Relationships between Leaf‐Blade Nitrogen and Relative Seedcotton Yields

Abstract

ceed plant needs or when fertilizer applications are not synchronized with plant uptake. Today, methods for Nitrogen fertilization is a required production practice for cotton predicting N status of cotton grown in the Midsouth are (Gossypium hirsutum L.) with risks arising from under-and overeither inaccurate or require additional studies before fertilization. Tissue testing for diagnosing N deficiencies in crops can use leaf blades and the total N concentration, but this practice has the critical values used in tissue testing can be accepted not been rigorously examined in cotton. The primary objective of and used by farmers and extension personnel (Bock and these experiments was to determine the leaf-N concentration of the Adams, 1980;Sabbe and Zelinski, 1990). Critical values uppermost, fully mature leaf blade below which yield loss could be are used in tissue testing to separate N-deficient from expected. Nitrogen-rate field experiments were conducted at 12 re-N-sufficient plants. Plants with tissue samples that consearch station and farm sites in the Midsouth USA in Louisiana, tain N levels above the critical value are considered Arkansas, Mississippi, and Alabama in 1996 and 1997. Leaf-blade sufficient in N and no N fertilizer would likely be needed total N concentrations associated with yield loss were 4.3% N at early while those plants with N concentrations below the critibloom (R 2 ϭ 0.50) and 4.1% N at mid-bloom (3 wk after early bloom, cal value are considered deficient in N and N applica-R 2 ϭ 0.32). The likelihood of applying N when not needed could be tions might be advisable. Inaccurate critical values can reduced by lowering the early bloom critical value to 3.9%. Only 4% result in the over-application or under-application of N. of all samples sufficient in N would have been incorrectly diagnosed N deficient at that critical value, but 44% of all deficient samples The principal method for assessing cotton-N status would have been misidentified as N sufficient. Reduced yields due under irrigated conditions is the petiole nitrate test. The to over application of N were evident in some samples with leaf N test is a snapshot of N movement to leaves because it between 4.6 and 4.8% at early bloom. These concentrations were also is an analysis of a transportable form of N, and because common for N-sufficient plants, making accurate diagnoses of the petioles or leaf stems are the conduit for nitrate transover application of N unlikely. Our leaf-N critical values probably port from roots. Petiole nitrate is a sensitive measure of differ from previously established values because earlier values were N movement to leaves, but it is probably hypersensitive derived via survey techniques and because faster fruiting cultivars because of soil moisture effects on petiole nitrate. Remay require higher leaf N.searchers have found petiole nitrate testing a better measure of soil moisture status than cotton-N status (Bock and Adams, 1980; Touchton et al., 1981). Another

Nitrogen Contribution of Peanut Residue to Cotton in a Conservation Tillage System

“…The linear and quadratic increase of leaf N concentration as N rate increased (Table 3) is consistent with the plant partitioning N to the younger leaves (upper main stem leaves) and reproductive parts when N is not limited (Tewolde et al, 2005). As dry matter accumulation increased (1st square to mid-bloom), N is partitioned to reproductive structures, which would decrease leaf N concentrations in the younger leaves (Bell et al, 2003;Tewolde et al, 2005). However, the reported critical leaf N concentration measured at mid-bloom for the Southeast Cotton Belt is 41 g kg −1 (Bell et al, 2003).…”

“…As dry matter accumulation increased (1st square to mid-bloom), N is partitioned to reproductive structures, which would decrease leaf N concentrations in the younger leaves (Bell et al, 2003;Tewolde et al, 2005). However, the reported critical leaf N concentration measured at mid-bloom for the Southeast Cotton Belt is 41 g kg −1 (Bell et al, 2003). No leaf N concentrations measured at mid-bloom were above this reported critical level for any growing season.…”

Nitrogen and Potassium in Narrow-Row Cotton

“…Authors emphasized that increasing plant height for narrow-row-space cotton is not desirable because it interferes with harvest. Furthermore, high N rates lead the plants into continuous growth, lengthening the cycle and reducing yield (Bell et al, 2003). Other studies found similar results of N rates leading to taller plants (Bogiani et al, 2011;Gottardo, 2012;Galhardo et al, 2013).…”

“…Higher rates of N may be required in narrow row spacing due to higher populations compared to conventional systems. Nevertheless, excessive use of N can reduce yield because plants will grow taller and take longer to mature (Bell et al, 2003), which is not desired in narrow-row systems. Hence, N rates must be appropriate for avoiding excessive growth in a long cycle.…”

In-Season Side-Dressing of Urea and Ammonium Nitrate to Cotton on No-Till Soils with High Residual Nitrogen and Pre-Plant Nitrogen Application

“…The sensitivity of cotton leaf N to N application is greater at early bloom than at any other growth and developmental stages [12] [13]. This trend indicates monitoring of leaf N nutrition status at early bloom is especially helpful in deciding whether supplemental N application is required.…”