concentration of P in wheat tissues at 4 and 10 weeks after sowing. Among the measured soil properties, the amount of organic carbon was the most affecting factor on the size of the P fractions.     

Phosphorus Availability in Low-P and Acidic Soils as Affected by Liming and P Addition

Acidic soils typically suffer from high phosphorus (P) retention, a problem that can be dealt with using greater P fertilization, soil liming, or both. The aim of this work was to examine which of these practices bears the more beneficial result for Lolium perenne L. growth. In a pot experiment, five acidic soils were treated as follows: L0P0 (unamended control), L1P0 (liming only), L0P1 (P addition only), and L1P1 (both liming and P addition). We found that P amendment alone was sufficient to increase plant P levels when the initial soil P concentrations were low. Liming without P addition increased plant P satisfactorily only in the high-P soil. We conclude that P addition alone is a better practice than liming alone for improved plant growth conditions in acidic, low-P soils, unless there is relatively high P content in soil, in which case liming alone may be sufficient to increase P availability.     

不同形态氮肥对磷肥生物有效性的影响

利用盆栽试验研究了潮土中不同形态氮肥对磷肥生物有效性的影响。结果表明:不同形态氮肥处理均有抑制油菜生长初期磷素累积的作用,氯化铵处理抑制作用最突出,其次是尿素,再次是硫酸铵、硝酸铵和硝酸钙处理;油菜生长后期不同形态氮肥处理均逐渐显著促进油菜的磷累积,但氯化铵处理的促进作用仍然低于其它氮肥处理,这与不同形态氮肥处理对油菜生长的影响较一致。土壤有效磷含量受不同形态氮肥处理影响较小,而水溶性磷含量因施用不同形态氮肥均表现显著地下降,氯化铵和硫酸铵处理使土壤水溶性磷下降较多,硝酸铵、硝酸钙和尿素处理使土壤水溶性磷下降较少。     

氨基酸对三种石灰性土壤磷素有效性的影响及其作用差异机制

磷是农作物生长发育的必需元素,为了保证我国粮食安全,提高农作物的产量,提高磷肥有效性十分重要。本试验选取三种石灰性土壤（郑州潮土、周口褐土和昌图风沙土）为研究对象,通过90天的室内埋土试验,在三种土壤中研究氨基酸与磷酸一铵配施对提高土壤中磷肥有效性的影响。研究结果表明:（1）氨基酸在三种石灰性土壤中均能够提高磷酸一铵的有效性,郑州潮土、周口褐土和昌图风沙土的磷肥有效性与单施磷酸一铵相比分别提高了21.16%、10.87%和4.06%;（2）氨基酸的加入降低了土壤中Ca₂-P向Ca₈-P或其他难溶形态磷的转化,通过对三种土壤进行相关性和通径分析的得出在郑州潮土、周口褐土和昌图风沙土中主要决策因子是Ca₂-P,决策系数分别到达了0.836、0.946和0.712（P < 0.05）,郑州潮土、周口褐土主要限制因子是Ca₈-P,决策系数分别为?0.066、?0.401（P < 0.05）,昌图风沙土主要限制因子是Ca₈-P和Fe-P,决策系数分别为?0.080和?0.105（P < 0.05）;（3）氨基酸的加入能够降低三种石灰性土壤的pH和CaCO₃含量,有利于提高磷肥有效性;（4）通过对三种土壤的有效磷含量与土壤理化性质进行冗余分析,得出有机质（SOM）和碳酸钙 （CaCO₃）是影响磷肥在三种土壤中固定速率差异的主要原因,SOM和CaCO₃分别解释了有效磷含量全部变异的36.5%和25.6% （P < 0.05）。氨基酸在三种石灰性土壤中均能够提高磷肥有效性,主要途径是降低土壤的pH和CaCO₃含量,抑制Ca₂-P的快速转化。在三种石灰性土壤中,氨基酸作用有差异的主要原因是三种土壤中SOM和CaCO₃含量的差异,提高SOM,降低土壤中CaCO₃能够降低土壤对磷的固定,提高磷肥有效性。     

水稻土中铁还原与无机磷有效性的关系

采集我国吉林省吉林市(1号)、四川省邛崃市(2号)、江西省安福县(3号)及广东省雷州半岛(4号)等地区的四种典型水稻土,通过模拟厌氧培养试验,研究在厌氧还原条件下不同水稻土中Fe(II)产生量、有效性磷浓度及A l-P、Fe-P和O-P等无机磷形态变化情况。结果表明,淹水后四种水稻土中Fe(II)含量均有不同程度的增加,土壤有效磷浓度也呈现相同的变化趋势。淹水60天后在1、2、3、4号土壤中,Fe(II)的净增加量分别为5.5mg g-1,4.3mg g-1,2.1mg g-1和3.7mg g-1;有效磷的增加量分别为50 mg kg-1,18.6 mg kg-1,23 mg kg-1和12.4 mg kg-1。厌氧培养30天内土壤Fe(II)产生量与有效磷浓度的变化呈极显著的相关关系。在1、2、3、4号土壤中,Fe(II)与有效磷的相关系数依次为0.9679、0.9744、0.8949和0.7501。     

设施高肥力蔬菜地氮素调控下磷素特征研究

设施蔬菜种植中存在不合理施肥现象,土壤养分严重失调。为了解设施蔬菜地高氮肥力水平下不同氮素水平对磷素的养分吸收影响,2004—2007年在山东寿光进行不同氮素水平调控和秸秆还田试验,并于2007年冬春季进行裂区淋滤试验。结果表明,不同水平的氮素调控影响磷素含量变化,空白(NN)、有机肥(MN)、有机肥+秸秆(MN+S)供氮水平下土壤全磷含量逐年下降,降幅NNMNMN+S,全磷增幅传统氮素(CN)传统氮素+秸秆(CN+S)氮素优化+秸秆(SN+S)氮素优化(SN)。CN、CN+S供氮水平下土壤速效磷含量达到213.7、225.4 mg·kg-1,增长了17.1%、23.5%,磷素累积明显;其他供氮水平下速效磷含量逐年下降,降幅NNMNMN+SSN+SSNCNCN+S,减少氮素供应有利于减缓磷素累积,促进磷的吸收利用。除NN供氮水平下土壤有机磷含量下降外,其他处理均不同程度增加,CN、CN+S供氮水平下土壤有机磷含量累积明显(308.4、331.4 mg·kg-1),分别增长了28.5%、38.2%。SN+S供氮水平下磷的吸收系数(P2O5,mg·100 g-1)达到了1 571,增长了143.6%;CN、CN+S供氮水平下磷的吸收系数出现了负增长,CN供氮水平下达到了416(P2O5,mg·100 g-1),下降了35.5%。添加小麦秸秆极大地提高了磷的吸收能力,在一定程度上能减缓土壤速效磷的累积。淋溶液中全磷含量SNSN+S,有机磷含量SNSN+S,秸秆还田对阻控有机磷素淋溶有一定的作用,但整个冬春生长季渗滤液中全磷含量在2.6~12.0 mg·L-1,有机磷含量在0.42~4.1 mg·L-1,淋出液水质仍超过了国家安全水质标准。因此,在高肥力水平下进行氮素调控,优化氮素供应量,促进了磷素的吸收利用,对农民在高肥力水平下施肥具有指导意义。建议农民在以后的种植中减少氮肥供应量及添加高碳源秸秆进行还田,以提高肥料的利用率,减少氮磷对土壤及水体的污染。     

Nitrogen,Phosphorus, and Potassium Availability in Manure- and Sewage Sludge–Applied Soil

A field experiment with wheat (Triticum aestivum L.) was established over two growing seasons where farmyard manure and sewage sludge, along with conventional fertilizer, were added to soil. We found that ammonium N was at greater concentrations in the organic amendments treatments, indicating more beneficial dynamics (i.e., it can be taken up by plants for a greater amount of time) and thus a longer lasting effect as a nutrient for the test crop. We found that nitrogen (N), phosphorus (P), and potassium (K) uptake increased with added organic amendments. This means that when organic matter along with nutrients are added to soil, productivity may increase beyond preset targets because soil conditions greatly improve, not only chemically but also physically. Nitrates left over at the end of the growing season (residual N) were greater in the high sewage sludge and manure treatments, but not proportionally.