Rates Of Mineral Nitrogen Fertilizer Research Articles

Response of Some Soybean Genotypes to Insect Infestation under Three Mineral Nitrogen Fertilizer Rates

Background: A two-year study was conducted at Giza Agricultural Research Station, Agricultural Research Center (ARC), Egypt, to evaluate the productivity of six genotypes of soybeans under three mineral nitrogen (N) fertilizer rates, as well as their resistance to insects, in comparison to four check varieties. Methods: The study took place during the 2021 and 2022 summer seasons. The treatments included three mineral N fertilizer rates (N1=67% of N fertilizer rate “71.4 kg N/ha”, N2=33% of N fertilizer rate “35.7 kg N/ha” with seed inoculation by Bradyrhizobium japonicum and N3=100% of N fertilizer rate of the recommended rate “107.1 kg N/ha”) and ten soybean genotypes (H4L4, H6L198, H18L54, H29L115, H129, Misr 10, along with Dr101 and Giza 111 “resistant” and Giza 82 and Crawford “susceptible”). The experiment used a split plot design with three replications. The main plots were assigned the mineral N fertilizer rates, while the subplots, were assigned the soybean genotypes. Result: Fewer cotton leaf worms, whiteflies and leaf miners were found after applying N1 or N2. In the 6th week from sowing, Misr 10 and Dr 101 had fewer cotton leaf worms and whiteflies. In contrast, throughout the 7th, 8th and 9th weeks from sowing, Misr 10 and H6L198 had fewer cotton leaf worms. Misr 10 had fewer leaf miners in every week and fewer whiteflies in the 7th, 8th and 9th weeks from sowing. In the 6th week of the first season, Misr 10, Dr101, H18L54 and Giza 111 that received N1 or N2 had fewer cotton leaf worms; in the 7th and 9th weeks from sowing, Misr 10, Dr101 and H6L198 harbored fewer whiteflies. The lowest pod weight/plant, seed yield/plant, 100-seed weight, seed yield/ha and HI were obtained by using N3. Higher biological yield/ha, seed yield/plant, 100-seed weight, seed yield/ha and HI were attained by Misr 10. In the second season, seed yield per plant and seed yield per hectare were significantly affected by the interaction between soybean genotypes and mineral N fertilizer rates. Growing Misr 10 with 67 per cent N of the recommended rate increased seed yield/plant and seed yield/ha, along with fewer cotton leaf worm, whiteflies and leaf miners compared to the commercial cultivar Giza 111 receiving the recommended mineral N fertilizer rate.

Yield Response and Barley Grain Quality to Nitrogen Fertilization in West Arsi Highland of Ethiopia

The malting industry in Ethiopia is often challenged by the availability of barley that meets the quality and quantity requirements set by the industry. Field experiments were conducted to evaluate the effects of mineral nitrogen fertilizer rates on Actual yield and quality response of malt barley varieties and, to determine economic optimum rates of nitrogen fertilizer for the productivity of the crop arranged in randomized complete block design in factorial arrangement with three replications. The treatments are three malt barley varieties, namely Traveler, Ibon and Local and four levels of N (0 kg N/ha, 50 kg N/ha, 100 kg N/ha and 150 kg N/ha. The study revealed that nitrogen fertilization with 150 kg ha-1nitrogen fertilizer rate improved barley yield and quality than the rest nitrogen fertilizer rates. The different barley varieties and nitrogen fertilizer has shown a highly significant (p<0.01) influence on barley yield production. On the other hand, interaction effect of barley varieties and nitrogen fertilizer didn’t show significant variation barley yield production. Moreover, the analysis of variance also revealed that barley varieties have shown a highly significant (p<0.01) influence on barley yield production. The maximum and minimum interaction mean values of actual grain yield were observed from traveler barley variety treated with 150 kg ha-1nitrogen fertilizer rate (2078.10 kg/ha) and Ibon barley variety treated with 0 kg ha-1nitrogen fertilizer rate (1136.30 kg/ha), respectively. In the present investigation, quality parameters increased with an increase in N rates, application of 150 kg N ha-1 gave the highest quality parameters studied except sieve test. While, the quality parameters was less pronounced with the tested varieties and their interaction effect. The partial budget analysis revealed maximum net benefit of (Birr 39147 ha-1) with an acceptable marginal rate of returns (MRR) of 1007.33% with the treatment traveler variety with combination of 150 kg N ha-1. However, the lowest net benefit of (Birr 22726.00 ha-1) was recorded from Ibon barley variety treated with 0 kg ha-1nitrogen fertilizer rate. Both grain yield and protein content increased with increased N rates application of 150kg N ha-1 gave the highest net benefit and marginal rate of return with acceptable grain quality (protein content < 9-12%). Therefore, production of traveler variety with a combination of 150 kg N ha-1 was economical, and uncertainly recommended for production of malt barley in the study area.

Competitive Relationships and Yield Advantage of Intercropping Faba Bean with Sugar Beet under Bio-Organic Additives and Mineral Nitrogen Fertilizer Rates

A field experiment was conducted at El-Serw Agricultural Research Station, Damietta Governorate, Egypt during 2016/2017 and 2017/2018 seasons to reduce mineral N inputs of sugar beet with increased land use efficiency and profitability under intercropping conditions. Seven treatments included five treatments (90 kg nitrogen “N” + 30 m3 farm yard manure “FYM”/fad, 80 kg N +30 m3 FYM/fad, 70 kg N +30 m3 FYM/fad and 400 g of Cerealine + 30 m3 FYM/fad for intercropping faba bean cultivar Spanish with sugar beet cultivar Gloria) and two treatments (90 and 20 kg N/fad for solid culture of sugar beet and faba bean, respectively, as recommended mineral N fertilizer rate) were compared in a randomized complete block design with three replications. Solid culture of sugar beet with the application of recommended rate (90 kg N/fad) gave the highest top, root and sugar yields/fad, as well as the percentage of purity compared with the other treatments in both seasons. Intercropping faba bean with sugar beet plants with application of 90 kg N + 30 m3 FYM/fad gave the highest number of leaves/plant, leaf area/plant, root length, root diameter and root weight/plant followed by intercropped sugar beet plants that fertilized with 80 kg N + 30 m3 FYM/fad compared with the other treatments in both seasons. On the other hand, intercropped sugar beet that received 400 g of Cerealine + 30 m3 FYM/fad had the highest percentages of T.S.S. and sucrose followed by 70 kg N + 30 m3 FYM/fad compared with the other treatments in both seasons. Solid culture of faba bean with the application of 20 kg N/fad gave the highest plant height, number of seeds/pod and seed yield/fad, meanwhile the highest number of branches/plant and pod length were achieved by intercropping faba bean with sugar beet with application of 90 kg N + 30 m3 FYM/fad followed by intercropped faba bean plants that fertilized with 80 kg N + 30 m3 FYM/fad compared with the other treatments in both seasons. However, intercropped faba bean plants that fertilized with 70 kg N + 30 m3 FYM/fad gave the highest number of pods per plant, number of seeds per pod, seed index and seed yield per plant compared with the other treatments in both seasons. Land equivalent ratio (LER), land equivalent coefficient (LEC) and relative crowding coefficient (RCC) were high by intercropping faba bean with sugar beet with the application of 80 kg N + 30 m3 FYM/fad indicating yield advantage was achieved. The value of aggressivity (Agg) of sugar beet was negative for all combinations indicating that sugar beet is dominated component in the present study. Intercropping faba bean with sugar beet with the application of 80 kg N + 30 m3 FYM/fad achieved higher total income and monetary advantage index (MAI) than the other treatments. Growing sugar beet plants in both sides of beds (1.2 m width) with one faba bean row in middle of sugar beet beds with the application of 80 kg N + 30 m3 FYM/fad decreased mineral N fertilizer rate by 10.00% of the recommended sugar beet mineral N fertilizer rate, as well as increased land usage and profitability for Egyptian farmers compared with sugar beet solid culture.

Effect of different types of biochar on soil chemical properties , microbial community, pathogenic fungi and faba bean productivity

This experiment was carried out in sandy loam soil of private from at Romana , North Sinai Governorate, Egypt during two successive winter seasons 2017 / 2018 and 2018 /2019, to study the effect of three types of biochar, (A) produced from corn stalk, straw rice , straw of faba bean and cotton stalk, (B) produced from trees stalk and (C) town refuse, with three levels from Urea fertilizer (0, 20, 30 Kg N/fed), plus control treatment which received the recommended dose of urea (46 %N), to examine the effects of biochar types combined with or without nitrogen fertilizer on faba bean productivity under saline soil conditions. Faba bean variety Giza 843 were sowed on 12 November 2017 and 2018The experiment was carried out in a split plot design with three replicates. The used to three biochar types were arranged randomly as sub plot, were different rates of mineral nitrogen fertilizer was distributed randomly as main plot. Results obtained that, the combination between biochar types with different levels of N fertilizer enhanced all tested parameters. Moreover, biochar type (C) with level 30 Kg N/fed recoded the highest values of all tested parameters. On the other hand, the same treatment was the most effective on the root rot and wilt incidences, where the survival plants was % 97.9 and 93.4 respectively and decreased the number of the pathogenic fungi.

Influence of Conventional and Intensive Cropping Sequences on Wheat Productivity under Different Mineral Nitrogen Fertilizer Rates

A two-year study was conducted at Sakha Research station, Agricultural Research Center (ARC), Kafr El-Shiekhgovernorate, Egypt during 2013/2014 and 2014/2015 to decrease mineral nitrogen (N) inputs of wheat crop. This studyincluded two experiments each one contained 9 treatments, which were combinations of three cropping sequences(summer crop/Egyptian clover fahl''/wheat, summer crop/fodder maize/wheat and summer crop/fallow/wheat) and threemineral N fertilizer rates (80 kg N/fad, 60 kg N/fad + ascobien and 40 kg N/fad + ascobien). A split plot design with threereplications was used and combined analysis was done for the two experiments in each season. The results showed thatthere were clearly insignificant differences between rice and maize as a preceded summer crop on grain yield of wheatplants. The cropping sequence (maize or rice /Egyptian clover fahl''/wheat) increased significantly all the studied wheattraits compared with the other copping systems in the two seasons. There were insignificant differences betweenapplication of 80 kg N/fad and 60 kg N/fad + ascobien for grain yield/fad in the two seasons. The optimum grain yield/fadwas obtained by growing Egyptian clover fahl'' during transition period between preceded maize or rice in the summerseason and wheat that fertilized by 60 kg N/fad + ascobien in the winter season.

Effect of Bio-Organic Additives and Mineral Nitrogen Fertilizer Rates on Nitrogen, Phosphorus and Potassium Uptake by Sorghum with Aid of 15N Stable Isotope

A pot experiment was conducted in the green house to evaluate the response of sorghum crop grown on newly reclaimed sand soil to different organic additives in combination with biofertilizer Azotobacter chroococcum and different rates of mineral-N. Straw and root dry weight was stimulated by bacterial inoculation combined with high rate of mineral fertilizer (40 mg N pot-1). Nitrogen uptake by straw and root was gradually increased with increasing fertilizer-N rates. Similar enhancement effect of organic fertilizers and bacterial inoculation was also recognized with high N rate. P uptake by plants was positively enhanced by nitrogen fertilizer application, compost and chicken manure additives. Reversibly, bacterial inoculation has no positive effect on P uptake by either straw or root. Potassium uptake was not varied as affected by organic additives. But, to some extent, it was enhanced by increasing the nitrogen fertilizer rates. Generally, bacterial inoculation has no positive effect on K uptake by either straw or root. Chicken manure was the best in releasing mineralized N (Ndforg) to inoculated plants, followed by leucaena residue then compost. In case of the un-inoculated plants, the release of N from chicken manure surpasses those of compost whereas leucaena residues came to the next. N derived from mineral fertilizer was significantly affected by mineral fertilizer rates and to some extent by organic types. Increases of %Ndff in the uninoculated plants confirmed its dependence mainly on N gained from mineral fertilizer rather than other sources like those derived from organic additives or soil.

Effect of Some Soil Additives and Mineral Nitrogen Fertilizer at Different Rates on Vegetative Growth, Tuber Yield and Fixed Oil of Tiger Nut (Cyperus esculentus L.) Plants .

A pot experiment was carried out in the Experimental Station of Horticulture and Medicinal and Aromatic Plants, Fac. Agric., Mansoura Univ., during the two summer seasons of 2014 and 2015 to study the effect of different soil additives(rice straw compost (R.S.C.), town refuse compost (T.R.C.) and bio-fertilizer nitrobien) and different rates of mineral nitrogen fertilizer (ammonium sulfate (20.6% N) at 0, 50, 100 and 150 kg/fed) on vegetative growth, tuber yield , fixed oil percentage and compositionof tiger nut (Cyperus esculentus L.) plants. The results indicated that (R.S.C.or T.R.C.) fertilizer at the rate (15 m3/fed) plus nitrobien at the rate of(4 kg/fed) had a positive effect on vegetative growth of tiger nut plant; expressed as plant height (cm), number of tillers/pot, herb dry weight (g/pot) and harvesting characters including number of tubers/pot, tuber yield (g/pot), fixed oil percentage and oil yield (ml/pot), compared with other soil additive treatments.In addition,R.S.C. fertilizer was more effective on all studied characters in both seasons than either T.R.C. or nitrobien treatment. The highest level of nitrogen fertilizer (150 kg/fed) significantly enhanced all vegetative growth characters and some harvesting characters including tuber yield (g/pot) and fixed oil yield (ml/pot), but the maximum number of tubers per pot, fixed oil % were obtained from plants treated with nitrogen fertilizer at rate of 100 kg/fed compared with the other levels of nitrogen fertilizer. The combined treatment of 150 kg/fed nitrogen fertilizer with R.S.C. plus nitrobien was the most effective treatment to improve vegetative growth and harvest characters including tuber yield (g/pot), fixed oil yield (ml/pot), followed by the same combination using 100 kg/fed nitrogen fertilizer instead of 150 kg/fed nitrogen fertilizer with non-significant differences between the two treatments. The combined treatment of 100 kg/fed nitrogen fertilizer with R.S.C. plus nitrobien was more effective on number of tubers per pot, fixed oil % than any individual or combination treatments in both seasons. The gas liquid chromatography (G.L.C.) analysis identified twelve fatty acids in tiger nut fixed oil: six unsaturated fatty acids (oleic, linolinc, gondoic , palmitoleic , α-linolenic and heptadecenoic acids),as ranged from 78.50 to 79.21% of the oil and six saturated fatty acids (palmatic , stearic, myristic, arachidic, behenic and margaric acids),as ranged from 20.80 to 21.81%. The main components of the unsaturated fatty acids in tiger nut fixed oil were oleic acid (67.42-69.19 %), linolenic acid (9.42 – 10.27%), while the main saturated fatty acids in the fixed oil were palmatic acid (12.29 – 13.26 %) and stearic acid (6.60 – 8.13%).

Influence of Three Cropping Sequences and Mineral Nitrogen Fertilizer Rates on Flax Productivity and Profitability Under Different Planting Dates in Sandy Soil

The development of modern ecologically and profitable management for flax has a significant importance. A two-year study was carried out at Ismailia Agricultural Experiments and Research Station, ARC, Ismailia governorate, Egypt during 2013/2014 and 2014/2015 seasons to decrease mineral nitrogen (N) inputs of flax with increasing profitability for Egyptian farmer under different cropping sequences and planting dates in sandy soil. This experiment included 27 treatments which were the combinations of three cropping sequences (peanut / flax, peanut /fahl berseem/ flax and peanut / fodder maize / flax), three flax planting dates (5th November, 15th November and 25th November) and three mineral N fertilizer rates (107.1, 142.8 and 178.5 kg N/ha). A split split plot distribution in randomized complete block design was used. The results indicated growing fahl berseem in the transition period between peanut and flax increased plant height, technical length of the main stem, number of capsules per plant, number of seeds per capsule, 1000 – seed weight, seed yields per plant and per ha and oil, straw and fiber yields per ha in comparison with those grown after peanut or fodder maize. On the other hand, growing flax after peanut or fodder maize increased flax seed oil content. Seed, oil, straw and fiber yields per ha were decreased with delaying planting date of flax. The highest mineral N fertilizer rate had the highest values of plant height, technical length of the main stem, number of capsules per plant, number of seeds per capsule, 1000 – seed weight, seed yields per plant and per ha and oil, straw and fiber yields per ha. Conversely, flax seed oil content was decreased by increasing mineral N fertilizer rates. With regard to all the interactions of this study, all the studied traits of flax were affected significantly by all the interactions. Growing flax plants in the early date (5th November) after cutting fahl berseem gave the highest seed, oil, straw and fiber yields per ha with decreasing mineral N fertilizer rate per ha by twenty five percent under sandy soil conditions.

Advantages of Intercropping Soybean with Maize Under Two Maize Plant Distributions and Three Mineral Nitrogen Fertilizer Rates

The advent of further bioengineering for growing soybean with maize holds only promise for the future of the crop intensification field. The present research studied responses of maize crop and its yield attributes to decrease mineral nitrogen (N) inputs by growing soybean with two maize plant distributions under three cropping systems. Local maize variety T.W.C. 310 was grown under intercropping and sole cultures in one row/ridge in one and two plants/hill spaced at 30 and 60cm, respectively, that received three mineral N fertilizer rates (4, 5 and 6 g N/plant), while local variety of soybean seeds Giza 82 were drilled in two rows/ridge. A split – split – plot design with three replications was used. Light intensity with in maize canopy, ear leaf N and indole acetic acid (IAA) contents were affected by all the studied factors. Mixed pattern increased grain yields per plant and per ha by 1.56 and 3.98 %, respectively, in comparison with sole culture in addition to yielding 1.74 ton/ha of soybean. Increasing number of plants from one to two plants/hill by increasing plant spacing from 30 to 60 cm increased grain yields per plant and per ha. There were no significant differences between the medium and the highest mineral N fertilizer rates for all the studied traits. Soybean improved N use efficiency (NUE) for maize plant of mixed pattern. The mixed pattern had a total yield increase of 29.79 % than sole maize. Growing soybean on both sides of maize ridge that distributed to two plants/hill spaced at 60 cm decreased 47.6 kg N/ha of the recommended mineral N rate of maize plants which formed the best bioengineered treatment under Egyptian conditions.

CREATE ENVIRONMENTAL CONDITIONS FOR SUGAR BEET PRODUCTION BY ADDING BIO AND ORGANIC FERTILIZER UNDER NEWLY RECLAIMED SALINE SOIL IN NORTH SINAI.

Two field experiments were conducted in Galbana village, North Sinai Governorate during two winter seasons 2011/2012 and 2012/ 2013, to evaluate the environmental effect of mineral nitrogen fertilizer rate, compost and bio-fertilizer on some soil properties and sugar beet productivity under newly reclaimed saline soil.Theseeds of sugar beet (Beta vulgaris) variety Loilwere inoculated with Rhizobium radiobacter strain (salt tolerant PGPR). Results indicated that the soil pH was not significant as affected by bio-fertilizer or compost alone or in combination with different rates of mineral nitrogen fertilizer. The soil salinity decreased with increasing rate of mineral nitrogen combined with bio-fertilizer or compost. The relative increases of soil available N content in soil due to mineral nitrogen fertilizer; compost and bio-fertilizer after sugar beet cultivation, followed the descending order: bio-fertilizer> compost > mineral N as compared with initial soil for available N content. The relative increases in both P and K followed the descending order: compost > bio-fertilizer > mineral N fertilizer as compared with soil initial contents of P and K. The available micronutrients ie Fe, Mn, and Zn in soil were not significantly affected by the different fertilization treatments in both the first and second seasons. Also, available Fe was not significantly affected with rate of the used fertilizers whereas the effects of different rates on the available contents of both Mn and Zn were significant in the second season, however in the first one such rates were of significant effect of Zn only. The interactions among bio-fertilizer, compost and mineral nitrogen rates were of significant effects on Mn content in soil in both seasons whereas such an effect was significant on Fe in both seasons and Mn in the first one. The highest mean values of fresh and dry root yield, sugar yield, total soluble solids (TSS), purity and sucrose were achieved due to treating soil with bio-fertilizer together with the mineral nitrogen fertilizer. The highest values of N (1.14 %) concentration in root was observed at soil treated with compost plus 100 kg mineral N fertilizer, while the maximum values of P and K concentration (0.28 % for P and 1.29 % for K ) was observed as affected by bio-fertilizer plus 100 kg mineral N, respectively. On the other hand, the effect of all treatments tested on Fe, Mn and Zn concentration in root of sugar beet was non significant. As a conclusion, bio-fertilizer and compost application in sugar beet could increase characteristics of sugar beet root and reduced consumption of mineral nitrogen fertilizer and successfully reduced the hazard effect of soil salinity condition.

IMPACT OF MINERAL, ORGANIC AND BIOFERTILIZATION ON GROWTH , YIELD AND QUALITY OF CANTALOUPE

Two field experiments were carried out in a private farm at Gamassa district, Belqas Center, Dakahlia Governorate, Egypt, during the two successive summer growing seasons of 2013 and 2014 to study the effect of mineral nitrogen fertilizer rates, organic manure and foliar fertilization treatments with biofertilizers , biostimulants as well as their interactions on growth and yield of cantaloupe cv. Primal. The field experiments were laid-out in strip-split plot design with three replications. The most important results obtained from this investigation can be summarized as follows: Increasing mineral nitrogen fertilizer rates from 75 to 100 and 125 kg N/fed tended to increase growth, yield and its components, thus the highest values of these characters were resulted from adding the highest rate of nitrogen fertilizer (125 kg N/fed) in both seasons. Organic fertilizing of cantaloupe plants with chicken manure at the rate of 15 m3/fed significantly increased growth, yield and its components as compared with control treatment (without organic manure) in both seasons. Foliar spraying cantaloupe plants with yeast extract at rate of 5g /1L significantly surpassed other treatments (without, spraying with EM or Agrispon) and produced the highest values of all studied growth, yield and its components in both seasons. It can be recommended that organic fertilizing cantaloupe with 15 m3 chicken manure/fed and foliar spraying plants with yeast extract and mineral fertilizing with 100 kg N/fed in order to increase cantaloupe yield over the control treatment and reduce the environment pollution and production costs under the environmental conditions of Dakahlia Governorate, Egypt.

IMPACT OF HUMIC ACID AND MINERAL NITROGEN FERTILIZATION ON SOIL CHEMICAL PROPERTIES AND YIELD AND QUALITY OF SUGAR BEET UNDER SALINE SOIL.

Two field experiments were conducted at Gelbana district Sahl–El Tina plain (North Sinai) laying between longitudes 32 o 20 and 32o 33 east and latitudes 30 0 57 and 310 04 North during two successive seasons 2011/2012 and 2012/2013 to study the effect of soil application of inorganic nitrogen fertilization at rates of 50, 75 and 100 kg N fed -1 and organic humic acid fertilizer at rates of (0- 10 kg fed-1)and its impact on some chemical soil properties, growth, chemical composition, yield and quality of some sugar beet varieties (Mirador, Panther and Athospoly). A split- split plot design with three replicates was used in the two seasons. The highest values of available K content in soil in both seasons and available N content in the 1st season were recorded by Panther variety. Panther variety occurred a significant superiority over the other varieties in vegetative traits i.e. diameter, weight, dry matter %, of root, photosynthetic pigments i.e. chlorophyll a, b and carotenoides and proline as will as root and sugar yields in the two season. All quality parameters (total soluble solids %, sucrose% and juice purity %) were insignificantly affected by the tested varieties in the two seasons. Soil application of humic acid exhibited significant increase in available K-content in the soil in both seasons and available N in the 2nd season as will as N, P and K- percentages in sugar beet root in both seasons. Also application of humic acid significantly increased proline concentration in leaves beet by (15.73 and 13.97%), sucrose% by (0.41 and 0.61%), as will as root yield by (22.80 and 28.38 %) and sugaryield by (26.56 and 32.44%) in the 1st and 2nd seasons compare with untreated one. Increasing mineral N-rate significantly increased root and sugar yields/fed in both seasons. Also application of 100 kg N fed -1 recorded the highest values of root yield ( 29.91 and 27.27 ton fed -1) and sugar yield ( 5.53 and 4.71 ton fed -1) in the 1st and 2nd seasons. The interaction between mineral nitrogen fertilizer rates and humic acid (NXH) had a significant effect on root and sugar yields, sucrose%, and proline concentration in both seasons as will as on available K in the soil in the 1st season. However, the interaction between sugar beet varieties and nitrogen fertilizer (VxN) and between sugar beet varieties and humic acid (VxH) had a significant effect on root length, LA, chlorophyll a and carotenoides, proline concentration and root and sugar yields in both season. Meantime, the interactions effects between the three variables under study (sugar beet varieties, humic acid and mineral nitrogen fertilizer rates) insignificantly effected on all traits under studies.

Multi-scale trade-off analysis of cereal residue use for livestock feeding vs. soil mulching in the Mid-Zambezi Valley, Zimbabwe

Cereal residues represent a major resource for livestock feeding during the dry season in southern Africa. When kept on the soil surface instead of feeding them to livestock, crop residues can contribute to increasing soil fertility and maintaining crop productivity in the short- and the long-term. We explored these trade-offs for smallholder cotton–sorghum farming systems in the semi-arid Zambezi Valley, northern Zimbabwe. The analysis was done using simulation models at three scales, the plot, the farm and the territory, to simulate the effects of different sorghum residue allocations to livestock feeding vs. soil mulching, in combination with different application rates of mineral nitrogen fertilizer on crop productivity. The plot-scale simulations suggest that without N fertilization soil mulching has a positive effect on cotton yields only if small quantities of sorghum residues are used as mulch (average cotton yields of 2.24±0.41kgha−1 with a mulch of 100kgha−1 vs. 1.91±0.29kgha−1 without mulch). Greater quantities of mulch have a negative effect on cotton yield without N fertilization due to N immobilization in the soil microbial biomass. With applications of 100kgNha−1, quantities of mulch up to 3tha−1 have no negative effect on cotton yield. Results at farm-scale highlight the fundamental role of livestock as a source of traction, and the need to feed a greater proportion of sorghum residues to livestock as herd and farm sizes increase. Farmers with no livestock attained maximum crop production when 100% of their sorghum residue remained in the field, as they do not have access to cattle manure. The optimum fraction of crop residue to be retained in the fields for maximum farm crop production varied for farmers with 2 or less heads of cattle (80% retention), with 2–3 heads (60–80%), with 4 or more heads (40–60%). At the scale of the entire territory, total cotton and sorghum production increased with the density of cattle, at the expense of soil mulching with crop residues. The results of our simulations suggest that (i) the optimum level of residue retention depends on the scale at which trade-offs are analyzed; (ii) the retention of all of the crop residue as mulch appears unrealistic and undesirable in farming systems that rely on livestock for traction; and (iii) crop residue mulching could be made more attractive to farmers by paying due attention to balancing C to N ratios in the soil and by promoting small-scale mechanization to replace animal traction.

Fertilization of spring barley by combination of pig slurry and mineral nitrogen fertilizer

SUMMARYField experiments at Askov and Lundgaard Experimental Stations, Denmark, were carried out in 1987–91. Winter and spring applications of pig slurry at two application rates and an unfertilized treatment were combined with three rates of mineral nitrogen fertilizer; 15 treatment in all. Grain and straw yield, nitrogen content and nitrogen uptake of spring barley were measured at harvest. All main effects were significant, resulting in increasing yield and nitrogen uptake both when increasing the rate of mineral nitrogen fertilizer and slurry, and when slurry was applied in spring rather than in winter. The nitrogen content of the barley was affected by mineral nitrogen fertilizer application, and by the rate of slurry. The nitrogen efficiency of applied ammonia-N in the pig slurry was estimated by a quadratic polynomial yield response function and expressed relative to a reference function based on the application of mineral nitrogen fertilizer. The efficiency was estimated at 10 for spring-applied pig slurry. The value for winter-applied pig slurry was lower (0·6) and more variable. The efficiency of ammonia-N in spring-applied pig slurry decreased by 0·4/100 kg N/ha when supplementary mineral nitrogen fertilizer was applied at the same time.