Compositional nutrient diagnosis and main nutrient interactions in yellow pepper grown on desert calcareous soils

Mineral‐nutrient stress is one of the main factors limiting crop production, especially in arid lands. The mineral requirement of a crop is difficult to determine, and the interpretation of foliar chemistry composition is not easy. This study was conducted to compute the minimum yield target for fresh fruit of yellow pepper (Capsicum annuum L.) and the corresponding Compositional Nutrient Diagnosis (CND) as well as to identify significant nutrient interactions of this crop in desert calcareous soils. Preliminary CND norms were developed using a cumulative variance‐ratio function and the chi‐square distribution function. From a small database, we computed means and standard deviations of row‐centered log ratios, V_X, of five nutrients (N, P, K, Ca, and Mg) and a filling value, R, which comprises all nutrients not chemically analyzed and quantified them in 54 foliar samples of the popular yellow pepper cv. ‘Santa Fé’. This cultivar is widely grown in northwest Mexico under arid conditions. These norms are associated to fresh fruit yields higher than 15.04 t ha^–1. Principal‐component analyses, performed using estimated CND nutrient indexes, allowed us to identify four interactions: negative P‐Ca, P‐Mg, and N‐K, and positive Ca‐Mg. Pepper plants growing on calcareous soils tend to take up more Ca and Mg than considered as optimum in other soil conditions.     

Optimum Nutrient Concentrations and CND Scores of Mature White Spruce Determined Using a Boundary-Line Approach and Spatial Variation of Tree Growth and Nutrition

ABSTRACT

Standards of optimum nutrition are not readily available for mature trees of the Canadian boreal forest. The objective of this study was to determine foliar nutritional standards for white spruce for all major nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and manganese (Mn)] using critical values (CVA) and compositional nutrient diagnosis (CND). Trees were sampled at two locations in Ontario and Quebec to cover a gradient of soil fertility levels. A boundary-line approach was used in combination with quadratic regression models to estimate the relationship between growth and foliar-nutrient concentrations or CND scores when free of the effects of interacting environmental factors. White spruce optimum nutrition ranges were computed from significant relationships (P ≤ 0.10) for N, P, K, Ca, and Mn concentrations and for N, P, and K CND scores. Optimum concentrations for first-year needles were 12.3, 1.9, 7.3, 6.5, and 0.39 mg g^?1 for N, P, K Ca, and Mn, respectively, whereas optimum CND scores were 0.17, ?1.65, ?0.40, and ?0.30 for N, P, K, and Ca, respectively. Samples from a broader range of environmental conditions will be required in order to establish standards for all major nutrients and to ascertain toxicity levels of most nutrients.     

Role of Nutrient Imbalance on Yellow Leaf Disease in Smallholder Arecanut Systems on a Laterite Soil in India

On-farm trials in India investigated the role of nutrient imbalance on yellow leaf disease (YLD) in arecanut on a laterite soil using compositional nutrient diagnosis (CND) approach. Soil fertility status was imbalanced with high organic carbon status and low phosphorus (P) and potassium (K). The CND norms indicated that the order of nutrient demand was changed with nutrient application. Interventions increased yield by 50% during 2007–2010. The correlations indicated positive effect of nitrogen (N) and K and negative effect of manganese (Mn) on yield. The CND indices for NPK were important discriminators between yellowed and apparently healthy populations both in 2007 and 2010. Linear regressions between leaf nutrient concentrations and CND indices were significant for P, K, iron (Fe), Mn, and copper (Cu) (R² = 0.44–0.53). Results suggest that the predisposing factor for YLD might be nutrient imbalance in the soil leading to deficit of major nutrients in plant.     

Broiler Litter as a Sole Nutrient Source for Cotton: Nitrogen,Phosphorus, Potassium,Calcium, and Magnesium Concentrations in Plant Parts

Abstract

The ability of poultry litter to support plant growth by supplying essential plant nutrients in the absence of other sources of the nutrients has not been studied thoroughly. The objectives of this research were to (1) determine the ability of poultry litter, as the sole nutrient source, to provide macronutrients and support growth of cotton (Gossypium hirsutum L.) (2) evaluate the distribution of these nutrients within the different plant parts, and (3) estimate the efficiency with which these nutrients are extracted by cotton. The research was conducted in plastic containers filled with a 2:1 (v/v) sand:vermiculite growing mix under greenhouse conditions. The treatments included broiler litter rates of 0, 30, 60, 90, or 120 g pot^?1 with or without supplemental Hoagland's nutrient solution. Broiler litter supplied adequate amounts of the macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) and supported normal growth of cotton. Tissue nutrient analysis showed that the concentration of N, P, K, and Mg in the upper mainstem leaves was within published sufficiency ranges for cotton growth. Evaluation of the N distribution indicated that the cotton plant partitions N to reproductive parts when faced with deficiency of this nutrient and favors allocating N to new leaf growth once the requirement for reproductive growth is met. The partitioning of P was similar to that of N but less distinct. Cotton extracted Mg and K with greater efficiency (up to 58%) than the other nutrients and stored these nutrients in older leaves. The extraction efficiency of N ranged between 21% at 120 g pot^?1 litter and 27% at 30 g pot^?1 litter. Phosphorus was the most poorly extracted nutrient, with only 16% of the total applied P extracted when 30 g pot^?1 litter was applied and only 6% extracted at the higher litter rates. This suggests that the same problem of P buildup that has been reported in soils under pasture may also occur when poultry litter is repeatedly applied to the same soil planted to cotton. These results show that broiler litter not only supplied enough N but also supplied the four other macronutrients (P, K, Ca, and Mg) in amounts sufficient to support normal cotton growth. This research implies that poultry litter can effectively substitute for several fertilizers to meet crop macronutrient (N, P, K, Ca, and Mg) needs in soils deficient in any or all of these nutrients.     

Effect of Potassium Supplies on the Nutritional Status of Maize (Zea mays L.)

The effect of soil potassium (K) supplies on the yield and nutritional status of maize and on interactions between the nutrients was examined in a long-term mineral fertilization experiment on maize. The experiment was set up in 1989 in Hungarian Great Plain, Szarvas on chernozem meadow soil calcareous in the deeper layers, with four levels each of nitrogen (N), phosphorus (P) and potassium (K) supplies. The present paper describes the results of K fertilization in the 7–19th years of the experiment, from 1996 to 2008. The ammonium (NH₄)-lactate (AL) potassium oxide (K₂O) content of the ploughed layer ranged from 200 to 550 mg kg^–1 depending on the K fertilization level. No significant yield surpluses were recorded in any of the 13 years in response to the better K supplies ensured by K fertilizer. The results of leaf analysis indicated that the K concentrations representing satisfactory K supplies at a grain yield level of 10–14 t ha^–1 were 2.3–4.3% at the 5–6-leaf stage and 1.5–2.6% at the beginning of tasselling. When the AL-K₂O content of the soil was above 200–320 mg kg^–1, K– calcium (Ca), K–magnesium (Mg) and K–copper (Cu) antagonism was observed in the nutrient concentrations of the maize leaves in most years. The limit values of satisfactory nutrient supplies for maize in the 5–6-leaf stage and at the beginning of tasselling were 0.25–0.60% for Ca, 0.15–0.40% for Mg, and 7–11 mg kg^–1 and 2–11 mg kg^–1, respectively, for Cu. In dry years the iron (Fe) and zinc (Zn) concentrations of maize leaves declined at higher soil K supply levels.     

Genotypic variation in foliar nutrient concentrations, δ13C,and chlorophyll fluorescence in relation to tree growth of radiata pine clones in a serpentine soil

This study investigated the genotypic variation in foliar nutrient concentrations, isotopic signature (δ¹³C), and chlorophyll fluorescence (F_v/F_m) and tree growth of 40 radiata pine clones grown on a New Zealand serpentine soil, and the relationships between growth and physiological traits of these clones from improved and unimproved groups. Genotypic variation in growth and physiological traits existed within (i.e., clonal) and between groups, with larger variation among clones. The clonal repeatabilities were greater for foliar nitrogen (N), calcium (Ca), magnesium (Mg), boron (B) concentrations, δ¹³C, and Ca : Mg ratio (0.35–0.64) than for growth traits (0.14–0.27) and other physiological traits (0.08–0.24). Significant phenotypic correlations were found between growth traits and foliar phosphorus (P), potassium (K), sulfur (S), iron (Fe), and K : Mg and Ca : Mg ratios and F_v/F_m (positive), and foliar Mg (negative). This study indicates that the trees on this serpentine soil generally suffered from multiple nutrient deficiencies and imbalances and the clonal variation in growth performance was more related to their capabilities of acclimation to nutrient than water stresses. Overall, the clones that absorbed more P, K, S, and Fe and less Mg from the soil grew better on this serpentine soil. For unimproved clones, the most limiting nutrients for tree growth were foliar K and Fe, while for improved clones it was foliar K.     

Soil fertility and yield-limiting nutrients in oil palm plantations of north-eastern state Mizoram of India

A survey was conducted for assessment of soil fertility status, leaf nutrient concentration and finding yield-limiting nutrients of oil palm (Elaeis guineensis Jacq.) plantations in Mizoram state situated in the northeastern part of India. Soil pH, electrical conductivity (EC), organic carbon (OC), available potassium (K), available phosphorus (P) (Bray's-P), exchangeable calcium (Ca) (Exch. Ca) and magnesium (Mg) (Exch. Mg), available sulfur (S) (CaCl₂-S), and hot-water-soluble boron (B) (HWB) content in surface (0–20 cm depth) and subsurface (20–40 cm depth) soil layers varied widely. Diagnosis and Recommendation Integrated System (DRIS) norms were established for different nutrient expressions, and DRIS indices were computed. As per DRIS indices, the order of requirement of nutrients was found to be B > K > Mg > P > nitrogen (N). Optimum leaf nutrient ranges as per DRIS norms varied from 1.91% to 2.95%, 0.46% to 0.65%, 0.63% to 1.00%, 0.48% to 0.88%, and 9.41 to 31.0 mg kg^?1 for N, P, K, Mg, and B, respectively. On the basis of DRIS-derived optimum ranges, 32%, 9%, 27%, 12%, and 12% leaf samples had less than optimum concentration of N, P, K, Mg, and B, respectively. The optimum ranges developed could be used as a guide for routine diagnostic and advisory purpose for efficient fertilizer application.     

DEVELOPMENT AND APPLICATION OF CVA,DRIS, AND CND NORMS FOR THREE HYBRIDS OF POPULUS MAXIMOWICZII PLANTED IN SOUTHERN QUEBEC

Plantations of hybrid poplars adapted to relatively poor soils and cold conditions are being established in abandoned fields and forest sites in southern Quebec. Hybrids of Populus maximowiczii are well adapted to these sites but little is known about their nutritional requirements. The objectives of this study were to develop nutritional norms (CVA, DRIS, CND) for three of these hybrids: 915508, Populus euramericana or canadensis X Populus maximowiczii; 3729, Populus nigra X Populus maximowiczii; and 915303, Populus maximowiczii X Populus balsamifera, and to apply the norms on some sites recently planted in southern Quebec. Six plantations (two per clone) were used for the determination of nutritional norms. In each plantation, individual trees were fertilized with nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) according to a factorial design with three levels of application for each nutrient (3⁵ = 243 treatments). Tree diameter and height, unit foliar mass and foliar chemistry (N, P, K, Ca, and Mg) of each tree were determined two years after fertilization. CVA, DRIS and CND norms were determined using a boundary-line approach with each plantation. Nutritional norms could be established for most combinations of clones and nutrients. CVA, DRIS and CND indices produced with published optimum nutrient concentrations for hybrid poplars closely related to P. maximowiczii were generally in agreement with the ones developed in our study. Differences in nutritional norms among P. maximowiczii hybrids/clones were small but hybrid/clone specific norms could provide more precise estimates of tree nutrition. The application of the norms on some representative sites of southern Quebec revealed more frequent nutrient imbalances than true nutrient deficiencies with generally excessive Ca and Mg, and limiting N, P, and K.     

Effects of nutrients omission on maize growth and nutrient uptake in three dominant soil types of southwestern Nigeria

Abstract

A pot experiment was conducted to determine most limiting nutrients for maize performance using nutrient omission treatments in three soil types of southwestern Nigeria. There were six treatments; full nutrient [120?kg nitrogen (N)/ha, 40?kg phosphorus (P)/ha, 80?kg potassium (K)/ha, 10?kg molybdenum (Mo)/ha, and 5?kg zinc (Zn)/ha]; full nutrient minus N, P, K, Mo, and Zn including control was replicated thrice. Treatments were arranged as split plot in a complete randomized design. Data were collected on growth parameters, shoot, root dry weights, and NPK uptakes. Data were subjected to analysis of variance and means separated using LSD_0.05. Majeroku and Egbeda soils and full nutrient supported better maize growth and NPK uptakes. Shoot weight was higher in Egbeda while root weight was higher in Itagunmodi soil. Phosphorus was the most limiting in Egbeda and Itagunmodi soils, and nitrogen in Majeroku soil. In conclusion, maize growth, nutrient uptake and most limiting nutrient varied with soil types.     

Nutrient storage in termite (Macrotermes bellicosus) mounds and the implications for nutrient dynamics in a tropical savanna Ultisol

The role of mounds of the fungus-growing termite Macrotermes bellicosus (Smeathman) in nutrient recycling in a highly weathered and nutrient-depleted tropical red earth (Ultisol) of the Nigerian savanna was examined by measuring stored amounts of selected nutrients and estimating their rates of turnover via the mounds. A study plot (4?ha) with a representative termite population density (1.5?mounds?ha^?1) and size (3.7?±?0.4?m in height, 2.4?±?0.2?m in basal diameter) of M. bellicosus mounds was selected. The mounds were found to contain soil mass of 9249?±?2371?kg?ha^?1, composed of 7502?±?1934?kg?ha^?1 of mound wall and 1747?±?440?kg?ha^?1 of nest body. Significant nutrient enrichment, compared to the neighboring topmost soil (Ap1 horizon: 0–16?cm), was observed in the nest body for total nitrogen (N) and exchangeable calcium (Ca), magnesium (Mg) and potassium (K), and in the mound wall for exchangeable K only. In contrast, available (Bray-1) phosphorus (P) content was found to be lower in both the mound wall and the nest body than in the adjacent topmost soil horizon. Consequently, the mounds formed by M. bellicosus contained 1.71?±?0.62?kg?ha^?1 of total N, 0.004?±?0.003?kg?ha^?1 of available P, 3.23?±?0.81?kg?ha^?1 of exchangeable Ca, 1.11?±?0.22?kg?ha^?1 of exchangeable Mg and 0.79?±?0.21?kg?ha^?1 of exchangeable K. However, with the exception of exchangeable K (1.2%), these nutrients amounted to less than 0.5% of those found in the topmost soil horizon. The soil nutrient turnover rate via M. bellicosus mounds was indeed limited, being estimated at 1.72?kg?ha^?1 for organic carbon (C), 0.15?kg?ha^?1 for total N, 0.0004?kg?ha^?1 for available P, 0.15?kg?ha^?1 for exchangeable Ca, 0.05?kg?ha^?1 for exchangeable Mg, and 0.06?kg?ha^?1 for exchangeable K per annum. These findings suggest that the mounds of M. bellicosus, while being enriched with some nutrients to create hot spots of soil nutrients in the vicinity of the mounds, are not a significant reservoir of soil nutrients and are therefore of minor importance for nutrient cycling at the ecosystem scale in the tropical savanna.     

Evaluation of Nutrient Release in Salt‐Saturated Soils

Abstract

The effects of irrigating with saline water on native soil fertility and nutrient relationships are not well understood. In a laboratory experiment, we determined the extent of indigenous nutrient [calcium (Ca), magnesium (Mg), potassium (K), manganese (Mn), and zinc (Zn)] release in salt-saturated soils. Soils were saturated with 0, 75, and 150 mmolc L^?1 sodium chloride (NaCl) solution and incubated for 1, 5, 10, and 15 days. The saturation extracts were analyzed for pH, ECe, and water‐soluble Ca, Mg, K, Mn, and Zn, and the remainder soil samples were analyzed for exchangeable forms of these elements. In a subexperiment, three soil types (masa, red‐yellow, and andosol) were saturated individually either with 100 mmolc L^?1 of NaCl, sodium nitrate (NaNO₃), or sodium sulfate (Na₂SO₄) salt. These salts were also compared for nutrient release. Soils treated with NaCl released higher amounts of water‐soluble than exchangeable nutrients. Except for Zn, the average concentrations of these nutrients in the soil solution increased significantly with time of incubation, but concentrations of the exchangeable forms varied inversely with time of incubation. The masa soil exhibited the highest concentrations of Ca and Mg, whereas K was highest in andosol. The extract from soils treated with NaCl contained greater amounts of soluble cations, whereas soils treated with Na₂SO₄ produced the lowest concentration of these elements irrespective of the type of soil used.     

Influence of potassium and magnesium fertilizer application on the yield and nutrient accumulation of maize genotypes under field conditions

The use of maize (Zea mays L.) genotypes that are able to utilize nutrients efficiently is an important strategy in the management of plant nutritional status; it is of particular importance with regard to potassium (K) and magnesium (Mg), due to their high requirement and influence on plant growth. The influence of K and Mg fertilizers on certain growth parameters of maize genotypes TM.815 and KL.72.AA, including length, seed in ear, seed weight growth, and nutrient concentration, was determined under field conditions over two successive years. The aim of the experiment was to study the effect of different rates of K and Mg fertilizers on maize genotype plant growth parameters, grain yield, and nutrient accumulation under field conditions.

A split plot design with three replicates was used and each block contained three treatments of 0, 100, and 200 kg ha^?1 of K₂O and 0, 10, and 20 kg ha^?1 of Mg; K₂SO₄ was used to supply K, and MgSO₄ was used for Mg.

Plants that responded to the K fertilizer had an increase in height, yield, and the concentration of K in the leaves and seeds. The addition of K fertilizer increased the concentration of nitrogen (N), iron (Fe), zinc (Zn), manganese (Mn), and K in the plant leaves and increased seed K concentration. Mg fertilizer increased the concentration of N, Fe, copper, and Mn in the leaves; however, it exerted no significant influence on K concentration. The KL.72.AA maize genotype had a higher mean plant height, number of seeds in ear, yield, and N, K, Fe, and Zn concentrations compared to the TM.815 maize genotype. In the experiment, the K fertilizer exerted a statistically significant effect on the leaf and seed K concentration; however, on a statistical basis, the Mg fertilizer did not affect the Mg concentration.     

Soil Nutrient Status and Leaf Nutrient Norms in Oil Palm (Elaeis Guineensis Jacq.) Plantations Grown in the West Coastal Area of India

Oil palm (Elaeis guineensis Jacq.) is a heavy feeder of nutrients and requires balanced and adequate supply of nutrients for optimum growth and yield. Information regarding soil nutrient status and leaf nutrient concentration is very much required for proper fertilizer application. Therefore, a survey was conducted for assessment of soil nutrient status and leaf nutrient concentration in 64 oil palm plantations in the state of Goa lying in the west coastal region of India. Soil pH, electrical conductivity (EC), organic carbon (OC), available potassium (K) (ammonium acetate-extractable K) (NH₄OAc-K), available phosphorus (P) (Bray’s-P), exchangeable calcium (Ca) (Exch. Ca) and magnesium (Mg) (Exch. Mg), available sulphur (S) (calcium chloride-extractable S) (CaCl₂-S), and hot water soluble boron (B) (HWB) in surface (0–20 cm depth) soil layers ranged from 4.25 to 6.77, 0.05 to 1.06 dS m^–1, 5.07 to 48.4 g kg^–1, 58.1 to 1167 mg kg^–1, 1.80 to 415 mg kg^–1, 200 to 2997 mg kg^–1, 36.0 to 744 mg kg^–1, 3.00 to 87.7 mg kg^–1 and 0.09 to 2.10 mg kg^–1, respectively. Diagnosis and Recommendation Integrated System (DRIS) norms were established for different nutrient expressions and were used to compute DRIS indices. As per DRIS indices, the order of requirement of nutrients in the region was found to be P > Mg > K > nitrogen (N) > B. Optimum leaf nutrient ranges as per DRIS norms varied from 1.64 to 2.79%, 0.36 to 0.52%, 0.37 to 0.75%, 0.89 to 1.97%, 0.35 to 0.63%, 0.89 to 1.50%, 3.10 to 13.9 mg kg^?1, 7.50 to 32.2 mg kg^?1, 35.0 to 91.1 mg kg^?1, 206 to 948 mg kg^?1, and 895 to 2075 mg kg^?1 for N, P, K, Ca, Mg, S, B, copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) respectively. On the basis of DRIS-derived sufficiency ranges, 14, 5, 11, 6, 6, 6, 8, 2, 3, 6, and 16% of leaf samples had less than optimum concentrations of N, P, K, Ca, Mg, S, B, Cu, Zn, Mn, and Fe respectively. The optimum ranges developed can be used as a guide for routine diagnostic and advisory purpose for balanced utilization of fertilizers.     

POTASSIUM-CONSTRAINED HIGH YIELDS IN IRRIGATED RICE

Nutritional constraints often restrict yields of field crops in farmers’ fields. Determination of cut-off yield would increase the understanding of yield-limiting nutrients. The present study aimed to determine minimum rice yield target of high-yielding subpopulation in farmers’ fields and to identify the most limiting nutrient in farmers’ fields. Popular high yielding rice was grown in 42 farmers’ fields with two treatments – farmers’ nutrient management plan (FP) and improved nutrient management plan (INM). Nutrient composition was determined from Y-leaf after 45– 50 days of transplanting. Yield cutoff value was determined from compositional nutrient diagnosis (CND) generic model. The CND generic model gave 6.90 Mg ha^?1 as minimum cutoff yield of the high-yield subpopulation. Potassium (K) was identified as the main yield limiting nutrient for rice in piedmont soils. Rice in farmers’ fields may require higher K fertilizer dose for better yield.     

Nutritional reference values for Opuntia ficus‐indica determined by means of the boundary‐line approach

Optimum concentrations and/or sufficiency ranges of nutrients are useful for a correct diagnosis and improvement of nutrient status of cultivated plants. To develop boundary‐line approach (BLA) standards for Opuntia ficus‐indica L., a database of N, P, K, Ca, and Mg concentrations in 1‐year‐old cladodes and cladodes fresh‐matter yield was used. The BLA optimum concentrations (associated with estimated maximum yield) for O. ficus‐indica were: N = 13.1 g kg^–1, P = 3.2 g kg^–1, K = 44.4 g kg^–1, Ca = 38.1 g kg^–1, and Mg = 17.3 g kg^–1. The BLA sufficiency ranges at 95% yield were 8.4–20.3 g kg^–1 for N, 2.4–4.2 g kg^–1 for P, 38.2–50.8 g kg^–1 K, 31.8–45.2 g kg^–1 for Ca, and 14.3–20.9 g kg^–1 for Mg. The BLA standards are comparable to those obtained in a previous study using compositional‐nutrient‐diagnosis (CND) approach.     

Balance and concentration of nitrogen and potassium affect growth and nutrient status in soilless cultivated lisianthus

Purpose: Nitrogen (N) / potassium (K) nutrient balance has been studied for some ornamental plants, however, available information is limited. Here we investigate the optimum N and K balance and concentration for lisianthus production in soilless medium.

Materials and methods: The effect of three N / K balances: 1.43, 2.14 and 4.29, prepared by varying the concentration of N and K, were evaluated in lisianthus grown in soilless medium (volcanic rock).

Results: Plants fertigated with a N / K balance of 2.14 exhibited enhanced height and stem dry weight when compared to plants fertigated with a balance of 4.29, and a higher flower buds count and total dry weight than those fertigated with a balance of 1.43 or 4.29. Plants fertigated with a balance of 2.14 exhibited increased dry weight when N was reduced from 15 to 9?meq?L^?1 and K from 7 to 4.2?meq?L^?1, suggesting that lisianthus does not require high levels of these nutrients. Although shoot N concentration was not correlated with N concentration in the nutrient solution or balance, increasing N in the shoot was associated with higher P and Mg in the plant tissues. In general, P, Ca, and Mg in plant tissues were unaffected by the external N / K balance, however, the internal P and Mg concentrations were positively correlated with shoot dry weight. Shoot K concentration significantly increased when the N / K balance decreased, which is related to the higher concentrations of external K when the balance decreased.

Conclusions: The optimum N / K balance for lisianthus was 2.14. However, there was a concentration effect, as fertigation with solutions containing a N / K balance of 2.14 and an N and K concentration of 9 and 4.2?meq?L^?1 respectively, resulted in plants with the greatest dry weight.     

Impact of planted hedgerow fallows on nutrient balances in a groundnut/maize/cassava intercrop

ABSTRACT

To assess if the nutrient supply through planted tree fallows meets crop nutrient uptake and export, N, P, K, Ca and Mg uptake and export by a groundnut/maize/cassava intercrop was compared with the nutrient uptake by three planted fallow systems (Senna spectabilis, Flemingia macrophylla, Dactyladenia barteri) and a no-tree control. Three cycles of two years fallow and one year cropping on Ultisol in southern Cameroon were studied. Fallows were slashed and burned. The fallow system had no consistent effect on nutrient uptake by individual crops. Crop nutrient uptake was most often highest in the S. spectabilis system. Nitrogen balances were generally negative due to N loss in the burn. Across three cropping cycles, the balance of fallow nutrient uptake versus total crop nutrient uptake was only in the S. spectabilis system positive for all nutrients. Nutrient export by all crops (mean of three years) was unaffected by fallow systems. The fallow nutrient uptake versus crop nutrient export balance was positive for all nutrients and systems. Planted fallows appear capable of acquiring sufficient nutrient stocks during fallow phases, covering the crops’ demand. Fallow N and K uptake and crop export declined with every fallow/cropping cycle.     

Input and output of major nutrients under monocropping sisal in Tanzania

A semiquantitative nutrient balance is presented for a field monocropped with sisal on Ferralsols in Tanzania. Input of nutrients included wet deposition, non-symbiotic nitrogen fixation and nutrients added with planting material. Nutrient output consisted of the harvested product. The average annual shortfall between 1966 to 1990 was 12 kg N ha⁻¹, 2·8 kg P ha⁻¹, 38 kg K ha⁻¹, 44 kg Ca ha⁻¹ and 19 kg Mg ha⁻¹. The nutrient balance was compared to changes in topsoil (0–20 cm) nutrient contents of the sisal field during the same period. Average annual decrease in soil nutrient contents was: 104 kg N ha⁻¹, 1·8 kg P ha⁻¹, 11 kg K ha⁻¹, 29 kg Ca ha⁻¹ and 10 kg Mg ha⁻¹. Much more nitrogen was lost from the topsoil than can be explained by the nutrient balance, indicating significant losses. Changes in soil phosphorus content are almost explained by the nutrient balance. More exchangeable cations were removed with the yield than were lost from the topsoil, which may imply that cations are extracted from the subsoil. Both the nutrient balance and the changes in soil nutrient contents showed that monocropping sisal is mining nutrients. © 1997 John Wiley & Sons, Ltd.     

长期定位试验中氮肥与磷肥有机肥联合施用通过刺激根的生长增加玉米产量和养分吸收

Imbalanced application of nitrogen (N) and phosphorus (P) fertilizers can result in reduced crop yield, low nutrient use efficiency, and high loss of nutrients and soil nitrate nitrogen (NO₃^--N) accumulation decreases when N is applied with P and/or manure; however, the effect of applications of N with P and/or manure on root growth and distribution in the soil profile is not fully understood. The aim of this study was to investigate the combined effects of different N and P fertilizer application rates with or without manure on maize (Zea mays L.) yield, N uptake, root growth, apparent N surplus, Olsen-P concentration, and mineral N (Nmin) accumulation in a fluvo-aquic calcareous soil from a long-term (28-year) experiment. The experiment comprised twelve combinations of chemical N and P fertilizers, either with or without chicken manure, as treatments in four replicates. The yield of maize grain was 82% higher, the N uptake 100% higher, and the Nmin accumulation 39% lower in the treatments with combined N and P in comparison to N fertilizer only. The maize root length density in the 30--60 cm layer was three times greater in the treatments with N and P fertilizers than with N fertilizer only. Manure addition increased maize yield by 50% and N uptake by 43%, and reduced Nmin (mostly NO₃^--N) accumulation in the soil by 46%. The long-term application of manure and P fertilizer resulted in significant increases in soil Olsen-P concentration when no N fertilizer was applied. Manure application reduced the apparent N surplus for all treatments. These results suggest that combined N and P fertilizer applications could enhance maize grain yield and nutrient uptake via stimulating root growth, leading to reduced accumulation of potentially leachable NO₃^--N in soil, and manure application was a practical way to improve degraded soils in China and the rest of the world.     

Effect of 22-Year-L​ong Conjunctive Use of Organic and Chemical Sources of Nutrients on Crop Yield,Soil Properties,and Nutrient Balance in Post-Monsoon Sorghum (Sorghum bicolor L.) in Peninsular Vertisols of India

A long-term field experiment was conducted in Vertisols of Solapur (Maharashtra, India) to assess the effect of the integrated use of nutrients on yield, soil properties, and nutrient balance in post-monsoon sorghum. The highest crop yield (1.19 Mg ha^?1) and available nutrients (308, 14.9, and 814 kg ha^?1 nitrogen (N), phosphorus (P), and potassium (K), respectively) were recorded in the treatment of 25 kg N sorghum crop residue (CR) + 25 kg N Leucaena clippings (LCs), 25 kg N (CR) + 25 kg N (urea), 25 kg N farmyard manure + 25 kg N (urea), and 25 kg N (CR) + 25 kg N (LC), respectively. Most of the nutrients were depleted except K and Ca. The response ratio for N (16 kg kg^?1) and partial factor productivity (33 kg kg^?1) were considerably higher in the 25 kg N (CR) + 25 kg N (LC) treatment. Conjunctive use of organic ?and chemical fertilizers helped in reducing the nutrient losses and improved their use efficiency and yield sustainability.