Soil nitrate-N levels required for high yield maize production in the North China Plain

High profile nitrate-nitrogen (N) accumulation has caused a series of problems, including low N use efficiency and environmental contamination in intensive agricultural systems. The key objective of this study was to evaluate summer maize (Zea mays L.) yield and N uptake response to soil nitrate-N accumulation, and determine soil nitrate-N levels to meet N demand of high yield maize production in the North China Plain (NCP). A total of 1,883 farmers’ fields were investigated and data from 458 no-N plots were analyzed in eight key maize production regions of the NCP from 2000 to 2005. High nitrate-N accumulation (≥172 kg N ha⁻¹) was observed in the top (0–90 cm) and deep (90–180 cm) soil layer with farmers’ N practice during maize growing season. Across all 458 no-N plots, maize grain yield and N uptake response to initial soil nitrate-N content could be simulated by a linear plus plateau model, and calculated minimal pre-planting soil nitrate-N content for maximum grain yield and N uptake was 180 and 186 kg N ha⁻¹, respectively, under no-N application conditions. Economically optimum N rate (EONR) decreased linearly with increasing pre-planting soil nitrate-N content (r ² = 0.894), and 1 kg soil nitrate-N ha⁻¹ was equivalent to 1.23 kg fertilizer-N ha⁻¹ for maize production. Residual soil nitrate-N content after maize harvest increased exponentially with increasing N fertilizer rate (P < 0.001), and average residual soil nitrate-N content at the EONR was 87 kg N ha⁻¹ with a range from 66 to 118 kg N ha⁻¹. We conclude that soil nitrate-N content in the top 90 cm of the soil profile should be maintained within the range of 87–180 kg N ha⁻¹ for high yield maize production. The upper limit of these levels would be reduce if N fertilizer was applied during maize growing season.     

Long-term effect of fertilizer and manure application on soil-carbon sequestration and soil fertility under the wheat–wheat–maize cropping system in northwest China

Maintenance of soil organic carbon (SOC) is important for the long-term productivity of agroecosystems. An investigation was conducted to study the effects of long-term application of inorganic fertilizers and farmyard manure (FYM) on soil organic carbon (SOC), nitrogen, phosphorus, and potassium nutrient content, water-stable aggregate distribution, and aggregate-associated carbon in a field experiment started in 1982 in an arid region of northwest China. Application of inorganic fertilizer alone (N, NP, or NPK treatments) did not increase SOC concentrations compared with no application of fertilizers (CK) and SOC concentration was significantly reduced, by 18% on average, compared with the initial value at the beginning of the experiment. Application of imbalanced inorganic fertilizer (N and NP), especially, resulted in a significant decrease in available phosphorus and potassium nutrients at a depth of 20 cm. This indicates that long-term application of inorganic fertilizers were inadequate to maintain levels of SOC and nutrients under conventional management with no aboveground crop residues returning to the soil. Long-term application of FYM alone or combined with inorganic fertilizers (M (FYM), MN, MNPK, or MNPK treatments), however, improved SOC and total nitrogen concentrations from initial values of 12.1 and 0.76 g kg⁻¹, respectively, to 15.46 and 1.28 g kg⁻¹, on average, and also enhanced available nitrogen, phosphorus, and potassium concentrations by 47, 50, and 68%, respectively, during the 23-year period. Treatment with FYM resulted in a 0.48 mm greater average mean weight diameter (MWD) of aggregates and a higher percentage of macro-aggregates (>2 mm) and small macro-aggregates (2–0.25 mm) than treatment without FYM. The MWD increased with increasing SOC concentration (R ²=0.75). The SOC concentration was highest in small macro-aggregates, intermediate in macro-aggregates, and lowest in micro-aggregates (0.25–0.05 mm). Approximately 54–60% of total SOC was stored in micro-aggregates (0.25–0.05 mm) and sand+silt fractions (<0.05 mm) after treatment without FYM but 57–64% of total SOC was stored in macro-aggregates (>0.25 mm) after treatment with FYM. MNPK treatment had the greatest effect on improving the levels of SOC and NPK nutrients and in enhancing the formation and stability of macro-aggregates.     

Nitrogen losses from fertilizers applied to maize, wheat and rice in the North China Plain

Ammonia volatilization, denitrification loss and total nitrogen (N) loss (unaccounted-for N) have been investigated from N fertilizer applied to a calcareous sandy loam fluvo-aquic soil at Fengqiu in the North China Plain. Ammonia volatilization was measured by the micrometeorological mass balance method, denitrification by the acetylene inhibition – soil core incubation technique, and total N loss by ¹⁵N-balance technique. Ammonia loss was an important pathway of N loss from N fertilizer applied to rice (30–39% of the applied N) and maize (11–48%), but less so for wheat (1–20%). The amounts of unaccounted-for fertilizer N were in the order of rice > maize > wheat. Deep placement greatly reduced ammonia volatilization and total N loss. Temperature, wind speed, and solar radiation (particular for rice), and source of N fertilizer also affect extent and pattern of ammonia loss. Denitrification (its major gas products are N₂ and N₂O) usually was not a significant pathway of N loss from N fertilizer applied to maize and wheat. The amount of N₂O emission (N₂O is an intermediate product from both nitrification and denitrification) was comparable to denitrification loss for maize and wheat, and it was not significant in the economy of fertilizer N in agronomical terms, but it is of great concern for the environment.     

Gross mineralization, nitrification and N2O emission under different tillage in the North China Plain

No-tillage cropping can increase soil carbon (C) stocks and aggregation, and subsequently impact the internal nitrogen (N) cycle and gas loss. The ¹⁵N pool dilution method was used to study gross N transformations, and relative proportions of nitrous oxide (N₂O) emissions derived from denitrification versus nitrification-related processes under long-term tillage systems (no-tillage, rotary tillage and conventional tillage) in the North China Plain. In-field incubation experiments were repeated in successive growing seasons during April?CNovember in 2007. Gross mineralization rates for rotary and mouldboard plough tillage (3.6?±?0.3?C10.6?±?1.5?mg?N?kg^?1?days^?1) were significantly higher than for no-tillage (1.7?±?0.8?C6.8?±?1.1?mg?N?kg^?1?days^?1). Gross mineralization was positively correlated with soil moisture and temperature, as well as with microbial biomass N and C. However, there was no consistent tillage effect on gross nitrification, and gross nitrification was positively correlated with soil moisture, but not with gross mineralization and microbial biomass. N₂O emissions were higher in no-tillage (NT) than for conventional tillage (CT) during May?CAugust. The ¹⁵N labelling indicated that 26?C92?% of the N₂O was directly derived from the soil ammonium (NH₄ ⁺) pool. Emission rates of N₂O from both nitrification and denitrification were positively correlated with NH₄ ⁺ supply as expressed by gross mineralization, but not correlated with supply of nitrate as expressed by gross nitrification. The fraction of nitrified N emitted as N₂O was positively correlated with changes in soil moisture and varied within 0.01?C2.51???. Our results showed that the tillage management impact on gross N transformation was not consistent with N₂O emission, and more detailed information on the controls over N₂O formation needs to be sought.     

Use of the open-path TDL analyzer to monitor ammonia emissions from winter wheat in the North China Plain

The backward Lagrangian stochastic (BLS) model and open-path tunable diode laser (OPTDL) analyzer were used to monitor ammonia (NH₃) emissions from urea applied to winter wheat in the North China Plain. The high-temporal resolution measurements of ammonia concentrations provided an opportunity for estimating the diel patterns of ammonia emissions, as well as valuable information about the factors that influence NH₃ emissions. The results showed both large diel variability and daily variability in NH₃ volatilization, with NH₃ emissions highest during the daytime. The diel pattern of ammonia volatilization depended mainly on the diel variation of wind speed and soil temperature, while the overall pattern of NH₃ loss was strongly affected by soil moisture content, soil NH₄ ⁺-N concentration, wind speed and soil temperature. At the end of the measurement period, the cumulative NH₃ loss was 12.21–16.43 kg N ha^?1, calculated based on different time scale average Q _BLS. Due to sensitivity of the OPTDL analyzer, the estimated total ammonia loss was still doubtful in this study.     

Optimizing soil nitrogen balance in a potato cropping system through legume intercropping

Nutrient Cycling in Agroecosystems - Negative nitrogen balance represents a major factor causing low potato yield in potato growing areas of Kenya while its excessive surplus poses a significant...     

Partial balance of nitrogen in a maize cropping system in humic nitisol of Central Kenya

The application of nitrogen in a soil under agricultural production is subject to several pathways including de-nitrification, leaching and recovery by an annual crop. This is as well greatly influenced by the management practices, nitrogen source and soil conditions. The main objective of this study was to investigate the loss of nitrogen (N) through nitrous oxide (N₂O) emissions and mineral N leaching and uptake by annual crop as influenced by the N source. The study was carried out at Kabete in Central Kenya. Measurements were taken during the second season after two seasons of repeated application of N as urea and Tithonia diversifolia (tithonia) leaves. Results obtained indicated that nitrous oxide (N₂O) emissions at 4 weeks after planting were as high as 12.3 μg N m ⁻² h⁻¹ for tithonia treatment and 2.9 μg N m⁻² h⁻¹ for urea treatment. Tithonia green biomass treatment was found to emit N₂O at relatively higher rate compared to urea treatment. This was only evident during the fourth week after treatment application.Soil mineral N content at the end of the season increased down the profile. This was evident in the three treatments (urea, tithonia and control) investigated in the study. Urea treatment exhibited significantly higher mineral N content down the soil profile (9% of the applied N) compared to tithonia (0.6% of the applied N). This was attributed to the washing down of the nitrate-N from the topsoil accumulating in the lower layers of the soil profile. However, there was no significant difference in N content down the soil profile between tithonia treatment and the control. It could be concluded that there was no nitrate leaching in the tithonia treatment. Nitrogen recovery by the maize crop was higher in the urea treatment (76% of the applied N) as compared to tithonia treatment (55.5% of the applied N). This was also true for the residual mineral N in the soil at the end of the season which was about 7.8% of the applied N in the urea treatment and 5.2% in the tithonia treatment.From this study, it was therefore evident that although there is relatively lower N recovery by maize supplied with tithonia green biomass compared to maize supplied with urea, more nitrogen is being lost (through leaching) from the soil–plant system in the urea applied plots than in tithonia applied plots. However, a greater percentage (37.8%) of the tithonia-applied N could not be accounted for and might have been entrapped in the soil organic matter unlike urea-applied N whose greater percentage (92%) could be accounted for.     

Sustainable agriculture in the tropics: the case of potassium under maize cropping in Togo

The transfers of native and applied K in a rhodic Ferralsol were studied in an agrosystem of southern Togo to propose sustainable cultivation strategies for K in kaolinitic soils. Potassium balance was measured over two years in field conditions under continuous maize cultivation with two K fertilisation levels (0 and 137 kg K ha^–1 yr^–1). Postassium leaching below the root zone, determined using ceramic cup samplers and Darcy's law, was on average 7.5 kg K ha^–1 yr^–1 with K fertilisation, i.e. 2% of the quantity of K applied, and 4.5 kg K ha^–1 yr^–1 without. The low leaching values resulted from a K concentration lower than 130 M in the soil solution. The low K concentration in the soil solution was related to selective adsorption of K increased by a low content of exchangeable K, with a Gapon selectivity coefficient ranging from 7.9 and 11.5 M ^–0.5. So the level of exchangeable K must first be increased to raise K concentration in the soil solution. The fixation and release of K was analysed using the isotopic exchange method with ⁴²K-ions and compartmental analysis of the kinetics of isotopic exchange. Potassium fixed in a form non available within one year accounted for 78% of the difference between the two treatments. The annual amount of K fertilisation must thus be based on the quantity of K removed in the grain and crop residues, with an extra addition to account for K fixation. Given a crop residue content of 85 kg K ha^–1 yr^–1 in the fertilised treatment, the return of crop residues is essential if sustainability is to be achieved with traditional cropping systems where little K fertiliser is added.     

Phosphorus transformation in a soybean-cropping system in Andosol: effects of winter cover cropping and compost application

Understanding phosphorus (P) transformation is necessary to develop sustainable P management practices on Andosol with large P-fixing capacity. This study was conducted during 2005–2007 in northeastern Japan to determine how the amounts of inorganic P (P_i) and organic P (P_o) fractions change in a Silandic Andosol under soybean production [Glycine max (L.)]. Two treatments were examined: application of composted cattle manure (0 (P0), 61 (P1), and 122 or 183 (P2) kg P ha⁻¹ year⁻¹) and winter cover cropping (no cover crop, rapeseed [Brassica napus], and cereal rye [Secale cereale L.]). Compost was applied before soybean seeding; cover crops were seeded after soybean harvest without further fertilization. Soil P was extracted sequentially with anion exchange resin (P_i), 0.5M NaHCO₃ (P_i, P_o), 0.1M NaOH (P_i, P_o), and 0.5M H₂SO₄ (P_i). Soybean removed 42.3 and 48.5 kg P ha⁻¹ (only 23 and 10% of the added P), respectively, in P1 and P2. In the P2 soil, 64% of excess P was distributed into P_i fractions, mainly resin-P_i and NaOH–P_i (29 and 19%, respectively). In P0, despite no P addition, soybean removed 41.5 kg P ha⁻¹ concurrently with a decrease in NaOH–P_i, suggesting its potential contribution to soybean P uptake. Neither of cover crops had significant effect on soil P fractions during the 3 year period.     

种植结构调整对化肥消费的影响

我国加入 WTO后 ,种植业结构将发生巨大变化 ,这将影响化肥的消费。根据农户作物施肥的调查数据 ,讨论种植结构对化肥消费状况的影响。结果表明 ,种植结构变化对施肥及肥料分配均产生很大影响 ,随着蔬菜瓜类和果树的种植面积扩大 ,总体上将增加单位面积投肥量及化肥总需求量 ,提高磷钾消费比率和复合肥使用比例 ,但会大幅度降低粮食作物化肥消费比率。     

Changes in soil available NPK in multiple cropping systems based on short duration sugarcane crops relative to a conventional sugarcane cropping system

Changes in soil available NPK were studied in four intensive crop rotations based on short duration (8 months) sugarcane crops (1. short duration plant cane/1st ratoon/2nd ratoon; 2. short duration plant cane/1st ratoon/finger millet/cotton; 3. finger millet/short duration plant cane/1st ratoon/wheat; and 4. finger millet/maize/short duration plant cane/1st ratoon). These rotations were compared with the conventional duration (12 months) sugarcane crop sequence (one plant + one ratoon) in a cycle of 24 months.Soil available nitrogen (SAN) declined when 100 or 150 kg N ha^–1 was applied in the short duration sugarcane based systems, but was either maintained or improved at a higher N application rates (200 or 250 kg ha^–1). The conventional system showed a sharp decline in SAN of about 14% from its original status at the end of the sequence. Close row spacing (60 cm) of sugarcane improved the soil N level over that in the conventionally spaced rows (90 cm) probably through greater rhizosphere biomass additions.Available P declined sharply from its original level in the soil in sequence 2, the decline being marked after cotton. In all the other short duration based sequences it was maintained. The conventional system also showed reduced soil available P at the end of the sequence. Soil available K declined in all crop sequences.Nitrogen uptake was far less than additions made by fertilizer. The actual soil N balance was much lower than the expected balance thus indicating large losses of N from the soil. Phosphorus removal was also less than the additions made and thus there were improvements in the soil available P status at the end of the crop cycle. In all the sequences, there was a negative potassium balance due to greater removal by the various crops when compared to K additions. However, in the system as a whole there were net gains of K as larger amounts were recovered than had been added.     

Modeling farm nutrient flows in the North China Plain to reduce nutrient losses

Years of poor nutrient management practices in the agriculture industry in the North China Plain have led to large losses of nutrients to the environment, causing severe ecological consequences. Analyzing farm nutrient flows is urgently needed in order to reduce nutrient losses. A farm-level nutrient flow model was developed in this study based on the NUFER (NUtrient flows in Food chains, Environment and Resources use) model, and was used to analyze nitrogen (N) and phosphorus (P) flows, use efficiencies, and losses for nine representative farm types in the North China Plain. Data from 401 farms were evaluated for the years 2012–2015. The analysis showed that mixed farms were more efficient in nutrient utilization than crop-based or landless livestock farms. The efficiencies of N and P used in crop production were highest for mixed dairy farms, reaching 67% for N and 68% for P. Consistently, mixed dairy farms had the lowest N and P surpluses and losses in crop production. Mixed swine farms were 5 and 9% higher in N and P efficiency in livestock production than landless swine farms, respectively. Losses of N and P from the animal manure management chain were 20–42% lower for mixed swine and 69–78% lower for mixed poultry farms than for landless farms of the same animal type. This is at least partially due to more frequent manure removal. Integrated crop-livestock production using livestock wastes as crop fertilizer was shown to be the most sustainable model in nutrient use for the agriculture industry in the North China Plain.     

Predicting the site specific soil N supply under winter wheat in Germany

The expected amount of plant nitrogen (N) at harvest which originates from soil N supply is of high relevance for N fertilization planning. Due to mineralization–immobilisation turnover processes, soil N supply is influenced by N fertilization which complicates its assessment. The soil N supply consists of two components: the soil mineral N measured at early spring and the ‘effective’ N mineralization (Min^eff) under winter wheat (Triticum aestivum L.). Min^eff was defined as the difference between crop N uptake (N^crop) at harvest and N supply. Our aim was the identification and quantification of climate and site-related factors in order to achieve an improved assessment of the site-specific (long term average) Min^eff. We used N rate experiments from 411 collective seasons, carried out at 98 sites across Germany in order to analyze the impact of climate and site-related factors on Min^eff. Quadratic curves were fitted in order to describe the grain N uptake as a function of N supply. A fixed marginal N efficiency was defined in order to analyze Min^eff at a reasonable N supply. Starting with estimates for Min^eff as function of preceding crop, we found that climate (average temperature during May, annual rainfall) and site-related factors have a significant influence on Min^eff. In order to ensure that the regression model is transferable to unknown sites, a “leave one site out” cross validation was carried out. Compared to considering preceding crop only (reference), the regression model reduced the RMSE by 9.5 (calibration) or 8.3 (cross validation) kg N/ha.     

Nitrogen leaching in an upland cropping system on an acid soil in subtropical China: lysimeter measurements and simulation

The effect of rainfall and nitrogen (N) input on nitrate leaching in a rain-fed peanut–oilseed rape system on an acidic soil in subtropical China was investigated in a field lysimeter experiment from 1997 to 2000. Drainage and nitrate leaching were simulated using the Water and Nitrogen Management Model (WNMM). Nitrate concentrations in the drainage water and nitrate leaching increased with increasing N application rate. Annual leaching losses ranged from 21.1 to 46.3 kg N ha⁻¹ (9.5–16.8%) for inputs between 0 and 150 kg N ha⁻¹. Growth of oilseed rape decreased the nitrate concentration in the drainage water, but growing N fixing peanuts did not. Rainfall had a greater impact on nitrate leaching than crop uptake. Nitrate concentrations in the drainage water were relatively low (1.95–4.33 mg N l⁻¹); this was caused by the high precipitation, the low nitrification rate, and the low residual nitrate in the soil. The loss of nitrate was low during the dry season (October–February) and in the dry year (rainfall 17% below average) mainly as a result of reduced drainage. WNMM satisfactorily simulated the inter-monthly variation in drainage and total nitrate leached, with respective relative root mean square errors of 42.7% and 70.2%, mean modelling efficiencies of 0.88 and 0.67, and mean relative errors of −3.82% and 21.8%. The modelled annual N losses were only 1–7% less than the observed values.     

A mathematical model for predicting the soil nitrogen status under varying fertilizer practices in a continuous cropping sequence

A mathematical model has been proposed for predicting the changes in soil nitrogen status due to continuous fertilization in a continuous cropping sequence. The model also enabled the prediction of the steady state of soil nitrogen for a specified fertilizer practice.The model was applied to six years nitrogen availability data of four fertilizer practices in finger millet-maize-cowpea sequence followed in the Long Term Fertilizer Experiments conducted at Tamil Nadu Agricultural University, Coimbatore, India. The agreement between the predicted soil nitrogen status by the model and the actuals was proved by employing reliability index.     

Crop response of aerobic rice and winter wheat to nitrogen,phosphorus and potassium in a double cropping system

In the aerobic rice system, adapted rice cultivars are grown in non-flooded moist soil. Aerobic rice may be suitable for double cropping with winter wheat in the Huai River Basin, northern China plain. Field experiments in 2005 and 2006 were conducted to study the response of aerobic rice and winter wheat to sequential rates of nitrogen (N), phosphorus (P) and potassium (K) in aerobic rice—winter wheat (AR-WW) and winter wheat—aerobic rice (WW-AR) cropping sequences. Fertilizer treatments consisted of a complete NPK dose, a PK dose (N omission), a NK dose (P omission), a NP dose (K omission), and a control with no fertilizer input. Grain yields of crops with a complete NPK dose ranged from 3.7 to 3.8 t ha⁻¹ and from 6.6 to 7.1 for aerobic rice’ and ‘winter wheat’, respectively. N omissions caused yield reductions ranging from 0.5 to 0.8 t ha⁻¹ and from 1.6 to 4.3 t ha⁻¹ for rice and wheat, respectively. A single omission of P or K did not reduce rice and wheat yields, but a cumulative omission of P or K in a double cropping system significantly reduced wheat yields by 1.2–1.6 t ha⁻¹. N, P and K uptake of both crops were significantly influenced by fertilizer applications and indigenous soil nutrient supply. Nutrient omissions in a preceding crop reduced plant N and K contents and uptake additionally to direct effects of the fertilizer treatments in wheat, but not in rice. Apparent nutrient recoveries (ANR) differed strongly between ‘aerobic rice’ and ‘winter wheat’; in rice: for N it ranged from 0.30 to 0.32, for P from 0.01 to 0.06, and for K from 0.03 to 0.19 and in wheat: for N from 0.49 to 0.71, for P from 0.09 to 0.15, and for K from 0.26 to 0.31. Further improvements of crop productivity as well as nutrient-use efficiencies, should be brought about by developing cropping systems, by an appropriate choice of adapted cultivars, by a site- and time-specific fertilizer management and by eliminating other yield-limiting factors. It is concluded that nutrient recommendations should not be based on the yield response of single crops only, but also on the after-effects on nutrient availability for succeeding crops. A whole cropping system approach is needed.     

Spatial and temporal nitrogen applications for winter wheat in a loamy soil in south-eastern China

Split application of nitrogen (N), applied by broadcasting, is both time consuming and inconvenient; yet it is widely practised for wheat. Simplified N fertilization is necessary for wheat in south-eastern China. One-time band application was compared with split application using three doses of N (150, 195, and 240 kg ha^?1) in 2014/2015 and 2015/2016. Grain yield and N-use efficiency of winter wheat were determined over two consecutive seasons. A corresponding micro-plot trial using ¹⁵N-labelled urea was conducted only in 2015/2016 to measure the fate of urea-¹⁵N. The two methods showed no difference in grain yield, except at 240 kg ha^?1 of N in 2014/2015. The average grain N concentration (18.2 g kg^?1) was slightly lower in band application than that in broadcast application (19.2 g kg^?1), but there was no significant difference (P > 0.05). In 2014/2015, N apparent recovery efficiency ranged from 33.1 to 49.9%; N agronomic efficiency, from 8.9 to 38.9 kg kg^?1; and N partial factor productivity, from 23.6 to 38.4 kg kg^?1. In 2015/2016, the corresponding values were 29.4–38.6%, 13.5–38.6, and 24.3–33.9 kg kg^?1. In the micro-plot trial, compared to split application, fertilizer N recovery in winter wheat in one-time band application was lower by 26.5% and increased the unaccounted-N loss by 21.7%. Thus, considering environmental impacts, one-time band application of N at sowing is not a suitable alternative to broadcast application in split doses for winter wheat in the loamy soils of south-eastern China.     

The significance of available nutrient fluxes in N and P budgets for maize cropping on a Rhodic Kandiustox: a study with compost,NP fertilizer and stubble removal

Nutrient budgets may be useful tools for nutrient management of crops especially if they estimate the nutrient fluxes available from a variety of sources including organic and inorganic fertilizer, crop residues and soil organic matter. The aim of the present study was to develop a budget of available nutrients by determining the contribution of mineralized nutrient fluxes and fertilizer input relative to nutrient losses and removal in harvested products in the overall N and P balances. N and P inputs and outputs and available N and P fluxes in the soil were estimated for 3 consecutive maize crops where inputs and outputs were altered by NP fertilizer, compost and stubble removal on a Rhodic Kandiustox. A sensitivity analysis of calculated and measured nutrient budget items was conducted to identify the main factors affecting the accuracy of the nutrient balance calculations. Mineral fertilizer rate was the major factor for maize nutrient budgets as shown by its contribution to N and P balances. Without mineral fertilizer application, soil organic matter (SOM) mineralization was the most important within-season nutrient input. In the case of N, shoot uptake was the main output followed by denitrification. Phosphorus adsorption by the soil was the major P output from the available pools followed by shoot uptake. SOM mineralization maintained the pools of available N and P if stubble of the previous crop was returned. Mineral fertilizer application, which produced surplus balances of N and P, would however, be needed to attain high yield, even with stubble return. The available N and P from compost were not significant inputs in the nutrient balances until year 3. Total N and resin extractable P in soil after five crops supported the calculated nutrient balances indicating the importance of available nutrient fluxes in calculating N and P balances.