Soil management for crop production in the West African Sahel. II. Emergence, establishment, and yield of pearl millet

Crop establishment is an important yield factor for pearl millet in the Sahel. Therefore, we conducted a series of experiments to determine the effects of seed size, depth and method of planting, millet variety, pre-sowing tillage, and soil fertilization upon seedling emergence, crop establishment, and yield. All experiments were conducted on a sandy Psammentic Paleustalf in Niger.

For all three millet varieties studied, out of a range of sowing depths from 1 to 7 cm, a sowing depth of 3–5 cm resulted in the highest percentage emergence, the highest above-ground biomass, and most secondary roots. High soil temperatures are common during establishment, typical maximum temperatures at a depth of 1 cm exceed 46°C. The adverse effects of wind erosion were least when sowing in hills; establishment, crop stand survival, and yield were better under hill planting than drilling seed.

Pre-sowing tillage increased initial stands and their survival, the latter also depending on fertility. Thus, improved crop yields result from better stand survival and higher yields per hill. Fertilizer application of 17 kg ha⁻¹ P and 40 kg ha⁻¹ of N tripled grain yields. Ridging without prior tillage and plowing increased grain and stover yields two- to three-fold. In combination with fertilizer application, sixfold yield increases were obtained.

If pre-sowing tillage is considered, then, in view of the time limitations, ridging without prior tillage would be preferable to plowing, as it is a much faster operation giving equally good results in terms of crop establishment and yield.     

Natural occurrence of Pseudomonas aeruginosa,a dominant cultivable diazotrophic endophytic bacterium colonizing Pennisetum glaucum (L.) R. Br.

Endophytic microbial communities can have strong influence on the growth of their host plants. The present study reports a diazotrophic endophytic bacterial species that colonizes predominantly Pennisetum glaucum (pearl millet) and remains stabilized throughout the latter's various growth stages under field conditions. Qualitative and quantitative changes in the endophytic bacterial population structure were examined during the plant growth period at regular intervals of 7 days up to harvesting. DNA fingerprinting (ERIC-PCR) was used as a biomarker to track the identity of various isolates obtained at different time intervals. Identification of representative bacterial species corresponding to different ERIC types was made on the basis of 16S rRNA gene sequence analysis. Based on the colony forming unit (cfu) count of bacterial isolates observed at various growth stages, Pseudomonas aeruginosa PM389 was found to be the dominant diazotrophic species among the cultivable endophytes colonizing pearl millet. The population of P. aeruginosa was detected in the host 21 days after sowing (DAS), indicating its entry in plant roots from soil and suggesting its non-vertical transfer in pearl millet. Moreover, an upward migration of this dominant diazotrophic bacterial species to shoots was observed with the plant growth. Further evaluation of P. aeruginosa PM389 revealed its various plant growth promoting properties viz. nitrogen fixation, mineral phosphate solubilization, siderophore production and antagonistic properties.     

Association of Azospirillum brasilense with pearl millet (Pennisetum americanum (L.) Leeke)

Summary Microscopic observations of the root system of pearl millet (Pennisetum americanum (L.) Leeke) var. BJ 104 after surface sterilization and incubation in phosphate malate triphenyl tetrazolium chloride (TTC) revealed extensive colonization by Azospirillum spp. when plants were grown in sterile, partially sterile and field conditions as evidenced by the TTC-reducing property of active cells of the bacterium. Quantitative studies showed the need to standardize the techniques further to ensure more precise monitoring of the bacteria in the rhizosphere, as large numbers of soil bacteria were found capable of growth on specific media, thus interfering with the plate counts. Seed inoculation with A. brasilense increased the mean grain yield of pearl millet under different agroclimatic conditions in India. The mean increase in grain yield due to inoculation over uninoculated controls was also noticed with graded levels of fertilizer nitrogen (urea). Inoculation alone contributed to increased nitrogen uptake of plants with varying levels of fertilizer nitrogen application under sandy loam soil conditions (pH 7.3). The effects of inoculation were more prominent under lower levels of nitrogen than at the higher levels. The root biomass under field conditions was increased with Azospirillum spp. inoculation at 10 and 20 kg N/ha than their corresponding uninoculated controls.     

不同播期下低芥酸油菜利用氮肥的研究

应用~(15)N示踪法,对甘蓝型油菜(Brassica napus L.)低芥酸品种“中油低芥三号”在不同播期下对氮肥的利用进行了研究。结果表明,在正常播期范围内,早播油菜比晚播油菜的氮吸收总量,吸收自肥料氮的百分率、氮肥利用率、氮肥生产效率、磷吸收量和磷生产效率都明显增加。因此生物产量、菜籽产量、产油量和含油率都显著提高。菜油中芥酸含量随播期推迟而稍有上升、但差异不显著。     

The phosphorus requirement of Amaranthus mangostanus L. exceeds the 'change point' of P loss

Due to the high economic value of vegetables, farmers in China often apply more fertilizer than is required for plant growth. This leads to phosphorus accumulation in soils, which can pollute the aquatic environment. This conflict arises because vegetables often use nutrients inefficiently, and require high phosphorus levels in the growth medium. In this study, amaranth ( Amaranthus mangostanus L.) was grown in soils with 14.7, 23.8, 45.3, 54.6, 74.2, 101 or 116 mg Olsen-P/kg, and with and without phosphorus fertilizer (175 mg P/kg or equivalent to 385 kg P/ha). The yield of amaranth was positively correlated with soil Olsen-P content. CaCl₂-P content was positively correlated with Olsen-P content and CaCl₂-P markedly increased at Olsen-P contents exceeding 53.8 mg P/kg in the pot experiment or 55.9 mg P/kg in the field survey. These values were regarded as the 'change points' for phosphorus loss; to achieve 85 or 95% of maximum amaranth yield, the amaranth crop required 91or 101 mg Olsen-P/kg soil, respectively, and application of 175 mg P/kg was still able to significantly increase amaranth yield at an Olsen-P level of 74.2 mg P/kg soil. These results indicated that the phosphorus requirement of amaranth exceeded the 'change point' (53.8 or 55.9 mg Olsen-P/kg); the C _min (minimum concentration in the media at which no net influx occurs) of phosphorus for 3-week-old amaranth was 1.55 μ m . This value is much higher than that reported for other crops, and may explain the inefficient P use of amaranth. The high C _min value also indicates that the phosphorus requirement of amaranth is beyond the 'change point' of P loss.     

Nitrogen transfer from warm‐season annual legumes to pearl millet

A glasshouse study was conducted to determine and quantify direct transfer of nitrogen (N) between 3 selected warm‐season annual legumes and a warm‐season annual grass during the growing season, ‘Tifleaf’ pearl millet [Pennisetum americanum (L.) Leeke] was grown in pots as a monoculture with and without N applied as inorganic fertilizer, or with either ‘Iron and Clay’ cowpeas [Vigna unguiculata (L.) Walp], common alyceclover [Alysicarpus vaginalis (L.) DC.], or ‘Comanche’ partridge pea (Cassia fasciculata Michx.). Sixty‐three percent of the N contained in pearl millet grown with alyceclover was derived directly from alyceclover as determined by the ¹⁵N dilution technique. Partridge peas and cowpeas transferred 34% and 32%, respectively, of the N contained in companion pearl millet plants. Pearl millet grown with partridge peas produced dry matter yields similar to pearl millet that received the equivalent of 112 kg N/ha. Pearl millet grown with legumes contained lower levels of neutral detergent fiber than did pearl millet that received inorganic fertilizer. Nitrogen content of pearl millet grown with legumes was not as great as pearl millet that received N‐fertilizer.     

Irrigation and nutritional effect on growth and seed yield of coriander (Coriandrum sativum L.)

Optimum quantity of fertilizers and irrigation water to minimize the cost and increase the production is need of the day. Consequently, an experiment was conducted at CCS Haryana Agricultural University, Hisar during the winter season of 2014–15 and 2015–16 to study the effect of irrigation schedules and fertilizer levels on coriander. Irrigation at 25, 50, 75, and 100 days after sowing (DAS) gave higher growth and yield attributing characters, seed yield (16.48 q/ha), biological yield (50.79 q/ha), net return (Rs. 138,950.6), and benefit to cost ratio (2.36), which resulted in 40.9% and 15.3% increase in seed and biological yield over two irrigations, respectively. The application of fertilizers, i.e., N₆₀ and P₅₀ kg/ha, registered higher growth, seed yield attributes, consumptive use of water, whereas, net return and benefit to cost ratio was recorded maximum under fertilizers, i.e., N₇₅ and P_62.5 kg/ha. The interaction effect of irrigation and fertilizer on seeds per umbellet and seed yield was also found to be significantly positive. Hence, in Northern Plains of India four irrigations at 25, 50, 75, and 100 DAS in association with nitrogen 75 kg/ha and phosphorus 62.5 kg/ha is more profitable in coriander crop.     

The contribution of agricultural practices to nitrous oxide emissions in semi-arid Mali

The yield and flux of nitrous oxide (N₂O) emitted from continuous cereals (with and without urea), legumes/cereal in rotation and cereal/legume in rotation all with or without organic manure was monitored from January 2004 to February 2005. All treatments except continuous cereals had phosphate added. The cereal grown July–October in 2003 and 2004 was pearl millet ( Pennisetum glaucum) and the legume was a bean ( Phaseolus vulgaris ). The 10 m × 10 m plots were established in a semi-arid climate in Mali. The addition of organic manure and both inorganic fertilizers increased yield and N₂O emissions. Continuous cereals treated with both organic manure and urea emitted significantly less N₂O (882 g N/ha per year) than plots receiving no organic manure(1535 g N/ha per year). Growing N-fixing crops in rotation did not significantly increase N₂O emissions. This study supports the new practice of growing cereal and legumes in rotation as an environmentally sustainable system in semi-arid Mali.     

Cotton response to placement and rate of starter fertilizer

Application of starter fertilizer at‐planting is a convenient method of applying phosphorus (P) and pre‐plant nitrogen (N) to cotton (Gossypium hirsutum L.). In addition, the placement of starter fertilizer in‐furrow requires no extra tanks or pumps, and can be tank mixed with at‐planting insecticides, fungicides, or plant growth regulators. Over a four‐year period, tests were initiated to determine the effect of 10–34–0 starter fertilizer applied in‐furrow and in a 5 cm to the side and 5 cm below the seed placement (5 cm x 5 cm). Lint yields were measured all four years. Stand counts, Chambers’ skip index, and plant heights were measured the final year. Placement of starter fertilizer in‐furrow was shown to decrease yields compared to a 5 cm x 5 cm placement and a check two out of four years. Plant stands, skip indexes and plant heights were adversely affected by an in‐furrow placement as well. A 5 cm x 5 cm placement did not significantly differ in terms of yield in any year from the check. Plant stands and skip indexes were not affected, but plant height was increased over the check with one rate of starter placed 5 cm x 5 cm. Our results suggest that in‐furrow placement of starter fertilizer has the potential to negatively affect seedling growth and decrease yields. A 5 cm x 5 cm placement of starter fertilizer, while it may not increase yields, does not incur these risks and is a safe, convenient and inexpensive method of applying P or pre‐plant N.     

Effects of early mycorrhization and colonized root length on low‐soil‐phosphorus resistance of West African pearl millet

Phosphorus (P) deficiency at early seedling stages is a critical determinant for survival and final yield of pearl millet in multi‐stress Sahelian environments. Longer roots and colonization with arbuscular mycorrhizal fungi (AMF) enhance P uptake and crop performance of millet. Assessing the genotypic variation of early mycorrhization and its effect on plant growth is necessary to better understand mechanisms of resistance to low soil P and to use them in breeding strategies for low P. Therefore, in this study, eight pearl millet varieties contrasting in low‐P resistance were grown in pots under low P (no additional P supply) and high P (+ 0.4 g P pot^?1) conditions, and harvested 2, 4, 6, and 8 weeks after sowing (WAS). Root length was calculated 2 WAS by scanning of dissected roots and evaluation with WinRhizo software. AM infection (%) and P uptake (shoot P concentration multiplied per shoot dry matter) were measured at each harvest. Across harvests under low P (3.3 mg Bray P kg^?1), resistant genotypes had greater total root length infected with AMF (837 m), higher percentage of AMF colonization (11.6%), and increased P uptake (69.4 mg P plant^?1) than sensitive genotypes (177 m, 7.1% colonization and 46.4 mg P plant^?1, respectively). Two WAS, resistant genotypes were infected almost twice as much as sensitive ones (4.1% and 2.1%) and the individual resistant genotypes differed in the percentage of AMF infection. AMF colonization was positively related to final dry matter production in pots, which corresponded to field performance. Early mycorrhization enhanced P uptake in pearl millet grown under P‐deficient conditions, with the genotypic variation for this parameter allowing selection for better performance under field conditions.     

栽培模式对直播油菜生长、产量和养分吸收利用的影响

发展直播油菜对增加我国油菜种植面积和总产有重要意义,但栽培措施尤其是施肥技术的滞后极大地影响了油菜的产量及施肥效果。2009/2010年度在湖北省油菜主产区设置田间试验,研究栽培模式对直播油菜生长、产量、经济效益和养分吸收利用的影响,探讨适合当前生产的高产高效栽培技术。结果表明,各优化模式比农民习惯栽培模式均有增产增收效果,其中在30104 plant/hm2种植密度、秸秆还田和加强病虫草害防治的基础上进行优化施肥（氮、磷、钾肥用量分别为N 195 kg/hm2、 P2O5 90 kg/hm2、K2O 90 kg/hm2,硼砂用量15 kg/hm2,氮肥和钾肥分次施用）的模式Ⅲ表现最好,比农民习惯施肥增产35.9 %、增收1632 Yuan/hm2,地上部干物质量和养分累积也均较高,氮、钾肥偏生产力分别为N 13.7 kg/kg和K2O 29.8 kg/kg,实现高产高效目标。说明当前直播油菜的栽培模式应结合其生长发育进程和养分吸收规律,适当密植以增库促源,加强植保防治病虫草害,更重要的是积极推行平衡施肥和有机、无机配施,并合理安排施肥时期及比例。     

Fertilizer placement studies on calcareous and non‐calcareous chernozemic soils: Growth,P‐UP‐take,oil content and yield of Canadian rape

Abstract

Field experiments were conducted on calcareous and non‐calcareous Orthic Black Chemozemic soils over a five year period to study the effect of rates and placements of P‐fertilizer on Canadian rape (Brassica napus L. cv Tower) production. Six rates of P as mono‐ammonium phosphate (MAP) were applied at seeding using four placement methods: i) broadcast and cultivated 10 cm into the soil (BC); ii) banded in the seed row with the seed (PWS); iii) banded 2.5 below and 2.5 cm to the side of the seed (PSS); iv) banded 2.5 cm directly below the seed (PBS). Soil type had no significant effect on rape growth, seed yield and P‐uptake. Rape responded best to P‐fertilizer banded with (PWS) or near (PSS, PBS) the seed. But, placing 15 kg/ha P or greater with the seed reduced seedling emergence; with 25 kg P/ha insufficient plants emerged to justify harvesting. The reduced seedling emergence resulted in reduced seed yield and P‐uptake. Maximum yields were obtained when the fertilizer was banded 2.5 cm away from the seed (PSS, PBS). The BC method produced the least growth, yield and P‐uptake responses of the four methods. Only when broadcast rates of P were in excess of 10 kg/ha did rape dry matter, seed and P‐uptake increase. Banding 10 kg/ha with or near to the seed was equivalent to broadcasting 25 kg/ha in terms of seed yield and P‐uptake. Application of P fertilizer also increased seed protein and oil concentrations.     

群体和氮肥运筹对冬小麦产量和蛋白质组分的影响

采用二因素和单因素随机区组设计,研究基本苗和氮肥运筹对小麦植株性状、产量和蛋白质组分的影响。结果表明,不同基本苗和施氮量的处理间株高、穂长、穂粒数和产量均有显著差异。穂长与穂粒数呈极显著正相关(r=0.884**)。在播种偏晚的情况下,以基本苗较大和施氮量较多的组合（375×104/hm2,N 300 kg/hm2）产量表现最好;随基本苗增加穂长穂粒数和千粒重均逐渐减少。对产量而言,基本苗以375×104/hm2最为适宜, 但其与300×104/hm2基本苗和450×104/hm2基本苗处理的产量差异不显著。因此,生产中在偏晚的播期内,可以根据实际播种时间和地力条件,在300～450×104/hm2基本苗范围内调整。在施氮量150～300 kg//hm2范围内,随施氮量增加产量逐渐提高,处理间差异显著。在基本苗225～450×104/hm2范围内,谷蛋白和总蛋白含量均随基本苗增加呈逐渐降低的趋势,处理间差异显著;各种蛋白组分及总蛋白含量均随施氮量增加逐渐提高,除谷蛋白外,处理间差异均极显著。春5叶期追总施氮量50%的处理穂最长,穂粒数和产量最多,处理间差异显著;开花期追总施氮量50%处理的总蛋白含量最高,与春2叶期追总施氮量50%的处理差异显著。     

Response of mustard to seed treatment with pyridioxine and basal and foliar application of nitrogen and phosphorus

In a simple randomised field trial conducted during 1985–86/ 1986–87, the effect of basal nitrogen (45 and 60 kg N/ha) and basal phosphorus (15 and 20 kg P/ha) applications together with the soaking of seeds in 0.025% aqueous pyridoxine hydrochloride solution for 4h and foliar applications of 15 kg N/ha and 5 kg P/ha in two installments at 70 and 90 days after sowing (DAS) was studied on the performance of mustard (Brassica juncea L.). Recommended basal applications of 90 kg N/ha and 30 kg P/ha (BN₉₀P₃₀) was used as the control. The parameters studied included leaf area index (LAI) at 60, 80, and 100 DAS, net assimilation rate at 60–80 and 80–100 day intervals, and pods/plant, seeds/pod, seed yield, oil content, and oil yield at harvest. In general, the pyridoxine treatment proved superior over water soaking. The higher basal fertilizer dose was effective and foliar application of N and P gave higher values as compared to the water foliar application alone. The combination of pyridoxine + BN₆₀P₂₀+ FN₁₅FP₅ significantly enhanced the performance of the crop and enhanced seed yield and oil yield by 15.8 and 13.5%, respectively, over the check BN₉₀P₃₀ treatment.     

Response of soyabean (Glycine max Mer.) to wheat straw mulching in different cropping seasons

Abstract. The favoured temperature range for soyabean seed germination is 25–30 °C and the crop is sensitive to water stress. In northern India, the crop is sown in the hot-dry months of May–June. Straw mulching can alter the soil's hydrothermal regime by lowering the temperature and reducing evaporation losses. A field experiment was conducted from 1999 to 2002 at the Research Farm of Punjab Agricultural University, Ludhiana on a loamy sand soil to evaluate the effect of wheat straw mulch on soil temperature, soyabean seed yield and crop growth. Maximum soil temperatures at sowing depth, recorded during the 1-month period after sowing (seed germination to seedling establishment stage), were high under no-mulch, ranging from 30.6 to 48.6 °C, while mulching substantially reduced these temperatures by 1.4 to 12.7 °C. Mulching increased soyabean seed yield by 4.4 to 68.3% in different cropping seasons; it also increased plant biomass by 17 to 122% and nodule mass by 8 to 220%. Leaf area index, chlorophyll content of leaves and number of pods per plant were all increased. Seed yield improvement under mulch was negatively correlated with rainfall distribution (number of rainy days) and amount during the whole cropping season. The percentage increase in seed yield with mulching was regressed against the total number of rainy days and total rainfall in millimetres in the cropping season. Thereby 93% of the variation in response to mulching in different cropping seasons was explained by the distribution and amount of rainfall.     

Ammonia volatilization from Vertisols

Farmers want to minimize losses of nitrogen (N) by volatilization of ammonia when adding fertilizers and improve fertilizer recovery of N by plants. We aimed to quantify the losses of N through NH₃ volatilization as affected by soil moisture content, type of fertilizer, and placement method in Vertisols in Kenya, and conducted three experiments for the purpose under controlled conditions in the laboratory. We found that NH₃-N losses were greatest at 80% water holding capacity, which we ascribed to the ready availability of water to dissolve the fertilizer at that water content. The soil's cation exchange capacity (CEC) did not influence volatilization, whereas the soil's pH indicated the potential of the soil to volatilize ammonia. Ammonia losses from the fertilizers were in the order urea > ammonium sulphate > ammonium nitrate applied. Incorporating fertilizer within the 0–5 cm soil layer more than halved NH₃ volatilization but did not prevent it completely. These results indicate that soil pH, rather than CEC, is the main inherent characteristic influencing ammonia volatilization from Vertisols. Ammonium-based fertilizers should be incorporated within the 0–5 cm soil layer, or preferably somewhat deeper, to avoid losses via NH₃ volatilization, particularly in alkaline soils. Nitrate fertilizers are preferable to urea where the risks of NH₃ volatilization are large, provided due consideration is given to denitrification risks.     

Organically fertilized onions (Allium cepa L.): effects of the fertilizer placement method on quercetin content and soil nitrogen dynamics

Field-cured onions cv. Hyskin ( Allium cepa L.) supplied with organic nitrogen fertilizer were studied. The fertilizer was applied by broadcasting and harrowing, broadcasting and rotary cultivation, or placement between rows. Nitrogen dynamics were monitored throughout the growing season by soil sampling. Variation in quercetin content in the onion scales was analyzed by HPLC. The organically fertilized onions were compared with inorganically fertilized onions grown in the same field. Inoculation with arbuscular mycorrhizal fungi (AMF) in the row at sowing or during commercial transplant production was tested but did not significantly affect mycorrhizal root colonization levels in the field. Onions that received no fertilizer at all or that had fertilizer placed between rows had better establishment, probably due to more favorable soil nitrogen concentrations for seedling emergence. Broadcast application led to higher nitrogen concentration in the root zone, resulting in fewer but larger individual onions. Quercetin levels were not significantly altered as a result of nitrogen fertilizer source (inorganic or organic), application method, or mycorrhizal inoculation. However, variation between years was significant, with quercetin levels in 2004 almost twice as high as those in 2005.     

甘南高寒阴湿区宽幅匀播青稞“3414”肥效试验

为了将宽幅匀播技术与“3414”肥效试验相结合,应用于甘南高寒阴湿区青稞种植与示范推广中,推动该地区青稞种植产业发展。采用“3414”最优回归设计,以青稞甘青9号为指示品种,在宽幅匀播条件下研究了“3414”肥效试验对青稞生长及产量的影响,并建立了青稞产量与氮、磷、钾施量之间的肥效回归方程,以提高肥效,促进甘南高寒阴湿区青稞生产优质高产。结果表明,宽幅匀播条件下,甘青9号最佳产量为6 640.32 kg/hm2时,施肥量为N 36.34 kg/hm2、P2O5 55.86 kg/hm2、K2O 7.09 kg/hm2;最大产量为6 834.09 kg/hm2时,施肥量为N 80.66 kg/hm2、P2O5 62.31 kg/hm2、K2O 16.58 kg/hm2。肥效回归方程中施肥量与青稞产量拟合度显著,可应用于大田生产。     

Use efficiency of nitrogen from biodigested plant material by ryegrass

Apparent nitrogen‐use efficiency of the applied mineral N (NUE_min) in effluent from biodigested plant material (BE; C : N_org ratio 14:1; mineral N–to–total N ratio 0.5:1) and a nitrate‐based inorganic fertilizer (IF), both applied at two rates was investigated in a six‐month pot experiment with Italian ryegrass (Lolium multiflorum Lam.). Dry‐matter (DM) production was 7% lower and total amount of N in aboveground biomass was 8% lower in BE than in IF at 40 d after sowing (DAS), equal at 81 DAS, and higher in BE than in IF at 136 and 172 DAS. NUE_min calculated on the basis of accumulated N in aboveground biomass of ryegrass in fertilized treatments compared to a control without N application was significantly lower in BE than in IF up to the third cut (136 DAS). Total NUE_min, total N recovery, and amount of foliage DM were similar for both fertilizers at the end of the experiment. Root biomass, total DM produced including roots and stubble, the fraction of root N to total plant N, and soil mineral N at 172 DAS were higher for BE than for IF. Mineral N applied with biogas‐reactor effluent was almost as effective as the nitrate‐based mineral fertilizer used for comparison. Within the six‐month experimental period net N mineralization, estimated at 12% of organic N in effluent, was not substantial. Hence, the organic compounds in the effluent were relatively recalcitrant.     

Nitrate leaching and pasture yields following the application of dairy shed effluent or ammonium fertilizer under spray or flood irrigation: results of a lysimeter study

Abstract. Nitrate leaching and pasture ( Lolium perenne / Trifolium repens ) yields were measured on monolith lysimeters (80 cm diam. × 120 cm depth) of a Templeton sandy loam soil (Udic Ustochrept), following repeated applications of dairy shed effluent (DSE) or ammonium fertilizer (NH₄Cl), under spray (50 mm/month) or flood (100 mm/month) irrigation. Applications of DSE at 400 kg N/ha per annum resulted in significantly less nitrate leaching (8–25 kg N/ha per yr) compared with NH₄Cl (28–48kg N/ha per yr) ( P < 0.01). Over the two year period, the total mineral N (predominantly nitrate) leached was equivalent to 2.5–3.7% of the total N applied in the DSE and 8.7–9.8% of the N applied in the NH₄Cl. There was a trend of slightly less nitrate leaching under the flood irrigation than under the spray irrigation, probably because of the greater potential for denitrification under the wetter conditions. Average nitrate concentrations in the leachate were generally below the drinking water standard except in the NH₄Cl treatment under spray irrigation where it averaged 10 mg NO₃-N/l over the two year period. DSE was equally as effective as NH₄Cl in stimulating pasture dry matter production. Annual nitrogen uptakes were similar for the DSE (343 kg N/ha) and NH₄Cl (332–344kg N/ha) treatments in the first year but were higher in the DSE (361–412 kg N/ha) than in the NH₄Cl (324–340 kg N/ha) treatments in the second year. Pasture uptakes of phosphorus and sulphur were also higher in the DSE than in the NH₄Cl treatments in the second year. The results emphasize the need to set different regulatory limits for land application of organic wastes of various types and for N fertilizers.