Surface Soil Nitrogen Research Articles

Improved soil surface nitrogen balance method for assessing nutrient use efficiency and potential environmental impacts within an alpine meadow dominated region

The soil surface nitrogen balance (SSNB) method is commonly used to assess the nutrient use efficiency (NUE) of agricultural systems and any associated potential environmental impacts. However, the nitrogen flow of wide natural grasslands and other natural areas differ from that of artificial croplands and mown grasslands. In this study, we integrated root growth and the important nutrient resorption process into the SSNB model and used the improved model to clarify the nitrogen (N) flow and balance in the Three Rivers Headwater Region (TRHR)—an area dominated by alpine meadows—from 2012–2019. In the grassland system, the N surplus (ΔN) was 0.274 g m−2 year−1, and root return (BLD) dominated the N input, accounting for 67% of the total input (3.924 g m−2 year−1). N resorption was the main internal N flow in the grassland system (1.079 g m−2 year−1), and 30% of grassland uptake (NUP−grass). The ΔN of the agricultural system was 1.097 g m−2 year−1, which was four times that of the grassland, and chemical fertilizer was the largest input, accounting for 84% of the total input. The NUE in grassland was 93%, which suggests a risk of soil mining and degradation, while that of cropland was 76% and within an ideal range. The ΔN provides a robust measure of river N export, the TRHR was divided into three catchments, and the export coefficient was 16.14%–55.68%. The results of this study show that the improved SSNB model can be applied to a wide range of natural grasslands that have high root biomass and resorption characteristics.

Relative importance of soil properties and functional diversity to the spatial pattern of the forest soil nitrogen

Surface soil nitrogen (SN) is the main source of plant nutrient uptake, and its dynamic change is related to forest productivity, ecosystem carbon and nitrogen cycles, and water conservation. However, few studies have investigated the factors influencing SN. The linear mixing effect and generalized additivity model were used to investigate the spatial patterns and influencing factors of SN by collecting and measuring the total nitrogen content of forest soil samples in the middle and lower reaches of the Xijiang River Basin (XRB). We found that the total nitrogen content in broad-leaved forest soils was significantly higher than that in coniferous forest soils. Forest SN was influenced by soil properties and diversity indicators, and the full model constructed by influencing factors was more applicable to broad-leaved forests. Soil properties were the main explanatory factor for SN (53.53% in the full model, 61.02% in broad-leaved forests), with sub-surface soil nitrogen (sub SN) being the largest explanatory quantity factor (48.52% in the full model, 58.04% in broad-leaved forests). Therefore, forest management in the XRB should avoid damaging the sub-surface soils to prevent nitrogen loss. In the context of global change, the further study of the effect of nitrogen deposition on SN is warranted.

Gridded soil surface nitrogen surplus on grazing and agricultural land: Impact of land use maps

Excess N application on agricultural land greatly impacts the environment in multiple ways, driven by population growth and improving quality of human diets. Therefore, it is essential to quantify the sources of the emissions of N compounds and their determinants (e.g. biological N fixation (BNF), mineral fertilizer, manure N and N deposition) to develop adequate mitigation measures. Here we aim at comprehensively mapping and quantifying N fluxes on agricultural land to analyze these sources on different scales. As underlying grazing land maps used for such calculations are fairly different in terms of methodology and definition and thus spatial extent and pattern, we investigate how this diversity in grazing land maps affects quantification of N indicators. We compared three different global grazing land maps and analyzed the propagation of differences to discrepancies in N indicators calculated from them. We discovered that (i) area differences propagated to high discrepancies in N surplus mostly in Asia, and to a minor extent also in Europe and Northern Africa. (ii) BNF constitutes an important translator for differences on grazing land to N indicators, while also being a source of further uncertainty, which warrants further scrutiny. (iii) A more inclusive definition of grazing land results in overall less N surplus given the larger areas included but allows to provide a more comprehensive estimate of the influence of human activity on the N cycle. This study is the first to provide an in-depth analysis of the effect of grazing land and agricultural land area differences on various N budget terms and N indicator calculation, highlighting opportunities for further research, and the importance of a comprehensive accounting of N surplus when using an inclusive definition of grazing land.

Quantifying On‐Farm Nitrous Oxide Emission Reductions in Food Supply Chains

AbstractReducing nitrous oxide (N2O) emissions from agriculture is critical to limiting future global warming. In response, a growing number of food retailers and manufacturers have committed to reducing N2O emissions from their vast networks of farmer suppliers by providing technical assistance and financial incentives. A key challenge for such companies is demonstrating that their efforts are leading to meaningful progress toward their climate mitigation commitments. We show that a simplified version of soil surface nitrogen (N) balance—or partial N balance—the difference between N inputs to and outputs from a farm field (fertilizer N minus crop N), is a robust indicator of direct N2O emissions from fields with maize and other major rainfed temperate‐region crops. Furthermore, we present a generalized environmental model that will allow food‐supply‐chain companies to translate aggregated and anonymized changes in average N balance across their supplying farms into aggregated changes in N2O emissions. This research is an important first step, based on currently available science, in helping companies demonstrate the impact of their sustainability efforts.

The Impact of Agricultural Production and Policy on Water Quality during the Dry Year 2018, a Case Study from Germany

The hot summer of 2018 posed many challenges with regard to water shortages and yield losses, especially for agricultural production. These agricultural impacts might further pose consequent threats for the environment. In this paper, we deduce the impact of droughts on agricultural land management and on water quality owing to nitrate pollution. Using national statistics, we calculate a Germany-wide soil surface nitrogen budget for 2018 and deduce the additional N surplus owing to the dry weather conditions. Using a model farm approach, we compare fertilization practices and legal restrictions for arable and pig breeding farms. The results show that, nationwide, at least 464 kt of nitrogen were not transferred to plant biomass in 2018, which equals an additional average nitrogen surplus of 30 kg/ha. The surplus would even have amounted to 43 kg/ha, if farmers had continued their fertilization practice from preceding years, but German farmers applied 161 kt less nitrogen in 2018 than in the year before, presumably as a result of the new implications of the Nitrates Directive, and, especially on grassland, owing to the drought. As nitrogen surplus is regarded as an “agri-drinking water indicator” (ADWI), an increase of the surplus entails water pollution with nitrates. The examples of the model farms show that fertilization regimes with high shares of organic fertilizers produce higher nitrogen surpluses. Owing to the elevated concentrations on residual nitrogen in soils, the fertilization needs of crops in spring 2019 were less pronounced than in preceding years. Thus, the quantity of the continuously produced manure in livestock farms puts additional pressure on existing storage capacities. This may particularly be the case in the hot-spot regions of animal breeding in the north-west of Germany, where manure production, biogas plants, and manure imports are accumulating. The paper concludes that water shortages under climate change not only impact agricultural production and yields, but also place further challenges and threats to nutrient management and the environment. The paper discusses preventive and emergency management options for agriculture to support farmers in extremely dry and hot conditions.

Combined ditch buried straw return technology in a ridge–furrow plastic film mulch system: Implications for crop yield and soil organic matter dynamics

A ridge–furrow plastic film mulch (RP) configuration can increase crop and straw yields in semiarid areas of China. This study advocated for a novel soil tillage practice (ditch buried straw return) in a ridge–furrow plastic film mulch system. There were three treatments: (i) flat cultivation, CK; (ii) ridge–furrow plastic film mulch with no straw return (RP−S); and (iii) ridge–furrow plastic film mulch with ditch buried straw return (RP+S). Field experiments were conducted from 2015 to 2018 on the Loess Plateau of China to study the effects of straw incorporation on maize growth, biomass, water use efficiency, soil organic carbon, and total nitrogen sequestration capacity in RP systems. The mean rate of straw decomposition in RP+S reached 81 % at harvest of each year. The RP systems provided suitable hydrothermal conditions for maize growth. Both RP treatments promoted maize growth, particularly biomass accumulation and plant height under RP+S. The RP+S treatment also had greater concentrations of soil organic carbon and total nitrogen in surface soil at harvest, higher total nitrogen accumulation, nitrogen content and crude protein in maize grain, and higher maize yields and water use efficiencies than the other two treatments. In summary, the introduction of ditch buried straw return to RP is an effective measure for promoting the sustainable development of film mulching systems in semiarid regions of China by improving soil fertility and increasing crop yields.

Inventory of apparent nitrogen and phosphorus balance and risk of potential pollution in typical sloping cropland of purple soil in China—A case study in the Three Gorges Reservoir region

Agricultural non-point source pollution of nitrogen (N) and phosphorus (P) exerts a key influence on aquatic environment safety. Purple soil and sloping cropland make up the highest proportion of all soil types and land-use pattern in the up and middle reaches of Yangtze River. Therefore, a study on nutrients balance for risk assessment in sloping cropland of purple soil will contribute to the understanding of the causes of eutrophication in aquatic environment in China. The Organization for Economic Cooperation and Development (OECD) have developed the soil surface nitrogen balance indicator to estimate potential N pollution through measuring the difference between agricultural inputs and outputs. Based on this indicator, we established a framework, a methodology, and a database for calculating the N and P balance for typical sloping cropland of purple soil in TGR region, and evaluated the impact of nutrients balance on agricultural production and environment. For the basic watershed of Xinzheng unit, which mainly consists of sloping cropland of purple soil, N and P inputs were 755 and 107kgha−1a−1, with 68.4% of N and 56.1% of P inputs originating from chemical fertilizer. The N and P outputs were 482 and 60kgha−1a−1; the N in crops and P in straw accounted for 23.5% and 45.6% of total outputs, respectively. The N and P surplus intensities were 273 and 47kgha−1a−1, much higher than the respective risk thresholds of 180kgha−1a−1 and 35kgha−1a−1, indicating a risk of N and P potential pollution in aquatic environments via cropland discharge. It is essential to utilize proper fertilization methods and improve fertilizer use efficiency in sloping cropland of purple soil in China.

Effects of community structure on precipitation‐use efficiency of grasslands in northern Tibet

AbstractQuestions(1) What are the primary factors determining the precipitation‐use efficiency (PUE) in northern Tibet; (2) how does PUE respond to the gradients of biotic and abiotic factors; and (3) how do the composition and structure of plant functional groups (PFGs) affect PUE?LocationNorthern Tibet, China.MethodsA community survey of species composition, cover and above‐ground net primary productivity (ANPP) was conducted within 1 m × 1 m plots in 62 slightly disturbed sites. The effects of community features (total cover, cover of PFGs and species richness) and environmental factors [mean annual precipitation (MAP), mean annual temperature, surface soil bulk density, pH and C and N content] on PUE were identified through Pearson's correlation analyses, hierarchical partitioning and ordinary regressions.ResultsAlong the precipitation gradient, ANPP and PUE increased exponentially. Among the community features, total cover and cover of PFGs, including forbs and sedges, were the primary factors that determined PUE. The three cover variables, together with species richness, positively affected PUE and accounted for 47.6% of the total variation in PUE. Among the environmental factors, MAP, surface soil pH and N content were the most significantly related to PUE and accounted for 29.9% of the total contribution.ConclusionCommunities with high cover, species richness and nutrient content, but low soil bulk density, presented the highest PUE. At a regional scale, PUE depended mainly on plant cover, especially the cover of PFGs, namely, forbs and sedges. Environmental factors, including MAP and surface soil N and C content, positively affected PUE, whereas soil pH and bulk density negatively affected PUE. Our results highlight the importance of considering community structure to understand PUE variations in natural alpine grasslands.

Annual agricultural N surplus in France over a 70-year period

High levels of nitrogen (N) contamination of ground and surface water are still detected at European and national scales, despite the implementation of Directives, highlighting the need to improve understanding of changes in N pressure. Soil surface nitrogen balance was investigated at the county level in France over a 70-year period to identify areas with high N surpluses and trends in N pressure. Soil surface nitrogen balances were calculated for 90 NUTS3 (Nomenclature of Territorial Units for Statistics in the EU) called ‘departments’ (ranging from 611 to 10,145 km2, median surface area 6032 km2) and one NUTS2 entity. Over the whole period, the N surplus calculated for France as a whole averaged 37 kgN per ha of utilized agricultural area (UAA) and departmental N surpluses mean ranged from 10 to 86 kgN ha UAA−1. Imprecision, i.e. an 80% confidence interval in N surpluses, was calculated using Monte Carlo simulation. Average imprecision for the whole period ranged from 6 to 45 kgN ha UAA−1 across different departments. Analysis revealed that yearly and departmental imprecision values were mainly correlated with N export (R2 = 0.46). Despite this imprecision, the soil surface nitrogen balance was found to be a consistent and suitable tool to determine trends in N pressure at the department level. The model revealed an upward trend in N surplus until the 1990s for 82% of the area studied, and a downward or stable trend for more than 90% of the area since the European Nitrates Directive has been implemented.

Managing cattle grazing intensity: effects on soil organic matter and soil nitrogen

Extensive cattle grazing is the dominant land use in northern Australia. It has been suggested that grazing intensity and rainfall have profound effects on the dynamics of soil nutrients in northern Australia’s semi-arid rangelands. Previous studies have found positive, neutral and negative effects of grazing pressure on soil nutrients. These inconsistencies could be due to short-term experiments that do not capture the slow dynamics of some soil nutrients and the effects of interannual variability in rainfall. In a long-term cattle grazing trial in northern Australia on Brown Sodosol–Yellow Kandosol complex, we analysed soil organic matter and mineral nitrogen in surface soils (0–10 cm depth) 11, 12 and 16 years after trial establishment on experimental plots representing moderate stocking (stocked at the long-term carrying capacity for the region) and heavy stocking (stocked at twice the long-term carrying capacity). Higher soil organic matter was found under heavy stocking, although grazing treatment had little effect on mineral and total soil nitrogen. Interannual variability had a large effect on soil mineral nitrogen, but not on soil organic matter, suggesting that soil nitrogen levels observed in this soil complex may be affected by other indirect pathways, such as climate. The effect of interannual variability in rainfall and the effects of other soil types need to be explored further.

A tradeoff frontier for global nitrogen use and cereal production

Nitrogen fertilizer use across the world’s croplands enables high-yielding agricultural production, but does so at considerable environmental cost. Imbalances between nitrogen applied and nitrogen used by crops contributes to excess nitrogen in the environment, with negative consequences for water quality, air quality, and climate change. Here we utilize crop input-yield models to investigate how to minimize nitrogen application while achieving crop production targets. We construct a tradeoff frontier that estimates the minimum nitrogen fertilizer needed to produce a range of maize, wheat, and rice production levels. Additionally, we explore potential environmental consequences by calculating excess nitrogen along the frontier using a soil surface nitrogen balance model. We find considerable opportunity to achieve greater production and decrease both nitrogen application and post-harvest excess nitrogen. Our results suggest that current (circa 2000) levels of cereal production could be achieved with ∼50% less nitrogen application and ∼60% less excess nitrogen. If current global nitrogen application were held constant but spatially redistributed, production could increase ∼30%. If current excess nitrogen were held constant, production could increase ∼40%. Efficient spatial patterns of nitrogen use on the frontier involve substantial reductions in many high-use areas and moderate increases in many low-use areas. Such changes may be difficult to achieve in practice due to infrastructure, economic, or political constraints. Increases in agronomic efficiency would expand the frontier to allow greater production and environmental gains.

Nitrate–Nitrogen Transport in Horizontal Soil Columns of the Yellow River Delta Wetland, China

AbstractHorizontal movement of nitrate–nitrogen was simulated in horizontal soil columns from a typical tidal flooding wetland and a short‐term flooding wetland of the Yellow River Delta. The primary objectives of this study were to investigate the changes in transport fluxes of nitrate–nitrogen with increasing movement distances and to identify the relationship between transport fluxes of nitrate–nitrogen and water diffusion coefficients. The results showed that the transport fluxes of nitrate–nitrogen were significantly and negatively correlated with movement distances in both wetlands, and decreased exponentially with increasing distances. However, the transport fluxes of nitrate–nitrogen increased exponentially with increasing water diffusion coefficients in both wetlands. The higher transport fluxes of nitrate–nitrogen in surface soils were observed compared to deeper soils, while they were higher in surface soils at the distances near the tracer water head. The findings of this study can contribute to water quality protection by regulating buffer zone width based on the horizontal movement of nitrate–nitrogen.

Investigation of the Biomass and Nutrient Content of Green Manuring Plants as Second Crops in Hungary

The growth, and the development and trends of the nutrient content parameters of three different plant species (Phacelia tanacecifolia,Sinapis alba, Raphanus sativus) grown as secondary crops for green manure, as a function of two different fertiliser doses (0 kg/ha N; 50kg/ha N), was studied under unfavourable site conditions at the Crop Production and Biomass Utilisation Demonstration Centre of theSzent István University, Gödöllő, Hungary. The application of the small, 50 kg/ha dose of nitrogen increased the biomass yield in eachcase, to 2.78-3.11 times that of the control field. The dry matter content of the produce increased only by 2.11-2.66 times, as the watercontent of the green manure plants also increased as a result of the nitrogen supplement. The increased amount of nitrogen boosted theavailability of all of the other macro elements for the plants. In view of the present findings it can be recommend the application of somenitrogen fertiliser in the given site before growing some crop for use as green manure in all cases but where the straw after cereals is left onthe soil surface nitrogen should be applied to alleviate the pentosan effect and to increase the uptake of macro elements.

Nitrogen balances of smallholder farms in major cropping systems in a peri-urban area of Beijing, China

An in-depth understanding of nutrient management variability on the regional scale is urgently required due to rapid changes in cropping patterns and farmers’ resource use in peri-urban areas of China. The soil surface nitrogen (N) balances of cereal, orchard and vegetable systems were studied over a 2-year period on smallholder fields in a representative peri-urban area of Beijing. Positive soil surface N balances were obtained across all three cropping systems. The mean annual N surplus of the vegetable system was 1,575 kg N ha−1 year−1, or approximately 3 times the corresponding values in the cereal (531 kg N ha−1 year−1) and orchard systems (519 kg N ha−1 year−1). In the vegetable system, animal manure (1,443 kg N ha−1 year−1 on average) was the major source of N input (65 % of the total N input) and the factor with strongest impact on the N surplus. In the cereal system, however, about 74 % of the total N input originated from mineral fertilizer application which was the major contributor to the N surplus, while in the orchard system, the N surplus was strongly and positively correlated with both mineral fertilizer and animal manure applications. Furthermore, within each cropping system, N fertilization, crop yields and N balances showed large variations among different smallholder fields, especially in orchard and vegetable systems. This study highlights that differences in farming practices within or among cropping systems should be taken into account when calculating nutrient balances and designing strategies of integrated nutrient management on a regional scale.

Effect of sewage sludge and synthetic fertilizer on pH, available N and P in pasture soils in semi-arid area, Turkey

Activated sewage sludge from the aerobically-digested treatment and synthetic fertilizer were used to determine total N, available P and pH in different soil depth of pasture in semi arid ecological condition, in Van, Turkey. The study was carried out in a completely randomized block. Four treatment of sewage sludge, one treatment of synthetic fertilizer and no treatment as a control were used in two consecutive years. Soil samples were collected from surface soil (0 to 20 cm) and subsoil (20 to 40 cm) 11 months after SS (sewage sludge) and TSP (triple super phosphate) application and 7 months after AN application for both years. By using sewage sludge and synthetic fertilizers treatments, surface and subsoil pH decreased. The decreases of pH in SF and control plots in both soil depths in 2008 were attributed to root biomass. Although, sewage sludge contains less amount of nitrogen than synthetic fertilizer does, it enabled nitrogen detection in both soil depths for a longer time and in a higher amount. While an increase in the amount of nitrogen in surface soil and subsoil was determined in 2007, a decrease in these was determined in 2008 in both depths. Amount of subsoil available phosphorus increased more by sewage sludge applications. However, amount of surface soil available phosphorus increased more by sewage sludge applications in 2007, while it increased more by synthetic fertilizer application in 2008. The lowest pH value, highest amounts of total N and available P was obtained by higher doses of sewage sludge. However, when long time applications and mineralization process were considered, sewage sludge’s dose of 2.5 ton/ha -1 ya -1 can be said to provide more beneficial results than the synthetic fertilization’s highest dose which is suggested for

Optimization of Monitoring Network Point about Total N in Soil in Hangjiahu Plain

In this paper, Monitoring network point about total content of Nitrogen in surface soil was studied on optimization in Hangjiahu plain, based on the geostatistics, variance and linear correlation. And Background of Total N in soil were compared before and after network point optimization. The result showed that sampling density may improve from 1 point/4km2 to 1 point/64km2. this monitoring result of Total N only can reflect spatial distribution of Nitrogen, but can not reveal its actual circumstance. Detailed investigation of the lowest scale must be done if the distribution of Nitrogen in surface Soil wanted to be understood comprehensively. Zhejiang Province had firstly completed multi-purpose geochemical survey for 1:250000 from 2002 to 2005 [1]. Total N content in surface soil was the central task of the survey because high nitrogen content in soil fertility was not only the characteristics of the land but also one of the reasons of non-point source pollution. In order to grasp the overall trend of geochemical in Hangjiahu plain and timely discover the changes about environment quality of soil total N elements, a multi-level environmental geochemistry monitoring network must be promptly established[2]. But it’s a problem needed to be solved immediately by the geological, environmental and agricultural scientists that how to meet the needs of the accuracy of the premise, with a minimum of sampling points to design the best program of distribution, thereby saving time and cost of sampling. At present, most people used properties of soil spatial variability and spatial analysis methods to solve this problem [3].

Three Gorges Project: effects of resettlement on nutrient balance of the agroecosystems in the reservoir area

This paper reports on the effects of human resettlement on the nutrient balance of the agroecosystems in Three Gorges Reservoir Area (TGRA) of China. The analysis used is the OECD (Organisation for Economic Co-operation and Development) ‘Soil Surface Nitrogen Balance Model’ and agricultural statistical data for the county level in 1985–2005. Spatial and temporal changes of nutrient balance and the impacts of resettlement on such changes were examined. The results demonstrate that rural resettlement has significantly increased soil surface nitrogen and phosphorous surplus since 2000. The structural transformation of agricultural activities from grain production to horticulture or forestry should be encouraged, and more people may need to be moved out of the TGRA to reduce nutrient water pollution.

Soil nitrogen status in Tieguanyin tea plantation of Fujian Province

为了解铁观音茶园土壤氮素供应能力, 对福建安溪、永春和华安14个铁观音生产乡镇150个铁观音茶园表土及相应茶叶进行了调查。结果表明: 供试茶园土壤全氮含量处于中低水平, 平均值为0.79 g·kg^-1, 碱解氮含量处于中高水平, 平均值为95.56 mg·kg^-1, 全氮含量与碱解氮含量呈显著正相关。有机质及阳离 子交换量与土壤全氮和碱解氮含量均呈极显著正相关。不同土壤类型全氮含量依次为水稻土改种>黄壤>红 壤>黄红壤>赤红壤, 质地黏重的土壤氮含量较高。茶树新梢氮含量变幅为8.1～141.8 g·kg^-1, 平均值为23.7 g·kg^-1, 与土壤碱解氮含量无显著相关性。土壤碱解氮含量是否能作为茶园土壤供氮能力的指标以及在铁观音茶树的营养诊断时茶树新梢的氮素含量是否能作为茶树缺素的诊断指标有待进一步研究。福建铁观音茶园土壤应注意增施有机肥, 避免过度施用速效氮肥。

Calculating the Soil Surface Nitrogen Balance at Regional Scale: Example Application and Critical Evaluation of Tools and Data

Agro-ecological indicators (AEIs) allow evaluating sustainability for a large number of farms. The SITPAS Information System developed for the agricultural park “Parco Agricolo Sud Milano” (northern Italy) contains detailed farming and cropping systems information for 731 farms that can be used for these analyses. We used the SITPAS database to evaluate N management with an AEI and to evaluate the suitability of the SITPAS data model for this type of applications. The AEI (soil surface N balance) was calculated for each crop at field scale, as the difference between the sum of N inputs (atmospheric depositions, biological fixation, fertilisers, residues from previous crop) and crop N uptake; the results were aggregated at rotation and farm levels. The farming systems with the highest surplus (> 300 kg N ha-1) are dairy, cattle and pig farms, in which chemical N fertilisers are used in addition to animal manures. The crops with the highest surplus are Italian ryegrass and maize (183 and 172 kg N ha-1, respectively), while rice and wheat have the lowest surplus (87 and 85 kg N ha-1). The data model allowed to store and analyse complex information not manageable otherwise; its main limitation was the excessive flexibility, requiring a complicated procedure for the calculations of this example, and the exclusion of most data at the farming systems level (corresponding to 82% of the studied area) for missing, incomplete, out-of-range or inconsistent data. These results suggest to promote actions towards better N management in cropping systems in the Park and to develop simple data models based on minimum data requirements when sustainability evaluations are to be conducted.

Soil surface nitrogen losses from agriculture in India: A regional inventory within agroecological zones (2000–2001)

We present soil surface nitrogen (N) budgets for the agricultural sector of India, calculated as inputs minus outputs over 21 agroecological zones (AEZ), for 2000–2001. Nearly 35.4 Tg N was input from different sources, with output from harvested crops of about 21.2 Tg N. Soil surface N balance for agricultural lands showed a surplus of about 14.4 Tg. Livestock manure constituted 44% of total inputs, followed by 32.5% from inorganic fertilizer, 11.9% from atmospheric deposition and 11.6% from N fixation. Though the N balance was negative in some states, due to aggregation of states in agroecological regions, all regions showed surplus N loads, with a range of about 19–110 kg/ha. The lowest loads were found for AEZ 17 in the Eastern Himalaya, with 19 kg/ha surplus, and the highest surplus N load in AEZ 7 with 111 kg/ha in Deccan plateau and the Eastern Ghats. Temporal trends in fertilizer consumption from 1950–2000 for India suggested a massive increase of ∼47-fold, whereas production of major crops, rice, wheat and maize, increased nearly ∼4.0-, 10- and 6-fold, respectively. Fertilizer consumption patterns were highly concentrated in Tamilnadu (204.6 kg/ha), Haryana (132.0 kg/ha) and Punjab (148.6 kg/ha). The paper addresses the role of agricultural intensification and its implications for water quality in agroecological regions of India.