Banding of Fertilizer Improves Phosphorus Acquisition and Yield of Zero Tillage Maize by Concentrating Phosphorus in Surface Soil

Zero tillage increases stratification of immobile nutrients such as P. However, it is unclear whether near-surface stratification of soil P eases or hampers P uptake by maize (Zea mays L.) which needs an optimum P supply at/before six–leaf–stage to achieve potential grain yield. The aim of the three-year study was to determine whether P stratification, under zero tillage, impaired yield of maize and which P placement methods could improve P uptake on an Aeric Albaquept soil subgroup. Phosphorus fertilizer was placed by: (a) broadcasting before final tillage and sowing of seeds; (b) surface banding beside the row; and (c) deep banding beside the row (both the band placements were done at three–four leaf stage) Phosphorus treatments were repeated for 3 years along with three tillage practices viz.: (a) zero tillage (ZT); (b) conventional tillage (12 cm; CT); and (c) deep tillage (25 cm; DT). In the third year, all the tillage practices gave similar yield of Bangladesh Agricultural Research Institute (BARI) hybrid maize–5, but the highest grain yield was obtained by surface band P placement. After three years of tillage and P placements, the root mass density (RMD) at 0–6 cm depth increased significantly from 1.40 mg cm−3 in DT under deep band placement to 1.98 mg cm−3 in ZT under surface band placement, but not at the other depths. The combination of ZT practices, with broadcast or surface band placement methods, produced the highest available, and total P, content in soil at 0–6 cm depth after harvesting of maize. Accordingly, a significant increase in P uptake by maize was also found with surface banding of P alone and also in combination with ZT. Organic carbon, and total N, also increased significantly at depths of 0–6 cm after three years in ZT treatments with P placed in bands. By contrast, CT and DT practices, under all placement methods, resulted in an even distribution of P up to 24 cm depth. Phosphorus application, by surface banding at the three–four leaf stage, led to increased P uptake at early growth and silking stages, which resulted in highest yield regardless of tillage type through increased extractable P in the soil. Even though ZT increased P stratification near the soil surface, and it increased plant available water content (PAWC) and RMD in the 0–6 cm depth, as did surface banding, it did not improve maize grain yield. Further research is needed to understanding the contrasting maize grain yield responses to P stratification.

Effect of form, placement and rate of N fertilizer, and placement of P fertilizer on wheat in Saskatchewan

On the Canadian prairies, the one-pass seeding and fertilizing no-till system is very common. However, the close proximity of the fertilizer to the seed can cause damage to the emerging seedlings due to a combination of a salt effect and/or ammonia toxicity. Manufacturers have responded by developing openers that allow placement of seed and fertilizer in separate bands. A 3-yr study was initiated in 2000 to determine the effect of nitrogen (N) form [urea (U) and anhydrous ammonia (AA)], placement [broadcast (Br), side-band (SB) or mid-row band (MRB)], timing (fall or spring) and rate (0 to 90 or 120 kg N ha-1), and phosphorus (P) placement (7 to 10 kg P ha-1) on plant density, seed and straw yield, seed protein content, and N uptake of spring wheat (Triticum aestivum L.) under no-till at four sites representing different agro-ecological zones in Saskatchewan. Rate of applied N had the most dominant effect on agronomic variables, while form, placement, and timing of application of N had minor effects. Generally, SB and MRB were comparable in terms of seed yield, N uptake and seed protein content. From a practical perspective, SB and MRB could be used with equal success with either U or AA. Side banding P produced responses similar to seed-placed P, except under very dry conditions where side banding was superior. In general, placement of urea in soil in a band was more effective than broadcasting, while fall banding can be less effective than spring banding.Key words: Anhydrous ammonia, N application timing, N form, N and P placement, N uptake, protein content, urea, wheat, yield

Phosphorus accumulation by field-grown canola crops and the potential for deep phosphorus placement in a Mediterranean-type climate

When the bulk of phosphorus (P) is located near the soil surface, spring drying of topsoil in Mediterranean-type climates can reduce P availability to crops and cause potential yield loss. In crop species that require a P supply during spring, deep-placement of P fertiliser has proved an effective method of improving P availability and grain yields; however, the spring P demand of field-grown canola (Brassica napus L.) and therefore potential response to deep P placement is not known. This study investigated the effect of deep- (0.17–0.18 m), conventional- (shallow, 0.07–0.08 m), split- (50% deep, 50% shallow), and nil-P fertiliser treatments on P accumulation and seed yields of canola in two field trials. In addition, a glasshouse experiment with different depths of P fertiliser placement and topsoil drying at different growth stages was conducted. In the glasshouse study, deep P placement resulted in greater P uptake by plants, but did not increase seed yields regardless of the time of topsoil drying. At the relatively high-soil-P field site (canola grown on residual P application from the previous year) in a dry season, there was no biomass response to any residual P fertiliser treatments, and P accumulation had ceased by mid flowering. At the low-P field site, P accumulation continued throughout flowering and silique-filling, and seed yields increased significantly (P ≤ 0.05) in the order of split- > deep- > shallow- > nil-P treatments. Improved seed yields in the split- and deep-P treatments appeared to be the direct result of enhanced P availability; in particular, P uptake during vegetative growth (winter) was higher in the treatments with deep P placement. A greater understanding of P accumulation by field-grown canola in relation to soil P properties is needed for better defining optimum P fertiliser placement recommendations.

Long-term effect of placement of fertilizer nitrogen and phosphorus on barley yields

An experiment that was established in 1990 to assess depth and method of placement of nitrogen (N) and phosphorus (P) fertilizer on the yield of continuous barley (with 1 yr interruption with canola in 1995) was continued to 2001. Annually, 80 kg N ha-1 were banded either at 7.5 to 10 or 15 to 17.5 cm depth alone or in combination with 40 kg P2O5 ha-1; the latter was either seedrow placed or banded with the N (dual banding), or split 1/2 in the seedrow and 1/2 in the band. An unfertilized control was maintained in all years. Temperature after seeding had a marked effect on the effectiveness of depth of N and P placement as well as the method of P placement. Shallow (7.5 to 10 cm depth) placement resulted in greater yields in 8 of the 11 yr that barley was grown and was never inferior to deeper placement (15 to 17.5 cm); this advantage was directly related to cooler-than-normal temperature after seeding. Cooler-than-normal temperatures also resulted in benefits from seedrow placed P; however, benefits were not as frequent as those obtained by either dual banding or splitting P between seedrow and the band. It would appear that overall benefits from banding P together with N (dual band), independently of the depth of banding, are greater than those from seedrow placing, as those benefits from the latter are less frequent and of considerably less magnitude. Key words: Band, dual band, seedrow, shallow, deep

Fertilizer N management and P placement effects on yield, seed protein content and N uptake of flax under varied conditions in Saskatchewan

In the Canadian prairies, producers prefer to seed and apply all fertilizer nutrients in one operation, but placement of fertilizers at high rates in the seed row can reduce crop emergence. Recently, specialized equipment has been developed to minimize or prevent damage to seedlings by maintaining a safe separation between seed and fertilizer. A 3-yr (2000 to 2002) field study was conducted to determine the effect of N formulation (urea and anhydrous ammonia), placement (broadcast, side-band and mid-row band), timing (fall and spring) and rate (0 to 90 or 120 kg N ha-1), and P placement (7–10 kg P ha-1) on plant density, seed and straw yield, seed protein content, and N uptake in seed and straw of flax (Linum ustatissimum L.) under no-till at four sites (Indian Head, Black Chernozem soil – Udic Boroll; Melfort, Dark Gray Luvisol soil – Mollic Cryoboralf; Swift Current, Brown Chernozem soil – Aridic Boroll; and Scott, Dark Brown Chernozem soil – Typic Boroll) in Saskatchewan. There was a significant increase at 10 of 12 site-years for seed yield, at 5 site-years for straw yield, at 12 site-years for seed protein content, at 11 site-years for seed N uptake, and at 8 site-years for straw N uptake with increasing N fertilizer rate, but the responses were generally small to moderate and varied with placement, form and timing of N application, and placement of P fertilizer in a few cases. Side-banded N fertilizer treatments reduced plant emergence at 3 site-years for urea and at 4 site-year for anhydrous ammonia, but the plant densities were considered adequate for optimum yield. Seed and straw yield, seed protein content, and N uptake in seed and straw were generally similar between side-banded and mid-row-banded N fertilizer, and also similar between urea and anhydrous ammonia in most cases.Occasionally, there was a trend of seed yield reduction with seed-placed P compared with side-banded P, side-banded urea was more effective than broadcast urea, and fall banded N less effective than spring side-banded N. In conclusion, there were few differences in the agronomic performance of urea vs. anhydrous ammonia and side-band vs. mid-row band. The findings did suggest that broadcast urea can be less effective than side-banded urea, fall banded N can be inferior to spring banded N, and seed-placed P can reduce seed yield compared with side-banded P. Key words: Anhydrous ammonia, flax, N application timing, N form, N and P placement, N uptake, protein content, urea, yield

Management of nitrogen and phosphorus fertilizer in no-till flax

The major flax-growing areas of Canada coincide with areas where large shifts towards conservation tillage have occurred. These shifts have also brought about major changes in the way fertilizer is applied. The objective of this study was to determine the combination of nitrogen fertilizer form and N and P fertilizer placement methods that can increase N and P uptake, seed yield and seed oil concentration and composition in flax. The study was conducted at four locations covering the flax-growing areas over a 3-yr period. Three fertilizer forms, ammonium nitrate (AN), ammonium sulphate (AS) and urea were compared using different placement methods, pre-plant band (Pp) or side-band (Sb) in combination with monoammonium phosphate in either a Pp, Sb or seed-placed (Sp) position. Plant uptake of N and P was measured at 7, 14, 21 and 28 d after crop emergence and at the start of flowering. Other variables collected included crop establishment, crop yield and seed oil concentration and composition. AS resulted in the highest N uptake followed by AN then urea. As well, AS in the Sb showed higher N uptake than when applied Pp. The largest uptake of P was observed on days 7, 14 and 21 when AS and P were placed together in an Sb position. Crop establishment was adversely affected by urea and least by AN and AS, indicating that adequate seed-fertilizer separation between urea and flax seed is critical to minimizing reductions in plant stands. N form and placement, and P placement had no effect on seed oil concentration and composition in this study. Seed yield was improved marginally, overall, with the addition of P, while changes in N and P placement had no overall yield benefits. Treatments that resulted in improved N and P uptake in the first 21 d after crop emergence did not result in improved seed yields. When site × year interactions were investigated, 2 of 12 site years showed better yields when N and P were placed together in the Sb position. Based on the results of this study, we conclude that flax growers have many agronomically acceptable N and P management options available. Key words: Linum usitatissimum L., fertilizer placement, fertilizer form, nutrient uptake, seed yield, seed quality, oil quantity, urease inhibitor, Agrotain™

PHOSPHORUS PLACEMENT ON ACID ARENOSOLS OF THE WEST AFRICAN SAHEL

Phosphorus (P) deficiency is a major constraint to pearl millet (Pennisetum glaucum L.) growth on acid sandy soils of the West African Sahel. To develop cost-effective fertilization strategies for cash poor farmers, experiments with pearl millet were conducted in southwestern Niger. Treatments comprised single superphosphate hill-placed at rates of 1, 3, 5 or 7 kg P ha−1 factorially combined with broadcast P at a rate of 13 kg ha−1. Nitrogen was applied as calcium ammonium nitrate at rates of 30 and 45 kg ha−1. At low soil moisture, placement of single superphosphate in immediate proximity to the seed reduced seedling emergence. Despite these negative effects on germination, P placement resulted in much faster growth of millet seedlings than did broadcast P. With P application, potassium nutrition of millet was improved and seedling nitrogen uptake increased two- to three-fold, indicating that nitrogen was not limiting early millet growth. Averaged over the 1995 and 1996 cropping seasons, placed applications of 3, 5 and 7 kg P ha−1 led to 72%, 81% and 88% respectively, of the grain yield produced by broadcasting 13 kg P ha−1. Nitrogen application did not show major effects on grain yield unless P requirements were met. A simple economic analysis revealed that the profitability of P application, defined as additional income per unit of fertilizer, was highest for P placement at 3 and 5 kg ha−1.