Evaluation of microbial methods as potential indicators of soil quality in historical agricultural fields

In agricultural ecosystems that have had consistent cropping histories, standard microbial methods may be used to evaluate past and present practices. Our objective was to evaluate several microbial methods that best indicate cropping histories and soil quality on long-term plots. We selected soil microbial carbon (C), phospholipid analyses, direct counts of total fungal and bacterial biomass, and soil enzymes (phosphatases) to measure direct and indirect microbial activity on the Sanborn Field and Tucker Prairie. The Sanborn Field has been under various cropping and management practices since 1888 and the Tucker Prairie is an uncultivated site. Seven different plots were chosen on the Sanborn Field and random samples were taken in the summit area on the Tucker Prairie, which represented a reference site. Soil microbial biomass C, phospholipids, and enzyme activity were reflective of the cropping and management histories observed on the Sanborn Field. Enzymatic activity was highly correlated to soil organic matter. The direct counts of fungal and bacterial biomass showed that fungal populations dominated these soils, which may be attributed to soil pH. Soil microbial biomass C and enzyme assays seemed to be better potential indicators of cropping histories than the other methods tested in the long-term plots.This paper has been assigned by the Missouri Agricultural Experiment Station to Journal Series no. 12043     

Effect of Integrated Nutrient Management on Soil Physical Properties and Crop Productivity under a Maize (Zea mays)–Mustard (Brassica campestris) Cropping Sequence in Acidic Soils of Northeast India

A five-year (2001/02–2006/07) field experiment was carried out on acidic clay loam soil classified as Typic Hapludalf with a maize–mustard crop sequence to study the effect of continuous application of nitrogen, phosphorus, and potassium (NPK) fertilizers alone and in combination with lime, farmyard manure (FYM), and biofertilizers on soil physical properties, soil organic carbon (SOC), soil microbial biomass carbon (SMBC), and crop yields on the hilly ecosystem of Meghalaya. Significant improvement in the soil physical conditions of the soil was observed under integrated application of organic manure and inorganic fertilizers. Addition of NPK fertilizers along with organic manure, lime, and biofertilizers increased soil organic carbon (SOC) content, aggregate stability, moisture-retention capacity, and infiltration rate of the soil while reducing bulk density. The SOC content under the treatment of 100% NPK + lime + biofertilizer + FYM was significantly greater (68.58%) than in control plots. Maize and mustard crop yields also significantly increased (4.73- and 21.09-folds, respectively) with continuous application of balanced inorganic (100% NPK) + lime + biofertilizer + FYM as compared to the control plots. However, crop yields drastically reduced under application of integrated nutrients without FYM as compared to the treatment with FYM application. Thus, the results suggest that integrated use of a balanced inorganic fertilizer in combination with lime and organic manure sustains a soil physical environment that is better for achieving higher crop productivity under intensive cropping systems in the hilly ecosystem of northeastern India.     

Influence of inorganic fertilizers and organic amendments on soil organic matter and soil microbial properties under tropical conditions

 Soil organic matter level, mineralizable C and N, microbial biomass C and dehydrogenase, urease and alkaline phosphatase activities were studied in soils from a field experiment under a pearl millet-wheat cropping sequence receiving inorganic fertilizers and a combination of inorganic fertilizers and organic amendments for the last 11 years. The amounts of soil organic matter and mineralizable C and N increased with the application of inorganic fertilizers. However, there were greater increases of these parameters when farmyard manure, wheat straw or Sesbania bispinosa green manure was applied along with inorganic fertilizers. Microbial biomass C increased from 147 mg kg^–1 soil in unfertilized soil to 423 mg kg^–1 soil in soil amended with wheat straw and inorganic fertilizers. The urease and alkaline phosphatase activities of soils increased significantly with a combination of inorganic fertilizers and organic amendments. The results indicate that soil organic matter level and soil microbial activities, vital for the nutrient turnover and long-term productivity of the soil, are enhanced by use of organic amendments along with inorganic fertilizers. Received: 6 May 1998     

Soil organic C in the tallgrass prairie-derived region of the corn belt: effects of long-term crop management

Concerns with rising atmospheric levels of CO₂ have stimulated interest in C flow in terrestrial ecosystems and the potential for increased soil C sequestration. Our objectives were to assess land management effects on soil organic carbon (SOC) dynamics and SOC sequestration for long-term studies in the tallgrass prairie region of the US. Major losses of SOC following conversion of native prairie to arable agriculture at Sanborn Field and the Morrow Plots were rapid (20 to 40 yr), occurred in response to greatly reduced C inputs and accelerated C decay rates, and had largely abated by the mid-1900s. Losses of SOC occurred mainly in easily decomposable, labile C fractions. At Sanborn Field, modeled labile SOC was reduced to 4% of native prairie levels for treatments with low C inputs. A large capacity for soil C sequestration likely exists in the tallgrass prairie region, if labile C pools can be replenished. This agroecosystem has a strong C decomposition regime and increased sequestration of labile C will rely on management practices that increase C inputs (i.e., fertilization, returning crop residues) and stabilize labile C (i.e., perennial cropping, reduced tillage). The capacity for soil C sequestration, however, will vary considerably among sites and be dependent on initial levels of labile SOC and the ability of management practices to stabilize greater inputs of labile C.     

Loss of phosphorus from soil in semi-arid northern Tanzania as a result of cropping: evidence from sequential extraction and 31P-NMR spectroscopy

In semi‐arid northern Tanzania, the native woodland is being rapidly cleared and replaced by low input agriculture. This has resulted in pronounced environmental degradation, and in particular loss of phosphorus (P) from the soil. We have used sequential extraction and ³¹P‐NMR to investigate the effects of land use changes, i.e. native woodland, degraded woodland, cultivation for 3 and 15 years and homestead fields where manure was applied, on the amount and structural composition of P in this soil. Clearing and continuous cultivation reduced both organic and inorganic P in the soil. The difference in the amount of organic P from the bulk soil of the fields cultivated for 3 and 15 years was not statistically significant (P < 0.05), suggesting that most of the depletion in organic P occurred during the first 3 years of cultivation. By contrast, in the homesteads, there was much organic and inorganic P in the soil. The ³¹P‐NMR revealed that cultivation resulted in a 53% depletion of orthophosphate diester P, whereas only a 30% and 39% reduction of orthophosphate monoester P was found in the bulk soil after 3 and 15 years of cultivation, respectively. These results concur with the suggestion that diester P constitutes more easily mineralizable forms of organic P in soil than does monoester P. Our ³¹P‐NMR also showed that 70% of the inorganic orthophosphate P was depleted from the coarse and fine sand separates as a result of cultivation. The influence of clearing and subsequent cropping on the amount and forms of P was more pronounced in the coarse and fine sand than in the silt and clay, stressing the importance of particle size and chemical properties such as organic matter and oxides in the availability of P in this soil. Our results show that the current low input agricultural practice is not sustainable, and that practices must be developed to combat the ongoing degradation of the soil. A combined use of available organic materials such as animal manure with the judicious use of inorganic fertilizers can replenish the soil's fertility.     

Effects of Continuous Use of Chemical Fertilizers and Manure on Soil Fertility and Productivity of Maize–Wheat under Rainfed Conditions of the Western Himalayas

Long-term effects of continuous use of chemical fertilizers and manure on soil fertility and productivity of a maize–wheat system were investigated in the ongoing long-term fertilizer experiment, during rabi (2007–2008) and kharif (2008) seasons at the research farm of Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University–Hill Agricultural Research and Extension Centre, Dhaulakuan. After 16 cropping cycles, bulk density decreased in plots where farmyard manure (FYM) was applied, whereas pH decreased in all the treatments. The organic carbon content of the soil increased in all the treatments except 100% nitrogen (N). Cation exchange capacity (CEC) increased in all the treatments over the initial status of the soil. Available N showed buildup over the initial status in most of the treatments. Available phosphorus (P) declined from initial status in treatments where only N was applied alone or with FYM. There was reduction in available potassium (K) status in all the treatments except 100% NPK. Continuous addition of FYM with balanced application of inorganic fertilizers improved content of exchangeable calcium (Ca) and magnesium (Mg) over initial status compared to imbalanced application of fertilizers. Continuous use of imbalanced inorganic fertilizers resulted in lesser crop yields and nutrient uptake compared to that with the application of balanced dose of inorganic fertilizers with FYM.     

塑料大棚内长期施肥对菜田土壤磷素组成及其含量影响

对塑料大棚内自1988年开始的蔬菜施肥长期定位试验田土壤磷索组分和含量进行了研究.结果表明,除了长期单独施用氮肥引起耕层土壤全P、有效P降低外.其他施肥处理均能提高土壤中全P和有效P含量.长期施用有机肥土壤闭蓄态P(O-P)含量最高.占无机P总置的35%～47%;不施有机肥土壤磷酸钙(Ca-P)含量最高,占无机P总量的29%～39%.施用有机肥可以显著提高土壤有机P总量,有机肥组各处理土壤活性有机P和中等活性有机P含量均显著高于不施有机肥组各对应处理,而稳定性有机P和高稳定性有机P含量则低于不施有机肥组.长期施用磷肥会增加土壤中无机P积累,且有效性较高的Ca-P、磷酸铝(Al-P)积累程度高于较稳定的O-P、磷酸铁(Fe-P),土壤有效P含量与各组分无机P及其总量、活性有机P、中等活性有机P及有机P总量呈显著正相关.而与稳定性有机P、高稳定性有机P和全P含量的相关性不明显.因此,长期施用有机肥和磷肥能够改变土壤磷索组成.提高磷素有效性.     

Effect of management practices and cropping systems on earthworm abundance and microbial activity in Sanborn Field: a 115-year-old agricultural field

Sanborn Field, an agricultural demonstration field at the University of Missouri-Columbia, has over 100 years of cropping histories and management practices implemented at this site. We examined the effect of these cropping systems and management practices on earthworm populations and microbial activity. A field experiment was conducted to characterize and quantify earthworms and to determine the microbial activity in the same selected plots. We sampled 14 plots at the site, six of which were the original plots established in 1888 with the same cropping histories and management, and eight of which had been modified over the years to accommodate changing farmer needs and scientific questions. Earthworms and soil samples were collected in the spring and fall of 1999. Aporrectodea trapezoides, Aporrectodea caliginosa, and Lumbricus terrestris were the dominant species found in this field. Lumbricus terrestris was commonly associated with the no-tillage plot at Sanborn Field. Due partly to soil moisture conditions, most of the species were found and identified during the spring. Microbial activity, as expected, was greatest during the spring. Manure, no-tillage and crop rotations that include legumes had the greatest earthworm abundance and microbial activity. In general, where no fertility treatments were added to soil or where food sources were lacking, earthworm abundance decreased significantly. The abundance of earthworms found in this field reflected the cropping history and management practices used recently and within the last 100 years. In most cases, microbial activity showed similar trends as earthworm density. However, some dynamic microbial transformations, like nitrification, do not always follow the same trend as potential soil quality biotic indicators. Earthworms, along with microbial activity, may serve as useful soil quality indicators in sustained and short-term field trials.     

Changes in an Alfisol under long-term application of manure and inorganic fertilizer

Abstract. Changes in surface soil properties of a savanna Alfisol under cultivation with applications of manure and inorganic NPK fertilizer were evaluated after 45 years of annual cropping. Soils from treatments with fertilizer only, fertilizer in combination with farmyard manure (FYM) at both high and low rates were compared to soil from a control receiving neither fertilizer nor manure. The high rate of FYM and fertilizer significantly improved soil aggregation, increased C, N and P status, while reducing soil penetration resistance. The results showed that there is a need to use both manure and inorganic fertilizer to maintain soil fertility in savanna soils under continuous cultivation.     

小麦-玉米-大豆轮作下黑土农田土壤呼吸与碳平衡

农田生态系统是陆地生态系统的重要组成部分,探讨农田生态系统的土壤呼吸与碳平衡对于科学评价陆地生态系统在全球变化下的源汇效应具有重要意义。基于中国科学院海伦农业生态实验站的长期定位试验,对不同施肥处理下黑土小麦-玉米-大豆轮作体系2005—2007年的作物固碳量与土壤CO2排放通量进行了观测,并对该轮作体系下黑土农田生态系统的碳平衡状况进行了估算。结果表明:在小麦-玉米-大豆轮作体系中,作物固碳量的高低表现为:玉米>大豆>小麦,平均值分别为6 513 kg(C).hm-2、4 025 kg(C).hm-2和3 655kg(C).hm-2。从作物生长季土壤CO2排放总量来看,3种作物以大豆农田生态系统的土壤CO2排放总量最高,平均值达4 062 kg(C).hm-2;其次为玉米,为3 813 kg(C).hm-2;而小麦最低,为2 326 kg(C).hm-2。3种作物轮作下NEP(净生态系统生产力)均为正值,表明黑土农田土壤-作物系统为大气CO2的"汇",不同作物系统的碳汇强度表现为玉米>小麦>大豆,三者的平均值分别为3 215 kg(C).hm-2、1 643 kg(C).hm-2和512 kg(C).hm-2。长期均衡施用氮、磷、钾化肥或氮、磷、钾化肥配施有机肥后,小麦、玉米和大豆农田生态系统的固碳量和土壤CO2排放总量均明显增加,并在氮、磷、钾配施有机肥处理下达到最高。不同的施肥管理措施将改变土壤-植物系统作为大气CO2"汇"的程度,总体表现为化肥均衡施用下NEP值较高,而化肥与有机肥配施下农田生态系统的NEP值较低。     

Biological and chemical properties of arable soils affected by long-term organic and inorganic fertilizer applications

 Using soils from field plots in four different arable crop experiments that have received combinations of manure, lime and inorganic N, P and K for up to 20 years, the effects of these fertilizers on soil chemical properties and estimates of soil microbial community size and activity were studied. The soil pH was increased or unaffected by the addition of organic manure plus inorganic fertilizers applied in conjunction with lime, but decreased in the absence of liming. The soil C and N contents were greater for all fertilized treatments compared to the control, yet in all cases the soil samples from fertilized plots had smaller C:N ratios than soil from the unfertilized plots. The soil concentrations of all the other inorganic nutrients measured were greater following fertilizer applications compared with the unfertilized plots, and this effect was most marked for P and K in soils from plots that had received the largest amounts of these nutrients as fertilizers. Both biomass C determined by chloroform fumigation and glucose-induced respiration tended to increase as a result of manure and inorganic fertilizer applications, although soils which received the largest additions of inorganic fertilizers in the absence of lime contained less biomass C than those to which lime had been added. Dehydrogenase activity was lower in soils that had received the largest amounts of fertilizers, and was further decreased in the absence of lime. This suggests that dehydrogenase activity was highly sensitive to the inhibitory effects associated with large fertilizer additions. Potential denitrification and anaerobic respiration determined in one soil were increased by fertilizer application but, as with both the microbial biomass and dehydrogenase activity, there were significant reductions in both N₂O and CO₂ production in soils which received the largest additions of inorganic fertilizers in the absence of lime. In contrast, the size of the denitrifying component of the soil microbial community, as indicated by denitrifying enzyme activity, was unaffected by the absence of lime at the largest rate of inorganic fertilizer applications. The results indicated differences in the composition or function of microbial communities in the soils in response to long-term organic and inorganic fertilization, especially when the soils were not limited. Received: 10 March 1998     

有机肥施用模式对蔬菜产量、土壤化学性质及微生物的影响

在广州市蔬菜集约化种植区连续进行了6茬菜心试验,探讨有机肥施用模式[施无机肥(CK)、无机肥配施国产生物有机肥(BM)、无机肥配施腐殖酸(HA)、无机肥配合淋施复合芽孢杆菌剂(BSP)、无机肥配施腐殖酸并淋施复合芽孢杆菌剂(HA+BSP)、无机肥配施水沤腐熟鸡粪并淋施复合芽孢杆菌剂(CM+BSP)、无机肥配施复合芽孢杆菌剂堆沤腐熟鸡粪(BSPCM)]对蔬菜产量、土壤化学性质及微生物的影响。结果表明,不同茬别菜心产量差别较大。连续6茬试验中,CM+BSP处理菜心产量均为最高且显著高于CK处理,BSPCM处理菜心产量仅次于CM+BSP处理。BM、CM+BSP、BSPCM处理能提高土壤pH,降低连作土壤的酸化风险。随着种植茬数的增加,CM+BSP处理土壤细菌、真菌和微生物总数持续增加,显著高于原始土壤和其他施肥处理,BSPCM处理次之。CK处理土壤中细菌、真菌及微生物总量均比原始土壤下降。在连作菜地蔬菜生产中,在施用无机肥基础上配施适量水沤腐熟鸡粪,并在蔬菜生长过程中淋施复合芽孢杆菌剂,不但可提高蔬菜产量,而且具有培肥、活化和改良土壤生物质量的作用,有利于减轻蔬菜连作障碍,实现集约化蔬菜种植的可持续发展。     

长期有机无机肥配施下红壤性稻田水稻产量及土壤有机碳变化特征

利用中国农业科学院红壤实验站红壤稻田长期定位试验,研究了长期有机无机肥配施下双季稻增产潜力和土壤有机碳变化特征。31年的试验结果表明,1）施肥能促进水稻早晚稻稻谷和地上部产量增加,其中,有机肥配施均衡的NPK处理促进作用最大,NPKM处理下稻谷年均产量比NPM、 NKM、 PKM、 M和NPK分别高 5.8%、 10.9%、 16.2%、 15.9%和20.4%。2）施肥能促进水稻土有机碳含量增加,其中,有机肥配施均衡的NPK处理提升效果最为明显, NPKM处理下所测年度土壤有机碳平均含量比NPM、 NKM、 PKM、 M和NPK分别高出2.5%、 3.5%、 2.0%、 0.6%和 32.8%。3）随着试验的进行,单施有机肥对早、 晚稻稻谷和地上部产量的促进效果逐步优于单施化肥氮、 磷、 钾处理（NPK）,对土壤有机碳的提升效果也明显优于单施化肥氮、 磷、 钾。红壤性稻田双季稻生产实践中,有机无机肥配施模式值得推荐,但需均衡配施化肥氮、 磷、 钾。     

Effects of Organic Amendments on Soil Physical Attributes and Aggregate-Associated Phosphorus Under Long-Term Rice-Wheat Cropping

The quantification of phosphorus(P) in bulk soil and P distribution in different size fractions of water-stable aggregates(WSAs)are important for assessing potential P loss through runoff. We evaluated available and total P distribution within WSAs of a sitty clay to clay soil in a long-term fertility experiment of a rice-wheat cropping system in India. Surface soil samples were collected from seven plots amended with NPK fertilizers in combination with or without organic amendments, farmyard manure(FYM), green manure(GM), and paddy straw(PS). The plot with no NPK fertilizers or organic amendments was set as a control. The soil samples were separated by wet sieving into four soil aggregate size fractions: large macroaggregates( 2.0 mm), small macroaggregates(0.25–2.0 mm), fine microaggregates(0.05–0.25 mm), and a silt + clay-sized fraction( 0.05 mm). Structural indices were higher in the soil receiving organic amendments than in the soil receiving inorganic fertilizer alone. Organically amended soil had a higher proportion of stable macroaggregates than the control and the soil receiving inorganic fertilizer alone, which were rich in microaggregates. Total and available P contents within WSAs were inversely related to the aggregate size, irrespective of treatment. The distribution of available and total P in the soil aggregate size fraction was as follows: silt + clay-size fraction small macroaggregates fine microaggregates large macroaggregates. Within a size class, aggregate-associated available and total P contents in the organically amended soil were in the following order: FYM PS ≥ GM. The available P content of the microaggregates( 0.25 mm) was 8-to 10-times higher than that of the macroaggregates( 0.25 mm), and the total P content of the microaggregates was 4-to 5-times higher than that of the macroaggregates. Cultivation without organic amendments resulted in more microaggregates that could be checked by the application of organic amendments such as FYM and GM, which increased the proportion of water-stable macroaggregates by consolidating microaggregates into macroaggregates.     

长期施肥条件下设施栽培土壤无机磷组分及其剖面分布特点

采用张守敬和Jackson(1957年)提出的土壤无机磷分组测定方法,对施肥17年的蔬菜保护地土壤无机磷的形态及其剖面分布规律进行了研究。结果表明,土壤无机磷组分及其剖面分布受施入的有机肥影响较大。施有机肥组(A组),土壤中O-P含量占无机磷总量百分数最高,平均为35%～47%;不施有机肥组(B组),土壤中Ca-P含量占无机磷总量百分数最高,平均为29%～39%。长期施用有机肥能够增加20cm以下土层中无机磷含量;施有机肥组(A)和不施有机肥组(B)各处理土壤不同形态无机磷含量均随土层加深而逐渐降低,但在0～60cm土层内,有机肥组不同形态无机磷含量均高于不施有机肥组。长期施用磷肥会增加土壤中无机磷的积累量,而且有效性较高的Ca-P、Al-P积累程度高于较稳定的O-P、Fe-P积累程度。     

Soil Organic Carbon,Total Nitrogen,and Soil pH,in a Long-Term Continuous Winter Wheat (Triticum Aestivum L.) Experiment

Continuous use of organic and inorganic fertilizers influences soil physical and chemical properties. Stored samples from the last 24 years of the Magruder Plots were analyzed to document changes in soil organic carbon (SOC), total nitrogen (TN) and soil pH. Since 1947, the same six treatments have been evaluated. Treatments included the use of cattle manure, inorganic nitrogen (N), phosphorus (P), potassium (K), and lime (L). Each year, a composite surface soil sample (0–15 cm) was taken in each plot, air-dried at ambient temperature, ground to pass a 2 mm sieve, and stored at room temperature, 25°C. Averaged over 24 years’ the manure plots resulted in the highest SOC and TN. Manure application maintained SOC at 0.92 and adequate soil pH (>6.0). The use of commercial fertilizers lowered soil pH over time but had higher yields compared to the manure plot.     

Effects of Long-Term Inorganic and Organic Fertilization on Soil Micronutrient Status

Soil micronutrients were studied on loess soil with an 18-year long-term experiment. The results indicated that total soil iron and copper contents were similar under all treatments, but total soil manganese and zinc contents were significantly greater at the surface soil in the fertilized plots than in the controls, and total manganese contents were significantly greater in the whole soil profile under manure plus inorganic fertilizers than under controls. Generally, application of inorganic fertilizers had no effects on available soil micronutrient contents. The straw plus inorganic fertilizers significantly increased available manganese content at surface soil and available iron in subsurface soils. However, manure plus inorganic fertilizers significantly augmented soil-available iron contents throughout the profile, and raised available manganese, copper, and zinc contents, respectively, at surface soil relative to controls. The results suggest that long-term input of organic amendments alter the properties of soil and increase its plant-available micronutrient contents.     

Effects of cover crops,compost, and manure amendments on soil microbial community structure in tomato production systems

Soil microbial community structure and crop yield was investigated in field tomato production systems that compared black polyethylene mulch to hairy vetch mulch and inorganic N to organic N. The following hypotheses were tested: (1) hairy vetch cover cropping increases crop yield and significantly affects soil microbial community structure when compared to the standard plastic mulch and synthetic fertilizer-based system; (2) within plastic mulch systems, organic amendments will increase crop yield and significantly affect soil microbial community structure when compared to synthetic fertilizer; (3) crop yields and microbial community structure will be similar in the hairy vetch cover cropping and the organic amended plasticulture systems. Treatments consisted of ammonium nitrate (control), hairy vetch cover crop, hairy vetch cover crop and poultry manure compost (10 Mg/ha), three levels of poultry manure compost (5, 10, and 20 Mg/ha), and two levels of poultry manure (2.5 and 5 Mg/ha). Black polyethylene mulch was used in all treatments without hairy vetch. Fatty acid analysis was used to characterize the total soil microbial community structure, while two substrate utilization assays were used to investigate the community structure of culturable bacteria and fungi. Crop yield was not significantly increased by hairy vetch cover cropping when compared to black polyethylene mulch, although microbial community structure was significantly affected by cover cropping. Under black polyethylene mulch, crop yields were significantly increased by the highest levels of compost and manure when compared to inorganic fertilizer, but there was no detectable effect on soil microbial community structure. When cover cropping was compared to organic amended plasticulture systems, crop yields were similar one year but dissimilar the next. However, hairy vetch cover cropping and organic amendments under black plastic mulch produced significantly different soil microbial community structure.     

Changes in Soil Iron Fractions and Availability in the Loess Belt of Northern China After 28 Years of Continuous Cultivation and Fertilization

Iron(Fe) deficiency in calcareous soils of the Loess Plateau of China is a wide spread issue and primarily affects agricultural production due to the relatively higher soil pH and carbonate content. Understanding the relationships between Fe distribution in soil fractions, Fe availability, and their responses to cropping and fertilization could provide essential information for assessing Fe availability in soils and managing soils to improve Fe availability. A long-term field experiment was established in 1984 in a split-plot design using cropping systems as main plots and fertilizer treatments as subplots on a farmland in the Loess Plateau. The cropping systems included fallow, continuous wheat cropping, continuous alfalfa cropping, continuous maize cropping, and a rotation system that included a legume. Various fertilization treatments using chemical and/or manure fertilizers were included in each cropping system. Soil samples were collected from 0–10 and 20–40 cm depths in 2012. Long-term planting of crops significantly increased the concentrations of available Fe in the soils. The largest increase was observed in the continuous alfalfa cropping system. Long-term cropping significantly increased the concentrations of Fe associated with carbonates and organic matter, but decreased the concentration of Fe associated with minerals in the soils. The effect of fertilization on the distribution of Fe in the soil fractions varied with cropping system and soil depth. The fertilization treatment with manure generally increased the concentrations of Fe associated with the soil fractions.Long-term cropping and fertilization in the highland farmland significantly affected the availability of Fe and the distribution of Fe fractions in the soil.