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1.
Abstract

A cotton (Gossypium hirsutum)–peanut (Arachis hypogaea L.) rotation is widely practiced in the southern coastal plain following the reemergence of cotton as a major crop in the 1990s. Very few plant nutrition studies have been conducted in the coastal plain (CP) with modern cotton varieties and none with the cotton–peanut rotation. Experiments with varying rates of nitrogen (N), phosphorus (P), and potassium (K) were conducted to determine if the recommendations from soil tests provide adequate nutrition for maximizing profit when yield goals are Georgia state averages, due to other conditions. From 1996 through 1998, N, P, and K experiments were conducted in cotton crops, and P and K experiments were conducted in peanut crops on Tifton loamy sand. Initial Mehlich‐1 P was 2 to 3 mg/kg (“low”) and Mehlich‐1 K was 50 to 64 mg/kg (“medium” for cotton and “high” for peanut). Each crop was grown each year. State average yields of cotton and peanuts were produced. There was no response in cotton yield to N rates from 34 to 136 kg N/ha. Lack of response may have been due to the fact that the field had not been in production for several years prior to 1996 and there was ample soil mineral N. In 1997 and 1998, residual N provided by N fixation by the previous peanut crop appeared to be sufficient. Maximum profit from P fertilization in cotton was attained at 50 kg P/ha, the recommendation from the soil test. However, a University of Georgia Cooperative Extension Service recommendation to double the P rate for new land with a “low” Mehlich‐1 P soil test was not validated. Cotton yield did not respond to K fertilization even though an application of 55 kg K/ha/year was recommended from the soil test. Peanut yield and grade did not respond to either P or K fertilization. The recommendation from the soil test was 40 kg P/ha/year and no K. Estimates of P removal were 11 kg/ha for cotton and 8 mg/ha for peanut crops. Estimates of K removal were 25 kg/ha for cotton and 22 kg/ha for peanut crops. Over 3 years, soil P was not depleted, but soil K was depleted. Approximately 12 kg P/ha were required to raise soil test P 1 mg/kg and 18 kg K/ha were required to raise soil test K 1 mg/kg (49 lb. P2O5 to increase the P test 1 lb./acre, 38 lb. K2O to raise the K test 1 lb./acre). Additional studies are needed, but the current studies suggest that revisions in recommendations are needed for both cotton and peanut crops.  相似文献   

2.
Acid sulfate soils (ASS) are characterized by low pH, aluminum (Al), and iron (Fe) toxicity and are typically deficient in phosphate (PO4). The application of phosphorus (P) fertilizer could help reduce the level of exchangeable Al and Fe, thereby improving the rice growth and yield. Five levels of P (0, 20, 40, 60 and 80 kg phosphorus pentoxide (P2O5)/ha) were tested with rice varieties MTL560 in the wet season and MTL480 in the dry season. The optimum rate of P was 60 kg P2O5/ha for rice in the dry season and 80 kg P2O5/ha in the wet season. Soil testing showed at the start of the season that there was sufficient P in the soil. At the end of the season there was a reduction in soil Al and Fe in plots that had P rates above 40 kg P2O5/ha. It is therefore likely that P application reduced Al and Fe toxicity through precipitation and formation of Al-P and Fe-P compounds, which boasted yield, rather amending a soil P deficiency.  相似文献   

3.
Optimization of phosphorus (P) fertilization is important for balancing soil fertility especially in vertisol to support economic crop production. The objective of the study was to determine the impact of P fertilization (1998 to 2014) on crop yield and nutrient uptake, and soil fertility under continuous annually tilled corn (Zea mays L.)-wheat (Triticum aestivum L.) system in semi-arid Mediterranean conditions. The study was conducted on Arik clay (isohyperthermic, fine clay Typic Haploxerert) using randomized complete block design with four replications for each treatment at the research farm of the Dept. of Soil Science and Plant Nutrition, Çukurova University, Adana, Turkey. P fertilizer at 0, 50, 100, 200 kg P2O5 ha?1 as triple superphosphate (TSP), respectively was applied a week before planting corn. Results showed that increasing P fertilization rates significantly decreased the number of mycorrhizal spores associated with corn roots. Similarly, a 10% decrease in corn root mycorrhizal colonization was observed with 200 kg P2O5 ha?1 fertilization. In the control treatment, corn yield was 4.3 Mg ha?1 as compared to 5.6, 5.7 and 6.1 Mg ha?1 in 50, 100 and 200 kg of P2O5/ha, respectively. The relationship between P fertilization and relative yield showed that more than 95% of the corn yield was produced when P applied at 100 kg P2O5 ha?1. While P fertilization significantly increased the leaf N, P, and K contents but decreased the leaf Zn, Fe and Mn contents, as compared with the control. However, P fertilization did not consistently affect the grain N and P contents. Both physiological efficiency- and agronomic efficiency of P fertilization have shown a significant non-linear increase than that of the control. Total organic C (TOC) and total N (TN) concentrations were more than 34 and 26% higher in 100 and 200 kg P2O5 ha?1rates as compared with the control. Likewise, available P (AP), manganese (Mn) and zinc (Zn) concentrations increased with an increase in P fertilization rates. The AP, Mn and Zn contents significantly stratified by P fertilization. Our results suggested that 100 kg P2O5 ha?1 is optimum to sustain Vertisol fertility for supporting economic corn production in the Mediterranean climates of Turkey.  相似文献   

4.
In a long‐term maize–wheat rotation at the Punjab Agricultural University, Ludhiana, India (subtropical climate), the effects of nitrogen (N), phosphorus (P), and potassium (K) addition on soil fertility and forms of inorganic P and K in the plow layer of an alkaline sandy loam soil were measured after 11 and 22 years of cropping. The treatments comprised four rates of N (0, 60, 120, and 180 kg N ha?1) as urea, three rates of P (0, 17.5, and 35 kg P ha?1) as single superphosphate, and two rates of K (0 and 33 kg K ha?1) as muriate of potash. The treatments selected for the present study were N0P0K0, N120P0K0, N120P17.5K0, N120P35K0, N120P17.5K33, and N120P35K33. A significant year × treatment interaction in decreasing available N [alkaline potassium permanganate (KMnO4)–oxidizable N) status of soils was found in all the treatments. Available P (Olsen P) in the control plot decreased over time whereas in plots with added P, available P increased significantly after years 11 and 22, with the greatest increase in the N120P17.5Ko treatment. Compared to the initial values, continuous P fertilization resulted in greater total P and chloride P concentrations after 11 and 22 years. Although sodium hydroxide (NaOH) P and sulfuric acid (H2SO4) P increased in P‐treated plots from the start of the trial to year 11, they decreased from year 11 to year 22. Among these inorganic P forms, chloride P was significantly positively correlated with P uptake (r = 0.811*). When only N and P were applied, available K [ammonium acetate (NH4OAc)–extractable K] significantly decreased over time. In plots without K addition, water‐soluble and exchangeable K decreased from their initial status. Compared to year 11, water‐soluble K increased, whereas exchangeable K decreased after year 22 in plots receiving no K fertilizer. Compared with NPK treatments, a significant decrease of total K in NP treatment plots suggests the release and uptake of nonexchangeable K. Water‐soluble K and exchangeable K were not correlated with K uptake. These results suggest that long‐term application of P fertilizers resulted in the accumulation of P in the soil, which could have resulted in saturation of P binding sites. Of the soil inorganic P fractions, only chloride P appears to be a good indicator of plant‐available P. The gradual loss in native soil K and release of nonexchangeable K indicates the need for adding K fertilizer to maintain soil fertility.  相似文献   

5.
Application of manure on the basis of crop nitrogen (N) need increases the level of soil phosphorus (P), which is concern for deterioration of surface water quality. Soil samples were collected from a long-term field study to investigate the impact of crop N need–based manure application on soil P fractions and P adsorption and release kinetics. The field experiment was initiated in 1990. The soil was moderately well-drained Kennebec (fine silty, mixed, mesic Cumulic Hapludolls). No-tillage (NT) and conventional-tillage (CT) treatments were established in main plots, and subplots had five N treatments, including a control, and annual application of 84 or 168 kg N ha?1 applied as ammonium nitrate (NH4NO3) or beef (Bos taurus) manure. Manure at the high N application rate had significantly greater Bray 1 P under NT than under CT at 0- to 5-cm soil depth. Nitrogen fertilizer treatments were not significantly different than the control for Bray 1 P. Continuous application of manure at the high N rate significantly increased all Hedley P fractions; however, the major increase was observed in high bioavailable P pools [iron oxide (FeO) P and sodium bicarbonate (NaHCO3) Pi] and hydrochloric acid (HCl) P fractions. Soil organic P (Po) pools, including both labile (NaHCO3-Po) and resistant [sodium hydroxide (NaOH) Po], were increased by application of N from any source, suggesting biomass production and return of residue to soil surface was the responsible factor. Continuous application of manure based on N need also significantly increased FeO-P, NaHCO3-Pi, and HCl-P fractions at lower soil depths (5–15 and 15–30 cm). Results from the P-adsorption study suggest that ability of soil to adsorb additional P was decreased by manure application and that EPC0 was increased. Maximum desorbable P was observed for manure treatments under NT, although the release constant k (h?1) was significantly less than with fertilizer N treatments.  相似文献   

6.
The nature of organic phosphorus (Po) in animal waste and in soil is important from both plant nutrition and environmental perspectives. The objectives of this study were (1) to monitor the nature of Po in different animal wastes and biosolids using solution state 31P NMR spectroscopy and (2) to understand the nature of Po as affected by crop P removal in soil amended with different animal wastes and biosolids under greenhouse conditions. Two types of stockpiled cattle (Bos taurus) manure (CM1 and CM2), solid turkey (Meleagris gallopava) litter (TL), solid hog (Sus scrofa) manure (HM), and aerobically digested biosolids (SS) were used. Two kg of Wabash silt loam soil was amended with 0 or 150 mg P kg?1 from the P sources. Seven harvests of corn (Zea mays L.) were collected, each 35 days after sowing. Organic P was extracted with 0.4 M NaOH from soil samples collected before cropping and after the seventh harvest, as well as from each P source. 31P NMR analysis suggested that sugar phosphomonoester was present in all P sources and was the dominant constituent of both CM1 and CM2. Phosphomonoester was detected in large amounts in TL, HM, and SS. Prior to crop P removal, the application of all P sources caused the relative content of sugar phosphomonoester to be greater than the control. Crop P removal resulted in reductions in the relative content of sugar phosphodiesters and phosphodiester in CM1‐ and CM2‐amended soils, respectively. Phosphomonoester was also decreased in TL‐, HM‐, and SS‐amended soils in response to cropping.  相似文献   

7.
Irrigated rice is less prone generally to phosphorus (P) deficiency than rainfed rice because redox reactions release P upon soil flooding. It is not known whether that is also true in highly weathered soils of Madagascar where the combination of high soil Fe and low P input may impede significant release of P. Soils and flag leaf samples were collected in 2010 in 38 irrigated rice and 46 rainfed rice fields belonging to private farmers. A critical flag leaf P content was derived from a P‐dosed pot trial study with three soils, and the results suggested 2.4 g P/kg as the critical value. Average flag leaf P was significantly larger in irrigated than in rainfed rice (2.2 compared with 1.7 g P/kg), and flag leaf P was below the critical value in 76% of irrigated rice fields while this fraction was 100% in rainfed rice. Nitrogen and K deficiencies were less prevalent. Flag leaf P increased with increasing soil pH and soil pH explained partially differences in leaf P between irrigated and rainfed rice. Flag leaf P was unrelated to soil organic matter, but increased with oxalate‐extractable soil P (Po). Multiple regression analysis revealed greater leaf P at equal soil Po and equal pH in irrigated compared with rainfed rice. Grain yield estimates (1‐m2 squares) increased with flag leaf P but not with leaf N and K. In a regression model, about 42 % of the yield variance was explained with soil Po and a rice‐growing system. The survey suggests that P is the main limiting nutrient for rice, and that soil P bioavailability is larger for irrigated than for rainfed rice in weathered soils of Madagascar.  相似文献   

8.
This study investigated phosphorus (P) dynamics and kinetics in calcareous soil under inorganic, organic, and integrated (inorganic+organic) fertilizer systems during two growing seasons of maize in two soil depths (0–0.15 and 0.15–0.30 m). A field experiment was conducted with 150, 300, and 400 kg ha?1 triple superphosphate (TSP), 7.5 and 15.0 ton ha?1 (on dry matter basis) farmyard manure (FYM), and integrated systems. In order to analyze Olsen P, soil samples were collected in 30-day-intervals after planting. The results showed that at the end of the two growing seasons of maize, the lowest magnitudes of Olsen P0–0.15 m were 6.0, 6.8, 7.4, and 7.6 mg kg?1 for the control, 7.5 FYM, 15 FYM, and 150 TSP, respectively. The highest magnitudes of Olsen P0–0.15 m were 12.4, 11.5, 11.4, and 11.1 mg kg?1 for 300 TSP+15 FYM, 400 TSP+7.5 FYM, 400 TSP+15 FYM, and 300 TSP+7.5 FYM, respectively. The same trends were observed for Olsen P0.15–0.30 m. Heterogeneous diffusion model demonstrated that Elovich equation could best describe the experimental data (mean; R2 = 0.98, SE = 0.29). The highest P supply rates (PSR) were 4.73, 3.91, and 3.86 mg kg?1day?1 (days after application) for 400 TSP, 400 TSP+15 FYM, and 300 TSP, respectively. The models of P supply capacity of soil could estimate P supply of soil under different fertilizer systems (R2 = 0.84–0.95). The present study improved the understanding of the capacity and rate of P supply by considering P uptake by grain maize. Fertilizer recommendations depend on the accessibility of fertilizer types suggested to help choose the best fertilizer systems.  相似文献   

9.
With the emphasis on sustainable agriculture, attention has been increasingly turning to recycling of crop residues as a component of fertility management strategies for tropical soils. We assessed the effects of soybean residue (SR) and wheat residue (WR) applied either alone or in combination with fertilizer P (FP) on dynamics of labile P, distribution of P fractions, and P sorption in a semiarid tropical Alfisol by conducting a 16 w long incubation experiment. The amount of P added through crop residues, FP or their combinations was kept constant at 10 mg P (kg soil)–1. Addition of SR or WR resulted in net increase of labile inorganic (Pi) and organic P (Po) and microbial P throughout the incubation period, except that the WR decreased labile Pi during first 2 w due to Pi immobilization. The P immobilization associated with WR addition was, however, offset when fertilizer P was combined with WR. Generally, the increases in labile‐P fractions were larger with the SR and SR+FP than with the WR and WR+FP. The sequential fractionation of soil P at the end of 16 w indicated that a major part of added fertilizer P transformed into moderately labile and stable P fractions as evident from the increased NaOH‐Pi and HCl‐P in the FP treatment. In contrast, the addition of SR and WR alone or in combination with FP favored a build‐up in NaHCO3‐Pi and ‐Po and NaOH‐Po fractions while causing a decrease in NaOH‐Pi and HCl‐P fractions. The addition of these crop residues also effectively decreased the P‐sorption capacity and hence reduced the standard P requirement of the soil (i.e., the amount of P required to maintain optimum solution P concentration of 0.2 mg P l–1) by 24%–43%. Results of the study, thus, imply that soybean and wheat crop residues have the potential to improve P fertility of Alfisols by decreasing P‐sorption capacity and by redistributing soil P in favor of labile‐P fractions and promoting accretion of organic P.  相似文献   

10.
Most previous studies have limited the assessments of soil phosphorus (P) status within the plow layer. This study was to assess the impacts of crop sequences and nutrient sources on P status of a Labarre silty clay (Humic Cryaquept) profile in a frigid continental climate. Soil of the 0- to 15-, 15- to 30-, 30- to 60-, and 60- to 90-cm layers was sampled from a split-plot experiment comprising a barley (Hordeum vulgare L.) monoculture and a 3-year barley-forage rotation as main plots, and receiving mineral fertilizers (MIN) or liquid dairy manure (LDM) as subplots. A modified Hedley sequential fractionation was used to characterize soil P status. Labile P pools were more affected than stable ones by the investigated treatments. After 10 years, the MIN resulted in larger resin-P and NaHCO3-Pi, and lower NaHCO3-Po and NaOH-Po pools than the LDM in the top 30 cm of soil. The rotation resulted in larger labile Pi and Po pools than the monoculture in the 30- to 60-cm layer. The rotation associated with LDM produced the largest total labile P pool, whereas the LDM resulted in an about 20% higher degree of soil P saturation as expressed by the Pox/(Feox + Alox) molar ratio than the MIN in the 0- to 30-cm layer. Our observations stressed that the impacts of crop sequences and nutrient sources on soil labile P extended deeper into the profile than the disturbance caused by primary tillage.  相似文献   

11.
An 8-year field study documented the impact of tillage, crop rotations, and crop residue management on agronomic and soil parameters at Brookings, South Dakota. The greatest annual proportion of above-ground biomass phosphorus (P) removed was from the grain (78–87% of total) although crop residue removed some P as well. Greater above-ground total biomass P (grain P + crop residue P) was removed from corn than from soybean and spring wheat crops mainly due to the greater corn grain biomass harvested. Cumulative above-ground biomass P removal was greatest for the corn-soybean rotation (214 kg P ha?1), while it was lowest for the soybean-wheat rotation (157 kg P ha?1). Tillage treatments within crop rotation or residue management treatments did not influence annual or cumulative P removal rates. Olsen extractable soil orthophosphate-P levels declined consistently through time from a mean of 40 µg g?1 (2004) to 26 µg g?1 (2011). Biomass P removal was calculated to be 15.7 ha?1 yr?1 to decrease Olsen extractable soil orthophosphate-P levels by 1 µg g?1 yr?1 over 8 years of the study.  相似文献   

12.
Abstract

The variability in corn yield responses to applications of Zn fertilizer appears to be associated with several complex soil and climatic factors that affect the availability of endogenous soil Zn to the crop under specific conditions. Among the soil chemical properties that influence availability of endogenous Zn are soil pH, organic matter content, and extractable P. Over a period of several years, soil and plant analysis data were collected from 54 field experiments, field trials, and diagnostic visits to producer's fields. These data were subjected to multiple regression analysis, resulting in an equation: Znleaf = 37.14 + 1.513 Znst ‐4.04 pHst ‐ 1.791 ln(Pst/100) where Znst, pHst, and Pst were 0.1N HC1 extractable soil Zn (kg/ha), 1:1 soil‐water pH, and Bray's 1 extractable soil P (kg/ha), respectively. These factors accounted for 67% of variation in leaf Zn, which was a large portion of the variability in Znleaf considering that climatic conditions, management levels, and varietal differences were uncontrolled in most instances. Using the previously published critical level in the leaf opposite and below the ear as 17 μg Zn/g, these data can be used to set required soil test levels of Zn at different levels of extractable P and soil pH. Inadequate levels of extractable Zn would range from 2.5 (at pH 6.0, P = 70 kg/ha) to, 9.5 kg/ha (at pH 7.5, P = 420 kg/ha).  相似文献   

13.
Phosphorus (P) is a limited resource, and its efficient use is a main task in sustainable agriculture. In a 6‐year field experiment on a loamy‐sand soil poor in P, the effects of organic, inorganic, and combined organic‐inorganic fertilization on crop yield, P uptake into grain, and soil properties (organic matter [OM] content, pH, water‐extractable P [Pw], double lactate–extractable P [Pdl], oxalate‐extractable P [Pox], P‐sorption capacity [PSC], and degree of P saturation [DPS]) were investigated for the maritime climate in northeast Germany. Nine treatments were compared: a control treatment without fertilizer application, two organic fertilizers (cattle manure [CM] and biowaste compost [BC]; applied at a rate of 30 t ha–1 in autumn 1998 and 2001), application of triple‐superphosphate (TSP; applied once a year either in autumn or in spring to evaluate the effects of application date), and combinations of organic and inorganic fertilizations. Several winter and spring crops (oilseed rape, barley, wheat) were cultivated according to good agricultural practice. The 6 year–average yield and P uptake were significantly higher for fertilized plots than for nonfertilized plots. Although the combination of organic × inorganic fertilizers resulted in higher soil P contents, significant yield increases were only found when organic fertilization was combined with TSP in spring. Small effects of P supply on yield in some years indicate that plant‐available soil P (despite of low Pdl values) was sufficient for crop growth. Phosphorus supply affected soil Pdl and Pw more than the parameters measured in the oxalate extract (Pox, PSC, DPS). In general, periodically applied cattle manure and biowaste compost had the same effect on yield, P uptake, and soil P status as annually applied soluble mineral P.  相似文献   

14.
A field experiment was conducted for eight years at ICAR-Indian Institute of Wheat and Barley Research, Karnal, Haryana, India to study the skipping effect of P application on productivity, profitability and sustainability of rice-wheat cropping system. Rice yield and biomass were 8.35% and 6.6% higher where cowpea was grown after wheat compared to rice-vegetable pea-wheat crop sequence, respectively. Phosphorus application to rice or wheat or both crops exhibited at par rice grain yield, biomass, harvest index. Phosphorus application to both crops or only in rice crop produced maximum and significantly higher wheat yield (4.62 t ha?1) as compared to P application only to wheat (4.48 t ha?1). Eight years growing of green gram, cowpea and vegetable pea increased the organic carbon content 42.89, 16.38 and 4.57 %, respectively compared to the initial level. Skipping of P to either crop, by considering 13.5 million ha rice-wheat area, will save approximately Rs 40,500 million (Rs = Indian rupee) or US $ 623 million ($ = Rs 65) per year. Air pollution may be checked, due to saving on diesel in transportation of P fertilizer, to the tune of 60,383 tonnes of CO2 per year by reducing emission of one of important global warming gas.  相似文献   

15.
Phosphorus losses from arable land in England   总被引：7，自引：0，他引：7  
Abstract. Concentrations and annual loadings of molyhdate reactive P (MRP) and total (including particulate) P (TP) are reported from field drainage, catchment and erosion experiments in England. Annual losses through field drains and in catchment runoff were 0.037-0.74 kg MRP/ha and 0.37-2.64 kg TP/ha, but those in surface runoff from experimental plots measuring erosion were generally much greater (often > 3 kg MRP/ha and up to 32 kg TP/ha in a wet year). Amounts of TP in drainflow and catchment runoff depended upon factors influencing soil dispersibility, such as particle size distribution and calcium carbonate content. The results to date suggest that P losses in surface runoff and erosion from arable fields to water are best limited by: (a) maximizing crop cover, using minimal cultivation practices and where possible planting crop rows across rather than up and down the slope, (b) avoiding cultivation practices that result in dispersion of soil particles, and (c) avoiding application of P fertilizer to wet soils when rainfall is likely soon after application. Consideration should he given to maintaining field drains below peak efficiency to reduce subsurface P losses.  相似文献   

16.
A major challenge in sustainable crop management is to ensure adequate P supply for crops, while minimizing losses of P that could negatively impact water quality. The objective of the present study was to investigate the effects of long‐term applications of different levels of mineral fertilizers and farmyard manure on (1) the availability of P, (2) the relationship between soil C, N, and P, and (3) the distribution of inorganic and organic P in size fractions obtained by wet sieving. Soil samples were taken from the top 20 cm of a long‐term (29 y) fertilization trial on a sandy Cambisol near Darmstadt, SW Germany. Plant‐available P, determined with the CAL method, was little affected by fertilization treatment (p < 0.05) and was low to optimal. The concentration of inorganic and organic P extracted with a NaOH‐EDTA solution (PNaOH‐EDTA) averaged about 350 mg (kg dry soil)–1, with 42% being in the organic form (Po). Manure application tended to increase soil C, N, and Po concentrations by 8%, 9%, and 5.6%, respectively. Across all treatments, the C : N : Po ratio was 100 : 9.5 : 2 and was not significantly affected by the fertilization treatments. Aggregate formation was weak due to the low clay and organic‐matter content of the soil, and the fractions > 53 μm consisted predominantly of sand grains. The different fertilization treatments had little effect on the distribution of size fractions and their C, N, and P contents. In the fractions > 53 μm, PNaOH‐EDTA ranged between 200 and 300 mg kg–1, while it reached 1260 mg kg–1 in the fraction < 53 μm. Less than one third of PNaOH‐EDTA was present as Po in the fractions > 53 μm, while Po accounted for 70% of PNaOH‐EDTA in the smallest fraction (< 53 μm). Therefore, 16% and 28% of PNaOH‐EDTA and Po, respectively, were associated with the smallest fraction, even though this fraction accounted for < 5% of the soil mass. Therefore, runoff may cause higher P losses than the soil P content suggests in this sandy soil with a weak aggregate formation. Overall, the results indicate that manure and mineral fertilizer had similar effects on soil P fractions.  相似文献   

17.
The management of crop residues coupled with external nutrient inputs is important for improving and conserving soil fertility and productivity. We assessed the long-term effects of three wheat residue management options (RMO) (residue burning, incorporation, and surface retention) in combination with three supplementary nutrient inputs (SNI) [control, fertilizer, and farmyard manure (FYM)] on phosphorus (P) fractions and adsorption behavior of a Vertisol under soybean–wheat system. Wheat residue incorporation and retention improved the labile inorganic P [sodium bicarbonate (NaHCO3-Pi)] by 3.2 and 5.0 mg kg?1 and the labile organic P (NaHCO3-Po) by 2.4 and 4.2 mg kg?1, respectively, as compared to residue burning. The soils under residue incorporation and retention had 38 and 26% more moderately labile organic P [sodium hydroxide (NaOH-Po)], respectively, than the soil under residue burning. The SNI either as fertilizer or FYM further enhanced NaHCO3-Pi, NaHCO3-Po, and NaOH-Po. In contrast, less labile P fractions [hydrochloric acid (HCl)-P and residual-P] remained unaffected by RMO and SNI treatments. Residue retention or incorporation decreased P adsorption over the residue burning for all the three nutrient inputs. The P-adsorption data fitted well to the Langmuir equation (R2 ranged from 0.970 to 0.994). The P-adsorption maximum (b), bonding energy constant (k), differential P-buffering capacity (DPBC), and standard P requirement (SPR) were lower with residue incorporation or surface retention than with residue burning. The SPR followed the order residue burning > incorporation > retention for RMOs and control > fertilizer > FYM for SNI treatments. The NaHCO3-Pi, NaHCO3-P0, and NaOH-Po had negative correlation with P-adsorption parameters and showed positive correlation with soybean P uptake. Wheat residue incorporation or retention plus FYM could be an effective strategy for enhancing the P fertility of Vertisols under a soybean–wheat system.  相似文献   

18.
Abstract

Elevated soil phosphorus (P) content is common in the central coastal valleys of California, the result of decades of the intensive vegetable production. Undesirably high P concentration in surface water in this region stimulated interest in evaluating techniques to rank the potential for soil P loss to the environment. Phosphorus availability of 25 representative soils from fields in vegetable rotations were evaluated by the following techniques: bicarbonate‐extractable P (Pbc)–calcium chloride, extractable P (Pcc), P extractable by iron‐impregnated paper (PFe), P extractable by anion exchange resin (Pae), and the degree of P saturation (Psat). A column study was conducted in which these soils were evaluated for soluble P concentration in runoff and leachate from two simulated irrigation events. There were strong correlations among all measures of soil P availability (r=0.66–0.90). Runoff soluble P was most strongly correlated with Pcc, Pae, and Pbc (r=0.98, 0.93, and 0.91, or 0.98, 0.90, and 0.85 in the first and second irrigation, respectively). The relationship of runoff soluble P to Pbc, Pae, and Pcc was characterized by a change point; runoff soluble P from soils <50 mg kg?1 Pbc was minimal, whereas at higher Pbc runoff P reached levels of environmental concern. Leachate soluble P was also correlated with Pcc, Pae, and Pbc (r=0.84–0.99). Across soils, leachate soluble P averaged 1.4 mg L?1, compared to 0.11 mg L?1 for runoff P. We conclude that Pcc, Pae, and Pbc are useful tests to rank the potential for P loss in irrigation runoff or drainage. Given the relative complexity of the Pae technique, Pbc and Pcc appear to be the most practical soil tests for this purpose.  相似文献   

19.
Repeated application of phosphorus (P) as superphosphate either alone or in conjunction with cattle manure and fertilizer N may affect the P balance and the forms and distribution of P in soil. During 7 years, we monitored 0.5 M NaHCO3 extractable P (Olsen‐P) and determined the changes in soil inorganic P (Pi) and organic P (Po) caused by a yearly dose of 52 kg P ha—1 as superphosphate and different levels of cattle manure and fertilizer N application in a soybean‐wheat system on Vertisol. In general, the contents of Olsen‐P increased with conjunctive use of cattle manure. However, increasing rate of fertilizer nitrogen (N) reduced the Olsen‐P due to larger P exploitation by crops. The average amount of fertilizer P required to increase Olsen‐P by 1 mg kg—1 was 10.5 kg ha—1 without manure and application of 8 t manure reduced it to 8.3 kg ha—1. Fertilizer P in excess of crop removal accumulated in labile (NaHCO3‐Pi and Po) and moderately labile (NaOH‐Pi and Po) fractions linearly and manure application enhanced accumulation of Po. The P recovered as sum of different fractions varied from 91.5 to 98.7% of total P (acid digested, Pt). Excess fertilizer P application in presence of manure led to increased levels of Olsen‐P in both topsoil and subsoil. In accordance, the recovery of Pt from the 0—15 cm layer was slightly less than the theoretical P (P added + change in soil P — P removed by crops) confirming that some of the topsoil P may have migrated to the subsoil. The P fractions were significantly correlated with apparent P balance and acted as sink for fertilizer P.  相似文献   

20.
Abstract

Disposing poultry manure from broiler and layer flocks by its incorporation into the soil was evaluated on greenhouse lettuce (Lactuca sativa L. cv. Paris Island cos). Floor litter that contains the manure mixed with sawdust and wood shaving, was 8 weeks old from broilers and one year old from layers. Broiler manure had 19% moisture and 5.5% N, while layer manure had 22% moisture and 3.7% N. Application of 27.5 ton/ha broiler manure and 18 ton/ha layer manure, on wet basis, gave comparable yield of lettuce as did an application of 100 kg N/ha from NH4NO3 in 2 split applications, and an unfertilized treatment. The manure was effective for lettuce growth 10 months after its incorporation in the soil. The highest yield was in manure treated plots, however, the lack of significant response in yield is due to the sufficient levels of soil NO3‐N and available P. There was no effect on soil EC, pH, and available P due to the treatments; however, soil NO3‐N was significantly increased under all fertilized treatments. Leaf concentration of PO4‐P was not affected by the treatments, but NO3‐N was significantly increased under all fertilized treatments. It may be concluded that broiler and layer poultry manure when disposed of by soil incorporation, are equally effective as a fertilizer for a leafy crop such as lettuce.  相似文献   

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